CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 62/1 10,205 filed January 30, 2015, and U.S. Provisional Patent Application No. 62/189,325 filed July 7, 2015, each of which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

[0002] The invention is for use in the field of oil and gas drilling operations and provides a device for use in recovering used drilling fluids from drill cuttings.

BACKGROUND OF THE INVENTION

[0003] The loss of drilling fluids presents several technological and cost challenges to the energy exploration industry. These challenges generally include the seepage losses of drilling fluids to the formation, the recovery of drilling fluids at surface and/or the disposal of drilling detritus or cuttings that are contaminated with drilling fluid. In the context of this description, "drilling fluid" is both fluid prepared at surface used in an unaltered state for drilling as well as all fluids recovered from a well that may include various contaminants from the well including water and hydrocarbons (both liquid and gas).

[0004] During the excavation or drilling process, drilling fluid losses can reach levels approaching 300 cubic meters of lost drilling fluid over the course of a drilling program. With some drilling fluids having values in excess of $1600 per cubic meter, the loss of such volumes of fluids represents a substantial cost to drill operators.

[0005] Drilling fluids are generally characterized as either "water-based" or "oil-based" drilling fluids that may include many expensive and specialized chemicals as known to those skilled in the art. As a result, it is desirable that minimal quantities of drilling fluids are lost during a drilling program such that many technologies have been considered and/or employed to minimize drilling fluid losses both downhole and at surface.

[0006] Additionally, in some areas the delivery of oil or water for the formulation of drilling fluids can present several costly challenges for some operations; specifically desert, offshore and even some districts where communities will not allow allocation of water for this use.

[0007] As noted above, one particular problem is the separation of drilling fluid and any hydrocarbons from the formation that may be adhered to the drill cuttings (collectively "fluids") at the surface. The effective separation of various fluids from drill cuttings has been achieved by various technologies including but not limited to; hydrocyclones, mud cleaners, linear motion shakers, scroll centrifuges, vertical basket centrifuges (VBC), vacuum devices, and vortex separators. As known to those skilled in the art, these devices are typically rented by operators at costs ranging from $1000 to $2000 per day and, as a result, can also represent a significant cost to operators. Thus, the recovery of fluids necessary to recover these costs generally requires that the recovered fluid value is greater than the equipment rental cost in order for the recovery technology to be economically justified. On excavation projects where large amounts of high-cost drilling fluid are being lost (for example in excess of 3 cubic meters per day), daily rental charges for specialized separation equipment can provide favorable economics. In addition, an operator will likely also factor in the environmental effects and/or costs of disposal of drilling fluid contaminated drill cuttings in designing their drilling fluids/drill cutting separation/recovery systems.

[0008] Past techniques for separating drilling fluid from drill cuttings have also used liquid spraying systems to deliver "washing" liquids to drill cuttings as they are processed over shaker equipment. Such washing liquids and associated fluid supply systems are used to deliver various washing fluids as the cuttings are processed over a shaker and can include a wide variety of designs to deliver different washing fluids depending on the type of drilling fluid being processed. For example, washing liquids may be comprised of oil, water, or glycol depending on the drilling fluid and drill cuttings being processed over the shaker. Generally, these washing fluids are applied to reduce the viscosity and/or surface tension of the fluids adhered to the cuttings and allow for more fluids to be recovered. However, these techniques have generally not been cost effective for many drilling fluids as the use of diluting fluids often produces unacceptable increases in drilling fluid volume and/or changes in chemical consistency and rheological properties of the drilling fluid.

[0009] Thus, while various separation systems are often effective and/or efficient in achieving a certain level of fluids/cuttings separations, each form of separation technology can generally only be efficiently operated within a certain range of conditions or parameters and at particular price points. For example, standard shakers utilizing screens are relatively efficient and consistent in removing a certain amount of drilling fluid from cuttings where, during the typical operation of a shaker, an operator will generally be able to effect drilling fluid/cuttings separation to a level of about 12-40% by weight of fluids relative to the drill cuttings (i.e. 12-40% of the total mass of recovered cuttings is drilling fluid). The range of fluids/cuttings wt % is generally controlled by screen size wherein an operator can effect a higher degree of fluids/cuttings separation by using a larger screen opening (such as 50-75 mesh) and a lower degree of fluids/cuttings separation with a smaller screen opening (such as up to 325 mesh). The trade-off between using a large mesh screen vs. a small mesh screen is the effect of mesh screen size on the quantity of solids passing through the screen and the time required to effect that separation. That is, while an operator may be able to lower the fluids retained on cuttings coming off the shaker with a larger mesh screen (50-75 mesh), the problem with a larger mesh screen is that substantially greater quantities of solids will pass through the screen, that then significantly affect the rheology and density of the recovered fluids and/or require the use of an additional and potentially less efficient separation technology to remove those solids from the recovered drilling fluids. Conversely, using a small mesh screen, while potentially minimizing the need for further downstream separation techniques to remove solids from recovered drilling fluids, results in substantially larger volumes of drilling fluids not being recovered, as they are more likely to pass over the screens hence leading to increased drilling fluids losses and/or require subsequent processing.

[0010] Accordingly, in many operations, an operator will condition fluid recovered from a shaker to additional processing with a centrifugal force type device in order to reduce the fluid density and remove as much of the fine solids as possible before re-cycling or reclaiming the drilling fluid. However, such conditioning requires more expensive equipment such as centrifuges, scrolling centrifuges, and hydrocyclones which then contribute to the overall cost of recovery. These processing techniques are also directly affected by the quality of the fluid they are processing, so fluids pre-processed by shakers using a coarse screen will not be as optimized as those received from finer screens.

[0011 ] Furthermore, the performance of centrifuges, hydrocyclones and other equipment are directly affected by the viscosity and density of the feed fluid. As a result, drilling fluid recovery techniques that send heavy, solids-laden fluids to secondary processing equipment require more aggressive techniques such as increased g-forces and/or vacuum to effect separation which will typically cause degradation in the drill cuttings.

[0012] Further still, such secondary processing equipment typically cannot process drill cuttings and drilling fluids at the same throughput values of a shaker with the result being that additional separation equipment may be required or storage tanks may be required to temporarily hold accumulated drilling fluid.

[0013] Thus, the operator will try to balance the cost of drilling fluid losses with the quality of the fluid that is recovered together with other considerations. While operators will typically have little choice in the quality of the cuttings processing and fluid recovery techniques available, many operators will operate separation equipment to provide recovered drilling fluid density about 200-300 kg/m ³ heavier than the density of the circulating fluid in the system. This heavier fluid which would contain significant quantities of fine solids and that, when left in the drilling fluid, will either immediately or over time impair the performance of the drilling fluid or any other type of fluid.

[0014] As a result, there continues to be a need for systems that economically increase the volume of fluids recovered from a shaker without negatively impacting the rheological properties of the recovered drilling fluid. [0015] In addition, there has been a need to develop low-cost retrofit technologies that can enhance fluid recovery and do so at a fractional cost level to mechanisms and technologies currently employed. Further, there has been a need for retro-fit technologies that can be utilized on a variety of shakers from different manufactures and that can be used to enhance the operation of existing shakers.

[0016] The use of vacuum technology has been one solution to improving the separation of drilling fluids. However, vacuum technologies may also present dust and mist problems in the workplace. With past vacuum techniques there is a need to regularly clean clogged screens with high pressure washes. High pressure washing of screens creates airborne dust and mist hazards to operators. Thus, there continues to be a need for technologies that minimize the requirement for screen washing.

[0017] Further still, there has been a need for improved fluid separation systems on the underside of a vacuum screen that allows relatively large volumes of air to be drawn through a vacuum screen to be effectively and efficiently separated from the relatively low volume of drilling fluid being drawn through a vacuum screen. That is, there has been a need for improved fluid/air separation systems.

[0018] Further still, there has been a need for retrofit systems that can be adapted to standard shakers without substantial modification to the existing shaking and that allow for quick and easy installation at a job site. In addition, there has been a need for retrofit systems that also allow for ready disassembly of the system for transport and/or maintenance.

[0019] As a result, there has also been a need for systems that improve the ability of shaker systems to improve fluid separation at a shaker. Currently used systems typically include a vacuum conduit running from the shaker screen connection to a large recovery tank which is in line with a powerful vacuum system. According to normal operations, the vacuum systems run continuously until the large tanks become filled with recovered drilling fluid, at which point the recovered drilling fluid is pumped out of the recovery tank and conveyed to the main drilling fluid supply vessels which are known as "mud tanks." Improved systems which reduce the complexity of fluid transfer and related energy requirements are desirable. [0020] Various technologies including vacuum technologies have been used in the past for separating drilling fluids from drill cuttings including vibratory shakers.

[0021 ] For example, U.S. Pat. No. 4,350,591 describes a drilling mud cleaning apparatus having an inclined travelling belt screen and degassing apparatus including a hood and blower. U.S. Patent Publication No. 2008/0078700 discloses a self-cleaning vibratory shaker having retro-fit spray nozzles for cleaning the screens. Canadian Patent Application No. 2,664,173 describes a shaker with a pressure differential system that applies a non-continuous pressure across the screen. U.S. Patent 4,639,258 and U.S. Patent Publication Nos. 2014/01 10357, 2014/0091028 and 2013/0074360 describe vacuum-assisted shale shakers. U.S. Patent 8,691 ,097 describes a separating tower with a top vacuum discharge port and a bottom solids discharge port. Other references including U.S. Pat. No. 6,092,390, U.S. Pat. No. 6,170,580, U.S. Patent Publication No. 2006/01 13220 and PCT Publication No. 2005/054623 describe various other separation technologies. Each of the above-noted references is incorporated herein by reference in entirety.

[0022] Vacuum technologies based on shakers are described in U.S. Patent Publication Nos. 2014/0091028, 2013/0092637, 2013/0074360, 2012/0279932 and 201 1/0284481 , each of which is incorporated herein by reference in entirety.

[0023] Thus, while past technologies may be effective to a certain degree in enabling drilling fluid/cuttings separation, it remains desirable to improve aspects of the design and operation of alternative separation devices that enable expedient conveyance of the collected drilling fluid in a convenient and cost-effective manner with minimal equipment requirements.

SUMMARY OF THE INVENTION

[0024] One aspect of the present invention is a screened vacuum enclosure for use in separating drilling fluid from drill cuttings in a vacuum-based shaker system, the screened vacuum enclosure comprising: a. a rectangular frame including downstream and upstream longitudinal outer frame members and transverse outer frame members, with one or more vacuum ports extending through or into one of the longitudinal outer frame members, the vacuum ports communicating vacuum suction to the interior of the screened vacuum enclosure; b. one or more inner frame support members connected to the outer frame members; c. a screen attached to the top surface of the frame; and d. a floor attached to at least part of the bottom surface of the frame.

[0025] In some embodiments, the vacuum ports extend through the outside front surface of the downstream longitudinal frame member to the interior of the frame.

[0026] In some embodiments, the one or more inner frame support members include longitudinal and transverse inner frame members dividing the inside of the rectangular frame into a plurality of interior sections and wherein vacuum pipes are placed in at least some of the vacuum ports, the vacuum pipes having open ends located in at least some of the interior sections.

[0027] In some embodiments, the inner frame support members comprise two longitudinal inner frame members and two transverse inner frame members dividing the interior of the rectangular frame into a grid with nine interior sections, and defining three interior longitudinal areas and three interior transverse areas.

[0028] In some embodiments, the screened vacuum enclosure includes nine substantially equi-spaced vacuum ports.

[0029] In some embodiments, the vacuum ports are round and have interior threaded sidewalls for installation of one or more threaded plugs.

[0030] In some embodiments, the screened vacuum enclosure includes nine vacuum pipes with one vacuum pipe placed in each one of the nine vacuum ports.

[0031] In some embodiments, one pipe of the nine vacuum pipes terminates in each one of the nine interior sections. [0032] In some embodiments, each of the three transverse areas includes three vacuum pipes of the nine vacuum pipes with one of the three vacuum pipes terminating in each of the three interior sections included in each of the three transverse areas.

[0033] In some embodiments, the screened vacuum enclosure includes four vacuum pipes installed in the second, fourth, sixth and eighth vacuum ports of the nine vacuum ports and wherein the plugs are installed in the first, third, fifth, seventh and ninth vacuum ports of the nine vacuum ports.

[0034] In some embodiments, each one of the four vacuum pipes extends across the three longitudinal areas and terminates in the longitudinal area adjacent the longitudinal outer frame member opposing the longitudinal outer frame member with the vacuum ports.

[0035] In some embodiments, each of the two inner longitudinal frame members includes three equi-spaced channels adjacent the floor to allow vacuum suction to extend to longitudinal sections that do not include the open ends of the vacuum pipes.

[0036] In some embodiments, at least some of the outer frame members are at least partially hollow and are joined to form a continuous hollow space within the rectangular frame, and wherein the vacuum ports join the hollow space and communicate vacuum suction to the interior of the screened vacuum enclosure via one or more additional openings in the rectangular frame.

[0037] In some embodiments, the additional openings are provided by one or more slots located in one or more of the longitudinal or transverse outer frame members.

[0038] In some embodiments, the one or more slots is eight slots substantially equi- spaced across the length of the interior side of the upstream longitudinal outer frame member, and wherein the downstream outer frame member includes six substantially equi-spaced vacuum ports.

[0039] In some embodiments, the eight slots have substantially identical lengths and different widths, with widest slots located at the center of the upstream longitudinal member, and with narrowest slots located adjacent to the ends of the upstream longitudinal member.

[0040] In some embodiments, the slots each have radiused corners.

[0041 ] In some embodiments, the slots have a total open area greater than the total open area of the plurality of vacuum ports.

[0042] In some embodiments, the outer frame has mitered corners and each end of the downstream longitudinal frame member has a vacuum port extending into a corresponding mitered corner of the mitered corners.

[0043] In some embodiments, the one or more inner frame support members is seven transverse inner frame support members.

[0044] In some embodiments, the screened vacuum enclosure further comprises seven spacer elements located between corresponding transverse inner frame support members and the floor, the spacer elements having a length less than the length of the transverse inner frame support members, thereby providing upstream and downstream spaces between the transverse inner frame support members and the floor.

[0045] In some embodiments, the floor covers between about one quarter to about three quarters of the interior area of the rectangular frame and is bounded by the entire length of the downstream longitudinal member, the entire length of an opposing inner longitudinal support member and opposing portions of the transverse outer frame members.

[0046] In some embodiments, the floor covers about half of the interior area.

[0047] In some embodiments, the one or more slots is provided by a pair of opposing slots located in the portions of the transverse outer frame members, and wherein the transverse outer frame members each have an interior boundary limiting the interior hollow space.

[0048] In some embodiments, the interior boundary in each transverse outer frame member is located adjacent to the upstream end of each of the opposing slots. [0049] In some embodiments, the floor has two sloped portions increasing in height from the opposing portions of the transverse outer frame members to a substantially central apex.

[0050] In some embodiments, the floor is supported by a central reinforcing member attached to the underside of the floor and the upstream interior area of the rectangular frame not covered by the floor includes one or more transverse inner frame members.

[0051 ] In some embodiments, the one or more vacuum ports is provided by a single vacuum port located in an adapter inserted in a slot in the downstream outer frame member which is open to the interior of the frame.

[0052] In some embodiments, the adapter includes (i) an elongated base with a plug portion configured to fit into the slot and (ii) an outward extending funnel-shaped portion terminating with the vacuum port.

[0053] In some embodiments, the elongated base is defined by having one or more bolt or screw holes for connection of the adapter to the downstream outer frame member.

[0054] In some embodiments, the floor covers between about one quarter to about three quarters of the interior area of the rectangular frame and is bounded by the entire length of the downstream longitudinal member, the entire length of an opposing inner longitudinal support member and opposing portions of the transverse outer frame members.

[0055] In some embodiments, the floor covers about half of the interior area.

[0056] In some embodiments, the floor has three sloped sections with first and second triangular sections sloping downward from downstream corners of the rectangular frame and a central trapezoidal section sloping downward from the inner longitudinal support member to the downstream longitudinal frame member.

[0057] In some embodiments, the downstream longitudinal outer frame member includes a vacuum pressure gauge for displaying vacuum pressure in the hollow space. [0058] Another aspect of the invention is a vacuum shaker system for separation of drilling fluid from drill cuttings, the system comprising: a. a shaker having a plurality of screen beds including a downstream screen bed and one or more upstream screen beds; b. a downstream screened vacuum enclosure as described herein placed on the downstream screen bed; c. a vacuum distributor connected to at least some of the vacuum ports of the downstream screened vacuum enclosure; and d. a vacuum source connected to the vacuum distributor.

[0059] In some embodiments, the system further comprises at least one additional upstream screened vacuum enclosure as recited herein which is substantially identical to the downstream screened vacuum enclosure with the proviso that, in the upstream screened vacuum enclosure, all vacuum pipes or adapters are removed and all vacuum ports are sealed to restrict the function of the upstream screened vacuum enclosure to that of a screen frame only, thereby providing a means to shake drill cuttings at a similar level from the upstream screened vacuum enclosure to the downstream screened vacuum enclosure.

[0060] In some embodiments, each one of the upstream screen beds of the shaker holds a separate upstream screened vacuum enclosure having features as defined for the upstream screened vacuum enclosure described herein.

[0061] In some embodiments, the system further comprises a wash module connected to two or more of the vacuum ports for pumping of wash fluid into the screened vacuum enclosure to expel obstructions from the hollow space of the screened vacuum enclosure.

[0062] Another aspect of the invention is a kit for assembly of a screened vacuum enclosure for use in separating drilling fluid from drill cuttings on a shaker, the kit comprising: a. outer frame members including two longitudinal outer frame members and two transverse outer frame members, one of the longitudinal outer frame members defined by a series of vacuum ports and both of the transverse outer frame members defined by a plurality of notches; b. inner frame members including longitudinal inner frame members and transverse inner frame members, the ends of the longitudinal inner frame members configured to fit into the notches of the transverse outer frame members and the lengths of each of the longitudinal members defined by a first set of openings provided for passage and holding of the transverse members and further defined by a second set of openings provided for passage and holding of a plurality of vacuum pipes; and c. a covering floor structure dimensioned to cover one open side of the outer frame members.

[0063] In some embodiments, the kit further comprises a plurality of vacuum pipes dimensioned to enter the vacuum ports and fit through the second set of openings.

[0064] In some embodiments, the kit further comprises a second set of inner longitudinal frame members, each containing a set of regularly spaced channels, such that, when the screened vacuum enclosure is assembled and in use in conjunction with a vacuum source and a shaker, vacuum pressure is transmissible through all sections of a grid formed by the inner frame members.

[0065] In some embodiments, the kit further comprises a set of plugs for closure of selected vacuum ports among the series of vacuum ports.

[0066] In some embodiments, the interior sidewalls of the vacuum ports are threaded and the plugs are threaded for corresponding installation into the vacuum ports.

[0067] In some embodiments, the kit further comprises instructions for assembly of a screened vacuum enclosure with a commercially-obtained screen and either nine vacuum pipes or four vacuum pipes, wherein the assembly of the screened vacuum enclosure with nine vacuum pipes uses longitudinal inner frame members without channels and the screened vacuum enclosure with four vacuum pipes uses longitudinal inner frame members with channels.

[0068] In some embodiments, the kit further comprises an adhesive for fixing the covering floor structure to one side of the frame and for fixing a screen to the other side of the frame.

BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Various objects, features and advantages of the invention will be apparent from the following description of particular embodiments of the invention, as illustrated in the accompanying drawings. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of various embodiments of the invention. Similar reference numerals indicate similar components.

Figure 1 is a top perspective view of one embodiment of the screened vacuum enclosure 10 with nine vacuum pipes 28a - 28i installed in nine vacuum ports 26a - 26i.

Figure 2 is an exploded top perspective view of the same embodiment shown in Figure 1 .

Figure 3 is a bottom perspective view of the frame 12 and vacuum pipes 28a - 28i installed in nine vacuum ports 26a - 26i in same embodiment shown in Figures 1 and 2, with the floor component 30 removed.

Figure 4 is a top perspective view of a second embodiment of the screened enclosure 110 with four vacuum pipes 128b, 128d, 128f and 128h installed in four of the nine vacuum ports.

Figure 5 is an exploded top perspective view of the same embodiment shown in Figure 4.

Figure 6 is a bottom perspective view of the frame 112 and four vacuum pipes 128b, 128d, 128f and 128h in the same embodiment 110 shown in Figures 4 and 5, with the floor component 130 removed. Figure 7 is a perspective view of a third embodiment of the screened vacuum enclosure 210 with vacuum ports 226a-f in frame member 214a which extend into a continuous hollow space within the outer frame portion defined by frame members 214a-d.

Figure 8 is a perspective view of the embodiment 210 of Figure 7 with the screen removed and showing a series of slots 244a-d, 246a-b, and 248a-b in frame member 214b which join the hollow space of the outer frame. Also shown are transverse support members 218a-g and corresponding spacer elements 242a- g-

Figure 9A is a top view of upstream frame member 214b showing mitered ends 215a-b which are configured to join corresponding mitered ends of outer frame members 214c and 214d.

Figure 9B is a side elevation view of the inner side of upstream frame member 214b showing slots 244a-d, 246a-b, and 248a-b.

Figure 10A is a top view of downstream frame member 214a showing mitered ends 217a-b which are configured to join corresponding mitered ends of outer frame members 214c and 214d.

Figure 10B is a side elevation view of the outer side of downstream frame member 214a showing vacuum ports 226a-f.

Figure 11 A is a plan view of the screened vacuum enclosure embodiment 210 with the screen 232 partially cut away and showing transverse inner frame support members 218a-g.

Figure 11 B is a cross sectional view taken along line 1 1 B of Figure 1 1 A.

Figure 11 C is a magnified view of circle 1 1 C in Figure 1 1 B, showing detail of slots 244a-b, as well as transverse members 218a-b and corresponding spacer elements 242a-b. Mitered end 215a is also shown. Figure 12 is a perspective view of the screened vacuum enclosure embodiment 210 with the screen removed and showing hollow-body adapters 250b-e (for connection of vacuum lines) and plugs 252a and 252f connected thereto at the vacuum ports. The dashed lines indicate the general direction of vacuum air flow downward through the screen, through the spaces provided by spacer elements, into the slots, through the hollow body of the screened vacuum enclosure 210 and out of the screened vacuum enclosure 210 via the vacuum ports and adapters 250b-e.

Figure 13 is a perspective view of the screened vacuum enclosure embodiment 210 with the screen removed and showing hollow-body adapters 250a-f connected to the vacuum ports. The dot-dashed lines indicate the direction of movement of wash fluid into the hollow body of members 214b and 214c of the screened vacuum enclosure via adapters 250a and 250f for the purpose of removing obstructions within the hollow body of the screened vacuum enclosure 210.

Figure 14 is a top perspective view of a fourth embodiment of the screened vacuum enclosure 310 with vacuum ports 326a-d in frame member 314a which extend into a continuous hollow space within the outer frame portion defined by frame members 214a and at least about the front half of frame members 314c and 314d.

Figure 15 is an exploded perspective view of the same embodiment of Figure 14.

Figure 16 is a magnified view of the inset 16 ^' of Figure 15 showing the general direction of air flow (with dashed arrows) downward into the enclosure 310, through slot 349a, through frame members 314c and 314a and out of ports 326a and 326b.

Figure 17 is a bottom perspective view of the same embodiment of Figures 14- 16. Figure 18 is a top perspective view of the same embodiment of Figures 14-17 with the screen removed to illustrate the perspective of the floor 330 with respect to its framing members 314a, 314c, 316 and 314d.

Figure 19 is a top perspective view of a fourth embodiment of the screened vacuum enclosure 410 with a wide adapter 450 fitted to a front slot (not shown).

Figure 20 is an exploded perspective view of the same embodiment of Figure 19 showing some of the features of the adapter 460.

Figures 21 A and 21 B are perspective views of the adapter 460 of the embodiment of Figures 19 and 20.

Figure 21 C is a side elevation view of the back of the adapter 460 of the embodiment of Figures 19, 20, 21 A and 21 B.

Figure 22 is a top perspective view of the same embodiment of Figures 19-21 with the screen removed.

Figure 23A is a top plan view of a vacuum shaker system showing installation of screened vacuum enclosure 10 on a shaker 1 and having nine vacuum pipes connected to a vacuum distributor 40.

Figure 23B is a top plan view of a vacuum shaker system showing installation of screened vacuum enclosure 110 on a shaker 1 and having four vacuum pipes connected to a vacuum distributor 40.

Figure 24A is a top plan view of a vacuum shaker system showing installation of screened vacuum enclosure 210 on a shaker 1 and having four adapters 250b-e and two plugs 252a and 252f connected to the screened vacuum enclosure 210. The four adapters 250b-e are connected to a vacuum distributor 40.

Figure 24B is a top plan view of a vacuum shaker system showing installation of screened vacuum enclosure 210 on a shaker 1 and having six adapters 250a-f connected to the screened vacuum enclosure 210. Adapters 250a and 250f are connected to a wash fluid reservoir 54 and pump 56 via bifurcated wash line 58. This system is provides a means for flushing out blockages inside the hollow body of the screened vacuum enclosure 210. The remaining adapters are connected to the vacuum distributor 40.

Figure 24C is a top plan view of a vacuum shaker system showing installation of screened vacuum enclosure 210 on a shaker 1 and having six adapters 250a-f connected to the screened vacuum enclosure 210. Each of the six adapters 250a-f is connected to the vacuum distributor 40.

Figure 25 is a top plan view of a vacuum shaker system showing installation of screened vacuum enclosure 310 on a shaker 1 and having four adapters 350a-d connected to the screened vacuum enclosure 310. Each of the four adapters 350a-d is connected to the vacuum distributor 40.

Figure 26 is a top plan view of a vacuum shaker system showing installation of screened vacuum enclosure 410 on a shaker 1 and having a single adapter 460 connected to the screened vacuum enclosure 410 which is directly connected to the vacuum source.

DETAILED DESCRIPTION OF THE INVENTION

Rationale

[0070] Existing vacuum screen fluid recovery systems, such as the systems described in U.S. Patent Publication Nos. 2014/0091028, 2013/0092637, 2013/0074360, 2012/0279932 and 201 1/0284481 (each incorporated herein by reference in entirety), use a vacuum device attached to the underside of the frame of a screen on a shaker (see for example, Figure 1 E of U.S Patent Publication No. 2013/0074360, which is attached to about one third of the underside of the screen frame). This vacuum system operates by suction of the drilling fluid from the drill cuttings as they vibrate on a downstream shaker screen after having vibrated without vacuum suction across one or more upstream shaker screens. The recovered drilling fluid is then conveyed under vacuum pressure to a storage tank and then circulated to mud tanks for re-use.

[0071] While this system represents a valuable advancement in the art which has met with significant commercial success, improvements continue to be sought after in efforts to address certain disadvantages. For example, the existing vacuum attachment arrangement adds weight disproportionately to one portion of the downstream screen and interferes with the manufacturer's intended harmonics profile for the screen during the shaking process, thereby impacting the efficiency of separation. Commercially available shakers, screens and screen frames are not designed to handle such asymmetric stress. It would be advantageous to provide alternatives that address these issues as well as providing additional advantages. Such advantages are provided by various embodiments of the present invention.

Introduction and Overview

[0072] The present invention has been made to address a number of shortcomings of existing vacuum-based liquid recovery systems. One such example is the issue of the extra weight placed on the screen by an external vacuum attachment connected to the underside of the screen as noted above. Therefore, the present invention allows the external vacuum manifold attachment and screen system to be replaced with a structure formed from a rectangular frame to which is fixed a top screen and an opposing floor. The rectangular frame is configured for installation of a series of vacuum pipes or adapters which may adopt various configurations and which are provided for connection to a vacuum system. This inventive structure is herein designated the "screened vacuum enclosure."

[0073] One of the long sides of the frame (a longitudinal frame member) of the screened vacuum enclosure is provided with a series of vacuum ports for provision of vacuum suction extending from the screen surface, down into the interior of the structure and the outward via the vacuum ports to the vacuum source. Advantageously, all connections of the parts of the device are sealed to preserve vacuum flow of air down from the screen and outward to the vacuum source. As such, the entire interior of the structure which is bounded by the outer frame members, the top screen and the floor, or a portion thereof, can be subjected to vacuum suction in a manner similar to the vacuum suction provided by the vacuum manifold structure of the vacuum systems described in U.S. Patent Publication Nos. 2014/0091028, 2013/0092637, 2013/0074360, 2012/0279932 and 201 1/0284481 (each incorporated herein by reference in entirety). The screened vacuum enclosure is more compact and lighter than the state-of-the-art vacuum screen system currently in use. It is expected that significant mitigation of the mechanical stress-related problems caused by direct connection of large vacuum attachments to the underside of the screen will be confirmed.

[0074] In certain embodiments, the weight of the screened enclosure is substantially similar to as that of a framed screen unit itself, as supplied by manufacturers. Furthermore, replacement of the external vacuum attachment system with the screened vacuum enclosure is expected to provide more space near the downstream end of the shaker. Certain embodiments of the screened enclosure are customizable by adding or removing vacuum conduit pipes to and from the frame as described hereinbelow. Thus the system can be adapted to provide optimal vacuum pressure for removal of various types of drilling fluids from various consistencies of drill cuttings.

Definitions

[0075] As used herein, the term "screened vacuum enclosure" is a general term which encompasses all embodiments of the present invention which include a support frame with vacuum ports, a top screen and a bottom floor, as well as any pipes, adapters and/or plugs which may be connected to the vacuum ports.

[0076] As used herein, the term "frame" refers to a three dimensional support structure in the sense of a building frame rather than a two-dimensional surrounding support structure in the sense of a picture frame, and is used in context of describing a support structure for the screened vacuum enclosure.

[0077] As used herein, the terms "shaker" and the alternative art-accepted term "shale shaker" are synonymous and refer to an apparatus designed to support and vibrate screen frames in a process for recovering drilling fluid from drill cuttings. Used drilling fluid flows directly to the shale shakers for processing. Once processed by the shale shakers, the drilling fluid is deposited into containers known as "mud tanks."

[0078] As used herein, the terms "screen basket" and "screen bed" are synonymous and refer to a platform on the shaker which is responsible for transferring the shaking intensity of the machine to the screen frames as they are held securely in place. It is to be understood that all embodiments of the screened vacuum enclosure are dimensioned for placement on screen beds. Different shakers produced by different manufacturers may have screen beds with different dimensions, therefore requiring screen frames and/or screened vacuum enclosures with different dimensions.

[0079] As used herein, the term "drilling fluid" is synonymous with the term "mud" used in the art of drilling for hydrocarbons. Drilling fluids are integral to the drilling process and, in addition to providing other functions, serve to lubricate and cool the drill bit as well as convey the drilled cuttings away from the bore hole. These fluids are composed of a mixture of various chemicals in water or oil based solutions and can be very expensive. For both environmental reasons and to reduce the cost of drilling operations, drilling fluid losses are minimized by removing them from the drilled cuttings before the cuttings are disposed of.

[0080] As used herein, the term "drill cuttings" refers to any material conveyed upwards to the surface by the drilling process as a result of a drilling operation and may include soil, mud, and pieces/particles of various classes of rocks. When drill cuttings emerge from a drilling operation, they are typically covered with drilling fluid.

[0081 ] As used herein, the term "conduit" is used to describe any means for transmission of a vacuum pressure and/or liquids. Examples include, but are not limited to tubes, pipes or hoses of various compatible diameters which may be coupled to conveyance means driven by various types of liquid pumps or vacuum sources for conveyance of liquids.

[0082] As used herein, the terms "downstream" and "upstream" are relative terms used to identify locations in a process with respect to one or more other locations. A downstream location with respect to another location is a position closer to the end of the process than the other location. An upstream location with respect to another location is a position closer to the beginning of the process than the other location. These terms are in common usage in the arts relating to process engineering and are well understood by those skilled in the art.

[0083] As used herein, the terms "longitudinal" and "transverse" are used to distinguish between different frame members and specific interior areas of the screened vacuum enclosure. Longitudinal members and areas are greater in length than transverse members and areas.

[0084] As used herein, the term "screen" refers to any screen or mesh structure appropriate for separation of drilling fluid from drill cuttings on a shaker bed.

[0085] As used herein, the term "vacuum distributor" refers to an enclosed structure for distributing vacuum pressure or suction from a vacuum source to a plurality of vacuum lines extending to the screened vacuum enclosure of the present invention. The vacuum distributor may have any structure compatible with the function of splitting vacuum pressure to a plurality of vacuum lines extending to a screened vacuum enclosure.

[0086] Various aspects of the invention will now be described with reference to the figures. For the purposes of illustration, components depicted in the figures are not necessarily drawn to scale. Instead, emphasis is placed on highlighting the various contributions of the components to the functionality of various aspects of the invention. A number of possible alternative features are introduced during the course of this description. It is to be understood that, according to the knowledge and judgment of persons skilled in the art, such alternative features may be substituted in various combinations to arrive at different embodiments of the present invention. For example, the ensuing description illustrates embodiments that include screened vacuum enclosures configured for connection of the vacuum ports to various numbers of vacuum conduits in specific arrangements. Other arrangements with more than nine vacuum conduits as well as more or less than six or four vacuum conduits are possible and may be assembled by making routine modifications to the basic structure of the screened vacuum enclosure, or by simply connecting more or fewer vacuum conduits to alternative vacuum ports. Modifications required to arrive at such alternative embodiments can be effected by the skilled person without undue experimentation and are within the scope of the invention as defined by the claims.

[0087] Any terms which have not been explicitly defined herein, are to be considered as having meanings as they would be understood by persons skilled in the art. Such terms may also be reasonably inferable from the drawings and description and the combination thereof with the knowledge of the skilled person. Embodiment 1: Screened Vacuum Enclosure using Nine Vacuum Ports

[0088] With reference to Figures 1 to 3, there is shown a first embodiment of a screened vacuum enclosure 10. Figure 1 is a perspective view of the assembled structure and Figure 2 is an exploded view showing all major components of the structure. Figure 3 is a view from the bottom of the structure with the bottom floor cover removed, showing more detail relating to inner support members.

[0089] Referring now to Figures 1 and 2, it can be seen that the screened vacuum enclosure 10 includes a frame 12 formed of outer frame members 14a, 14b, 14c and 14d. The longitudinal outer frame members are opposing members 14a and 14b and the transverse outer frame members are opposing members 14c and 14d. The interior of the frame 12 has two interior longitudinal support members 16a and 16b as well as two interior transverse support members 18a and 18b. In this particular embodiment, outer longitudinal frame member 14a has a series of nine vacuum ports 26a to 26i. Vacuum pipes 28a to 28i extend from each one of the vacuum ports 26a to 26i. Alternative embodiments may include fewer or additional interior support members.

[0090] The structure of the screened vacuum enclosure 10 includes a top screen 32 which may be any type of screen known in the art and used for separating drill cuttings from drilling fluids. Such screens are well known to those skilled in the art. The screen is attached to the top surfaces of the frame 12 in certain embodiments may also be at least partially supported by the upper surfaces of the interior support members 16a, 16b, 18a and 18b. The screened vacuum enclosure 10 also includes a floor 30 attached to the bottom surfaces of the frame 12. An appropriate manner of attaching the screen 32 and floor 30 to the top and bottom surfaces of the frame 12 may be readily developed by one with ordinary skill in the art and may include the use of an adhesive such as an epoxy resin or cement, or other equivalent attachment means. Advantageously, the attachments provide a sealing arrangement such as a fitted gasket, for example, which prevents loss of vacuum pressure when the screened vacuum enclosure is in operation. Such attachment and sealing features are compatible with all embodiments of the invention and can be produced by the skilled person without undue experimentation.

[0091 ] More detail regarding the interior connections between the frame members 14a - 14d, the interior support members 16a, 16b, 18a and 18b and the vacuum pipes 28a - 28i will now be described with reference to Figure 3, which shows a perspective view from the bottom with the floor 30 removed. It is to be noted that this view would be obtained by a 180 degree rotation around the central transverse axis of the orientation of the frame 12 shown in the exploded view of the device shown in Figure 2.

[0092] As noted above, this particular embodiment of the screened frame enclosure 10 includes a rectangular frame structure 12 formed of four exterior frame members 14a, 14b, 14c and 14d in a rectangular shape. There are two longitudinal support members 16a and 16b and two transverse support members 18a and 18b. In this particular embodiment, the longitudinal support members 16a and 16b are wider than the transverse support members 18a and 18b and this enables assembly of the frame 12 to be facilitated by providing rectangular shaped lateral openings 20s, 20t in longitudinal support member 16b and rectangular shaped lateral openings 20u and 20v in longitudinal support member 16a. The rectangular transverse support members 18a and 18b are dimensioned to extend through and seal each of these rectangular lateral openings 20s, 20t, 20u and 20v to fix the transverse support members 18a and 18b in place within the frame 12. Likewise, rectangular notches 22w and 22x are provided in frame member 14d and rectangular notches 22y and 22z are provided in frame member 14c. The ends of longitudinal members 16a and 16b fit into these rectangular notches 22w, 22x, 22y, and 22z to fix the longitudinal members 16a and 16b to the frame 12.

[0093] In this particular embodiment, each of the longitudinal support members 16a and 16b is provided with a series of round openings for passage of vacuum conduit pipes. The skilled person will recognize that alternative embodiments will employ vacuum conduit pipes with square or rectangular cross sections and that the openings in longitudinal support members 16a and 16b will also be square or rectangular to allow passage of square vacuum pipes.

[0094] In the present embodiment, longitudinal support member 16b is provided with six round openings 24j, 24k, 24I, 24m, 24n and 24o. In a similar manner, longitudinal support member 16a is provided with three round openings 24p, 24q and 24r. Each of these nine openings 24j - 24r is aligned with a corresponding port from among the nine vacuum ports 26a - 26i in outer frame member 14a to allow passage of one of the vacuum pipes 28a - 28i. Therefore, vacuum pipe 28a is of intermediate length and extends through opening 24j in longitudinal member 16b, terminating in the middle section of the rightmost transverse interior area; vacuum pipe 28b is a short pipe which terminates before reaching longitudinal member 16b, terminating in the right section of the rightmost transverse interior area; and vacuum pipe 28c is a long pipe which extends through opening 24k in longitudinal member 16b as well as opening 24p in longitudinal member 16a, terminating in the left section of the rightmost transverse interior area.

[0095] The arrangement of pipes 28a to 28c with respect to the frame 12 and the inner support members 16a, 16b, 18a and 18b has just been described for the three rightmost inner rectangles of the grid in Figure 3. It can also be seen that the same pattern is used for the middle and leftmost inner rectangles. It can be seen that the longitudinal members 16a and 16b and transverse members 18a and 18b create a nine-section grid with nine inner rectangular sections. It is also helpful to consider the nine rectangle grid as also having three defined transverse areas (each containing three rectangles) and three defined longitudinal areas (each containing three rectangles). For greater clarity, the leftmost longitudinal area contains the inner ends of long pipes 28c, 28f and 28i; the middle longitudinal area contains the inner ends of intermediate pipes 28a, 28d and 28g; and the rightmost longitudinal area contains the inner ends of short pipes 28b, 28e and 28h. Likewise, the rightmost transverse area contains the inner ends of pipes 28a, 28b and 28c; the middle transverse area contains the inner ends of pipes 28d, 28e and 28f; and the leftmost transverse area contains the inner ends of pipes 28g, 28h and 28i.

[0096] The outer ends of the pipes 28a - 28i are each configured for attachment to a corresponding vacuum conduit line which extends to a central vacuum distribution unit (shown in Figures 7A and 7B). The open inner ends of the vacuum pipes 28a - 28i which are best seen in Figure 3, are angled with their open faces pointing toward the floor 30 (removed in Figure 3) of the screened vacuum enclosure 10. The present embodiment is configured to provide a vacuum pipe with an opening in each of the nine sections of the nine-section grid. The skilled person will recognize that the provision of a vacuum pipe opening in each section of the grid provides generally consistent vacuum coverage over substantially the entire area of the screen.

Embodiment 2: Screened Vacuum Enclosure using Four of Nine Available Vacuum Ports [0097] Turning now to Figures 4 to 6, there is shown an alternative embodiment of the screened vacuum enclosure 110, wherein efforts are made to use similar reference numerals and labels to indicate similar features. This particular embodiment may be considered a modification of the first embodiment, or vice versa. It can be seen that the general structure of the screened vacuum enclosure is similar to that of the embodiment of Figures 1 to 3. There is a frame 112 formed of outer frame members 114a, 114b, 114c and 114d and interior frame members 116a, 116b, 118a and 118b. Likewise, there is an attached floor 130 and screen 132 and longitudinal outer frame member 114a is defined by the presence of nine vacuum ports 126a - 126L Also similar to the first embodiment are the rectangular openings 120s, 120t, 120u and 120v in the longitudinal inner members 116a and 116b to accommodate the transverse members 118a and 118b and the notches 122w, 122x, 122y and 122z in the outer frame transverse members 14c and 14d to accommodate the ends of the longitudinal inner frame members 116a and 116b. However, in the present embodiment, only four of the nine vacuum ports (ports 126b, 126d, 126f and 126h) are fitted with vacuum pipes 128b, 128d, 128f and 128h. The remaining vacuum ports 128a, 128c, 128e, 128g and 128i are sealed with corresponding plugs 134a, 134c, 134e, 134g and 134i. Advantageously, in both of the main embodiments described, the interior of each of the round vacuum port openings is threaded to facilitate convenient insertion of correspondingly threaded plugs. It is to be understood that other arrangements of various numbers of pipes may be provided and these alternative embodiments may provide relative alterations in vacuum pressure across the screen 132. These alternative embodiments are within the scope of the invention.

[0098] It is seen in the bottom perspective view of Figure 6 (which is a view similar to that of Figure 3 of Embodiment 1 , and which is obtained by a 180 degree rotation at the central transverse axis of the orientation of the frame 112 shown in the exploded view of the device shown in Figure 5), that the longitudinal support members 116a and 116b are each provided with four pipe openings. Therefore, longitudinal support member 116b has openings 124j, 124k, 1241 and 124m and longitudinal support member 116a has openings 124n, 124o, 124p and 124q. The arrangement provided allows the four vacuum pipes 128b, 128d, 128f and 128h to extend across essentially the entire width of the frame such that their open inner ends are adjacent to the outer longitudinal frame member 114b which opposes outer longitudinal frame member 114a. In an alternative description, each one of the four pipe endings can be considered as residing in the leftmost longitudinal area. In addition, the end of pipe 128b can be considered as residing in the rightmost transverse area; the ends of pipes 128d and 128f reside in the middle transverse area and the end of pipe 128h resides in the leftmost transverse area.

[0099] The skilled person will recognize that the present arrangement of vacuum pipes 128b, 128d, 128f and 128h, which each terminate near frame member 114b would have the effect of providing the vacuum suction to only the leftmost rectangles of the grid (with reference to Figures 5 and 6). In certain cases, this may be desirable. However, the present embodiment is modified to allow vacuum suction to extend to all nine sections of the grid by provision of a series of channels in each of the longitudinal members 116a and 116b. Accordingly, longitudinal member 116b has channels 136a, 136b and 136c and longitudinal member 116a has channels 136d, 136e and 136f. As a result, for example, with reference to Figure 6, fluid may be pulled off the screen in the lower rightmost grid section by vacuum suction transmitted through channels 136c and 136f and into pipe 128h. The skilled person will recognize that a similar pathway of vacuum suction will occur in other parts of the grid, which is made possible by the presence of the other pairs of channels 136a/136d for pipe 128b and 136b/136e for pipes 128d and 128f. It is to be noted that while only one pair of channels 136a/136d is visible in Figure 5, all six channels are in fact present but obscured by the perspective position of the transverse members 118a and 118b in Figure 5.

[0100] The skilled person will recognize that the two different arrangements for providing suction via vacuum pipes according to the two embodiments described hereinabove, will provide different relative vacuum pressures at different locations of the screens. This differential vacuum suction may be characterized without undue experimentation and applied advantageously to separation of drilling fluids from drill cuttings with different characteristics in order to achieve an optimal balance between recovery of optimal volumes of drilling fluid with minimal generation of undesired fine particles of drill cuttings.

Embodiment 3: Screened Vacuum Enclosure with a Hollow Outer Frame Body and Six Vacuum/Wash Ports [0101 ] Turning now to Figures 7 to 13, there is shown an alternative embodiment of the screened vacuum enclosure 210, wherein efforts are made to use similar reference numerals and labels to indicate similar features relative to the first and second embodiments described hereinabove. This embodiment of the screened vacuum enclosure 210 includes a frame 212 formed of hollow outer frame members 214a, 214b, 214c and 214d and interior transverse support frame members 218a, 218b, 218c, 218d, 218e, 218f, and 218g which rest upon corresponding central spacer elements 242a, 242b, 242c, 242d, 242e, 242f and 242g. This embodiment also has a bottom floor 230 and a top screen 232 as similarly described for the previous embodiments.

[0102] As described in the previous embodiments, a series of vacuum ports 226a, 226b, 226c, 226d, 226e and 226f are provided in the forward facing (downstream) frame member 214a. However, these vacuum ports do not extend through the opposite side of frame member 214a but instead join the hollow interior space within frame member 214a. As noted above, all of the outer frame members 214a-d are hollow. These members are arranged such that their individual hollow spaces meet each other at the corners of the frame 212 to form a continuous hollow space that functions as a vacuum conduit when vacuum pressure is applied at one or more of the vacuum ports. While it is not necessary for the transverse support members 218a-g to be hollow and to join the hollow interior space of the frame, the skilled person will recognize that such an embodiment can be constructed if an analysis of air flow under vacuum pressure through the structure indicates that such a structure will enhance the removal of fluid from drill cuttings vibrating on the screen. Such an analysis and an interpretation thereof may be performed by the skilled person without undue experimentation.

[0103] The vacuum ports 226a-f are provided with a means for connecting adapters or plugs, such as interior threading. Adapters and plugs are then provided with corresponding outer threading and will be described in more detail hereinbelow.

[0104] Frame member 214b which opposes the front frame member 214a is provided with a series of slots on its side facing the interior of the screened vacuum enclosure 210. In this particular embodiment, there is one slot in each of the interior sections of the enclosure defined by the transverse support members 218a-g. Other embodiments may include fewer or additional slots. In this particular embodiment, slots 244a, 244b, 244c and 244d have similar dimensions, slots 246a and 246b have similar dimensions and are wider than slots 244a-d while having essentially the same length, and slots 248a and 248b have similar dimensions and are wider than slots 244a-d and 246a-b while having essentially the same length. These features are seen most clearly in Figure 9B. The functional characteristics of provision of slots with different sizes will be described in more detail hereinbelow.

[0105] Turning now to Figures 9A and 9B, there are shown top and side elevation views of frame member 214b, respectively. Both ends of frame member 214b are mitered to join the mitered ends of frame members 214c and 214d. Mitered ends of frame members 214c and 214d are not shown in Figures 9A and 9B, but can seen generally in Figures 8, 12 and 13. Figure 9B shows the series of slots 244a-d, 246a-b and 248a-b. The skilled person will recognize that if all slots were the same size, a lesser volume of air would be drawn into the slots closer to the center of the frame member 214a than at the slots closer to the ends of the frame member 214a. Therefore, the reason for providing wider slots toward the center of frame member 214b is to provide a more even distribution of air flow into frame member 214b which translates to a more even distribution of vacuum pressure against the underside of the screen and by association, a more effective separation of drilling fluid from the drill cuttings. All of the slots 244a-d, 246a-b and 248a-b are provided with radiused corners to enhance the structural integrity of frame member 214a.

[0106] Turning now to Figures 10A and 10B, there are shown top and side elevation views of frame member 214a, respectively. As described above for frame member 214b, both ends of frame member 214a are mitered to join mitered ends of frame members 214c and 214d (not shown in Figures 10A and 10B). The side elevation view of Figure 10B is of the outer side of frame member 214a showing the vacuum ports 226a-f. In this embodiment, all vacuum ports 226a-f are substantially identical circular openings. However, the skilled person will recognize that some variation is permissible. It is advantageous for the inner air flow characteristics however, that the total vacuum port area (the sum of the open areas of all vacuum ports 226a-f) be less than the total slot opening area (the sum of the open areas of all of the slots 244a-d, 246a-b and 248a-b) in order to have efficient air flow into and out of the screened vacuum enclosure 210. [0107] Figures 1 1 A is a top plan view of the screened vacuum enclosure 210 with the screen 232 partially cut away. Previously described features are shown. Figure 1 1 B is a cross sectional view taken along line 1 1 B of Figure 1 1 A. Because line 1 1 B is at the center, it is seen that the spacer elements lie directly beneath the transverse support members, as seen more clearly for spacer elements 242a and 242b in the magnified view of Figure 1 1 C. Although not shown, the skilled person will understand that if a similar cross sectional line were to be taken closer to frame member 214a or 214b, the spacer elements would not be visible because they do not extend the entire length of the transverse support members. At these sections, there are open spaces that permit airflow between the transverse sections defined by the transverse support members 218a-g as described in more detail below.

[0108] Turning now to Figure 12, there is shown a perspective view of the screened vacuum enclosure 210 with the screen removed and with hollow adapters 250b-e (for connection to a vacuum system) and plugs 252a and 252f connected to the vacuum ports 226a-f of the front frame member 214a. Dashed arrows indicate the general direction of airflow through the screened vacuum enclosure 210. While the ends of the arrows meet at right angles, the skilled person will recognize that this is a simplified representation made with the aim of preserving clarity. It is to be understood that under vacuum pressure applied at the adapters, air is drawn down from above the screen as indicated by the vertical arrows and then moves toward the slots in frame member 214b. Air moves through the spaces between the floor and the transverse frame members 218a-g. After entering the slots, the air flow moves within the continuous hollow space of the outer frame and out via the adapters 250b-e.

[0109] Shown in Figure 13 is a perspective view of the screened vacuum enclosure 210 which illustrates additional functionality provided by this embodiment. In this view, the plugs 252a and 252f have been replaced with adapters 250a and 250f which provide a means for direct pumping of a wash fluid into the hollow spaces of frame members 214d and 214c. It is seen that the leftmost vacuum port 226a is aligned with the leftmost mitered end 217a (as pictured in Figure 10A) and the rightmost vacuum port 226b is aligned with the rightmost mitered end 217b (as pictured in Figure 10A). This arrangement allows the pumped wash fluid to enter the hollow space of the transverse frame members 214d and 214c directly and continue to frame member 214b where obstructions in the hollow space are then expelled through the slots.

[0110] The skilled person will recognize that this action may be performed simultaneously with vacuum pressure provided on the adapters 250b-e (as shown in Figure 13A) or may be performed in an alternating fashion with washing first via adapters 250a and 250f, followed by vacuum suction at adapters 250b-e. The obstructive material would then ideally be broken up into smaller pieces by the force of pumping of the wash fluid and vacuumed out of the screened vacuum enclosure via the vacuum ports 226b-e.

[0111 ] The provision of a hollow space within the frame of this embodiment allows installation of a pressure gauge for measurement of vacuum pressure within the hollow space. Advantageously, the pressure gauge is installed in the downstream longitudinal member where it can be easily viewed by an operator at the front of the shaker.

Embodiment 4: Screened Vacuum Enclosure with a Partially Hollow Outer Frame Body and Four Vacuum Ports

[0112] Turning now to Figures 14 to 18, there is shown a fourth embodiment of the screened vacuum enclosure of the invention, wherein efforts are made to use similar reference numerals and labels to indicate similar features. The reference numerals are in the 300 series. This particular embodiment of the screened vacuum enclosure 310 is designed to exert vacuum pressure directly against only the downstream half of the surface area of the screen 332, although alternative embodiments may exert vacuum pressure directly against more or less than half of the surface area of the screen such as, for example, about two-thirds of the surface area, about three quarters of the surface area, about one-third of the surface area or about one quarter of the surface area of the screen 332, or any fraction of the surface area of the screen therebetween.

[0113] This particular embodiment of the screened vacuum enclosure 310 includes a frame 312 formed of exterior frame members 314a, 314b, 314c and 314d, interior transverse support frame members 318a, 318b, 318c and 318d and a single longitudinal inner support member 316 which forms the dividing line between the vacuum portion and the non-vacuum portion as described in more detail below. [0114] Frame member 314a has vacuum ports 326a, 326b, 326c and 326d and as such is oriented at the front of the shaker during operation. As for previous embodiments, the vacuum ports 326a, 326b, 326c and 326d are configured for installation of corresponding hollow-body adapters 350a, 350b, 350c and 350d to facilitate connection of vacuum lines. In some embodiments, the vacuum ports 326a-d have sidewalls with threading to facilitate threading installation of the adapters 350a-d.

[0115] This embodiment also has a bottom floor 330 and a top screen 332 as similarly described for the previous embodiments. While the top screen 332 is generally similar to the top screens of the other embodiments, the floor 330 covers only about half of the interior area of the screened vacuum enclosure 310, with boundaries formed by the front halves of the transverse frame members 314c and 314d, the longitudinal support member 316 and the front longitudinal support member 314a. In addition, the floor 330 is generally sloped upwards from each transverse side toward a mid-point apex 331. As such the floor 330 has two sloped portions 330a and 330b which meet at the apex 331 .

[0116] The purpose of structuring the floor 330 with the apex 331 is to reduce the total volume of space inside the screened vacuum enclosure below the screen 332 to make the vacuum pressure more effective and also to provide some gravity drainage of fluid collected in the screened vacuum enclosure 310. Figure 17 shows a perspective view of the underside of the screened vacuum enclosure 310 for the purpose of illustrating an H- shaped reinforcing member 333 generally centered on and supporting the two sloped portions 330a and 330b of the floor 330. Figure 18 shows a different perspective to indicate the sloped portions 330a and 330b of the floor 330. It can be seen in this perspective view that one side of the apex 331 of the floor 330 is joined close to the upper surface of the internal longitudinal support member 316 and the other side of the apex 331 of the floor 330 is joined close to the upper surface of the front frame member 314a. The two opposing transverse sides of the floor 330 are joined to frame members 314c and 314d near the bottom edges of these members and below the slots 349a and 349b.

[0117] The remaining half of the interior area of the frame 312 (the back half as shown in Figure 18) has no floor and therefore drilling fluid passing through the screen 332 above this area drops into the fluid recovery area beneath the screen beds before the drill cuttings pass onto the portion of the screen 332 above the floor 330 where they are subjected to vacuum pressure.

[0118] As noted above and described in the previous embodiments, the vacuum ports 326a, 326b, 326c and 326d are provided in the forward facing exterior frame member 314a. However, as described above for embodiment 3, these vacuum ports do not extend through the opposite side of frame member 314a but instead join a hollow interior space within frame member 314a. In addition, frame members 314c and 314d are each provided with a single corresponding slot 349a and 349b opening into the floor area and the frame members 314c and 314d are continuously hollow at least as far as the back end of the slots 349a and 349b (slot 349a is visible in Figures 14-16 and slot 348b is seen only in the perspective view of Figure 18). In this embodiment, all vacuum ports 326a-d are substantially identical circular openings. However, the skilled person will recognize that some variation in the shape of the ports is permissible.

[0119] The hollow portions of members 314c and 314d each join the hollow interior of member 314a for the purpose of providing a continuous hollow vacuum conduit extending from the vacuum ports 326a, 326b, 326c and 326d at least as far as the back of the slots 349a and 349b. In this particular embodiment, all exterior frame members 314a, 314b, 314c and 314d are hollow and interior walls are either installed within the hollow spaces of frame members 314c and 314d or formed integrally therewithin. In this particular example embodiment an interior wall 351a is shown inside the hollow space of member 314c is shown in the magnified perspective view of Figure 16 which represents box F16 of Figure 15. The purpose of this interior wall 351a (and a similar interior wall in member 314d (not shown)) is to form a rearward boundary for the interior hollow space. This decreases the total volume of the hollow interior space to make the vacuum pressure more effective. It is to be understood that providing vacuum throughout the entire exterior frame in this embodiment is not necessary because this embodiment requires provision of vacuum suction against only the front half of the screen 332. While this particular embodiment limits the front interior hollow space of the frame 312 by providing interior walls, other embodiments are possible where the rearward portions of frame members 314c and 314d are either of solid construction, or are hollow but filled with vacuum impervious filler material to provide boundaries in member 314c and 314d near or adjacent to the connection point of the interior longitudinal support member 316.

[0120] The general pattern of air flow under vacuum is now described with reference to Figure 16 (which represents box F16 of Figure 15) and Figure 18. The dashed arrows show the general direction of air flow in this area when the screened vacuum enclosure 310 is under vacuum. While the ends of the arrows meet at right angles, the skilled person will recognize that this is a simplified representation made with the aim of preserving clarity regarding the general direction of airflow. It is to be understood that during operation of the screened vacuum enclosure 310 under vacuum pressure applied at the vacuum ports 326a-d, air is drawn down from above the screen as indicated by the vertical arrows and then moves toward the slot 349a in frame member 314c and the slot 349b in frame member 314d (with the latter is seen only in Figure 18). After entering the slots 349a and 349b, the air flow moves within the continuous hollow space at the front of the outer frame 312 and out of the screened vacuum enclosure 310 via the vacuum ports 326a-d.

[0121] The skilled person will recognize that pumping of wash fluid into the front hollow portion of the frame 312 may be performed in a similar manner as described for embodiment 3, in order to dislodge obstructions. Such obstructions are dislodged through the slots 349a and 349b into the interior of the screened vacuum enclosure 310.

[0122] As for embodiment 3, the provision of a hollow space within the frame of this embodiment allows installation of a pressure gauge for measurement of vacuum pressure within the hollow space. Advantageously, in certain embodiments, the pressure gauge is installed in the downstream longitudinal member where it can be easily viewed by an operator at the front of the shaker.

[0123] As described for embodiment 3, the present embodiment may be configured for washing to remove obstructions by pumping of washing fluid into the device.

Embodiment 5: Screened Vacuum Enclosure with a Single Front Adapter and Vacuum Port [0124] Turning now to Figures 19 to 22, there is shown a fifth embodiment of the screened vacuum enclosure of the invention, wherein efforts are made to use similar reference numerals and labels to indicate similar features. The reference numerals are in the 400 series. This particular embodiment of the screened vacuum enclosure 410 is designed to provide vacuum suction directly against only the downstream half of the surface area of the screen 432, although, as described above for embodiment 4, alternative embodiments may provide vacuum suction directly against more or less than half of the surface area of the screen such as, for example, about two-thirds of the surface area, about three quarters of the surface area, about one-third of the surface area or about one quarter of the surface area of the screen, or any fraction of the surface area of the screen therebetween.

[0125] This particular embodiment of the screened vacuum enclosure 410 includes a frame 412 formed of exterior frame members 414a, 414b, 414c and 414d, interior transverse support frame members 418a, 418b, 418c and 418d and a single longitudinal support member 416 which forms the dividing line between the vacuum portion and the non-vacuum portion as described in more detail below.

[0126] Frame member 414a has a generally centered slot 447 for installation of an adapter 460 whose structure is shown in detail in three different views in Figures 21 A-C. The adapter 460 of this particular embodiment is of unitary construction and advantageously formed by injection molding according to known methods. Alternative embodiments of the adapter may be constructed of separate parts. The adapter 460 includes a base 464 with an integral plug portion 466 extending therefrom which is configured for press-fit installation in the slot 447 of the screened vacuum enclosure 410. The base 464 acts as a stop for the press-fit arrangement and provides a means for connection of the adapter 460 to the front frame member 414a. In the present embodiment, the connection is made with a pair of bolts 463a and 463b (see Figure 20) which fit in bolt holes 467a and 467b shown in greater detail in Figure 21 . Other means of connection of the adapter 460 to the front frame member 414a are possible, such as adhesives applied to the back side of the base 464 of the adapter. The front side of the adapter 464 transitions to a funnel portion 465 which terminates in a port 461. Advantageously, the interior sidewall of the port 461 is provided with threads to allow threading connection of a nozzle 462 to facilitate connection of a single vacuum line.

[0127] This embodiment also has a bottom floor 430 and a top screen 432 as similarly described for the previous embodiments. While the top screen 432 is generally similar to the top screens of the other embodiments, the floor 430 covers only about half of the interior area of the screened vacuum enclosure 410, as for embodiment 4, with boundaries formed by the front halves of the transverse frame members 414c and 414d, the longitudinal support member 416 and the front longitudinal support member 414a.

[0128] The three dimensional structure of the floor differs from the floor 330 of embodiment 4 by having three separately sloped portions 430a, 430b and 430c. Sloped floor portions 430a and 430b are triangular and diagonally sloped downwards from their respective front corners to promote flow of drilling fluid towards the center of the floor at portion 430b. As such, the highest point of floor portion 430a is at the front left corner of the screened vacuum enclosure 410 where the front longitudinal frame member 414a meets the left transverse frame member 413c. Likewise, the highest point of the of floor portion 430c is at the front right corner of the screened vacuum enclosure 410 where the front longitudinal frame member 414a meets the left transverse frame member 413d. As noted above, floor portion 430b, which is a trapezoidal shape, is also sloped. The slope of floor portion 430b is downward from a plane near the top edge of the inner longitudinal support member 416 to a plane near the bottom edge of the front longitudinal frame member 414a below the slot 447. The purpose of structuring the floor 430 with the sloped portions 430a-c is to reduce the total volume of space inside the screened vacuum enclosure below the screen 432 to make the vacuum pressure more effective and to promote gravity flow of fluid toward the slot.

[0129] The remaining half of the interior area of the frame 412 (the back half as shown in Figures 20 and 22) has no floor and therefore drilling fluid passing through the screen 432 above this area drops into the fluid recovery area beneath the screen beds before the drill cuttings pass onto the portion of the screen 432 above the floor 430 where they are subjected to vacuum pressure. [0130] One notable difference between embodiment 4 and the present embodiment is that it is not a requirement for any of the frame members 414a-d or portions thereof to be hollow, although they may be hollow if desired, provided that boundaries such as walls or vacuum impervious filler are provided on each side of the slot 447, to prevent vacuum from being pulled through the frame 412 (as this would decrease the efficiency of the system. As such, the vacuum suction is concentrated above the floor 430 of the screened vacuum enclosure 410.

[0131 ] The general pattern of air flow under vacuum is now described with reference to Figure 22. The dashed arrows show the general direction of air flow in this area when the screened vacuum enclosure 410 is under vacuum. While the ends of the arrows meet at right angles in most cases, the skilled person will recognize that this is a simplified representation made with the aim of preserving clarity regarding the general direction of airflow, as described above for the other embodiments. It is to be understood that during operation of the screened vacuum enclosure 410 under vacuum pressure applied at the nozzle 462, air is drawn down from above the screen as indicated by the vertical arrows and then moves toward the slot 447 in frame member 414a.

[0132] The skilled person will recognize that pumping of wash fluid into the screened vacuum enclosure 410 may be performed in a similar manner as described for embodiments 3 and 4, in order to dislodge obstructions within the funnel portion 465 of the adapter 460. Such obstructions are dislodged through the slot 447 into the interior of the screened vacuum enclosure 410.

[0133] One advantage of this embodiment relative to the other embodiments described hereinabove is that because there is only one vacuum port 461 , there is no need to provide a vacuum distributor when the screened vacuum enclosure 410 is incorporated into a vacuum-based shaker system (see Figure 26 which is described hereinbelow).

[0134] As for embodiments 3 and 4, the provision of a hollow space within the frame of this embodiment allows installation of a pressure gauge for measurement of vacuum pressure within the hollow space. Advantageously, in certain embodiments, the pressure gauge is installed in the downstream longitudinal member where it can be easily viewed by an operator at the front of the shaker. [0135] As described for embodiments 3 and 4, the present embodiment may be configured for washing to remove obstructions by pumping of washing fluid into the device.

Additional Features of Embodiments of Screened Vacuum Enclosures

[0136] Materials used for construction of the frame members of various embodiments of vacuum enclosures of the present invention may include wood, plastic or metal and may be determined without undue experimentation. Advantageously, the materials are lightweight to minimize addition of extra loads to the shaker. It is known in the art that binding agents can be used bind the screen mesh to the screen frame with maximal adhesion to both materials while being able to handle high heat, strong vibration, abrasive cuttings and corrosive drilling fluids. Plastic composite screens tend not to use adhesives but rather heat the mesh and melt it into the screen frame to form a bond. Such binding agents may be adapted to construct various embodiments of the screened vacuum enclosure without undue experimentation.

Vacuum Shaker Systems using Embodiments of the Screened Vacuum Enclosure

[0137] In accordance with another aspect of the invention, the screened vacuum enclosure is used as part of a vacuum-based shaker system for separation of drilling fluid from drill cuttings.

[0138] In Figures 23 to 26, there are shown various embodiments of vacuum-shaker systems using embodiments of the screened vacuum enclosure of the present invention in association with a similar shaker 1 of the type which has a series of four screen beds 3a, 3b, 3c and 3d. While screen frames are absent from the upstream screen beds 3b, 3c and 3d, it is to be understood that screen frames would be present during operation of the shaker 1 when drill cuttings are dropped onto the screen of the most upstream screen bed 3d and proceed downstream over the screens of screen beds 3c, 3b and finally, the various embodiments of the screened vacuum enclosure. For greater clarity, the screened vacuum enclosure is placed on the shaker 1 at the downstream end of the shaker and the connections to a vacuum distributor 40 (or directly to a vacuum source in the case of the system of Figure 26) are made at the downstream longitudinal member of the screened vacuum enclosure. [0139] In certain alternative embodiments, each one of the three upstream screen beds 3b, 3c and 3d has a screened vacuum enclosure placed thereon. These three screened vacuum enclosures are modified to function simply as screen frames by closure of each of the nine vacuum ports. More detail of this modification is provided hereinbelow.

[0140] Referring now to Figure 23A, it is seen that screen bed 3a holds a screened vacuum enclosure 10 which has vacuum pipes 26a - 26i extending from its downstream end. Each one of the vacuum pipes 26a - 26i is connected to a corresponding vacuum line 38a - 38i. For the sake of clarity, vacuum pipes 26b - 26h and vacuum lines 38b - 38h are not labelled but their positions are understood in context of the positions of vacuum pipes 26a and 26i and corresponding vacuum lines 38a and 38i. Each of the vacuum lines 38a - 38i is connected to a vacuum distributor 40 whose function is to disperse a centralized vacuum pressure provided by a vacuum pump or other source to each of the vacuum lines 38a - 38i. Advantageously, the vacuum distributor 40 is configured for variable connection and closure of vacuum connections to provide flexibility and compatibility with various embodiments of the screened vacuum enclosure of the present invention. Therefore, vacuum ports or connections (not shown) in the vacuum distributor 40 will be provided with closures or plugs so that the vacuum pressure in the distributor may be preserved in the event that a vacuum line is not connected thereto. Such closure elements are understood to be in use in the system embodiment shown in Figure 14B which is described below.

[0141] Referring now to Figure 23B, there is shown a shaker 1 as shown in Figure 23A and described above. The downstream screen bed 3a of the shaker 1 is provided with a screened vacuum enclosure 110 as described above with respect to Figures 4 to 6 (embodiment 2). It is seen that four vacuum pipes 128b, 128d, 128f and 128h extend from the downstream end of the screened vacuum enclosure 110. Each of these vacuum pipes 128b, 128d, 128f and 128h is connected to a corresponding vacuum line 138b, 138d, 138f and 138h (labels for 138d and 138f are omitted to preserve clarity but their positions are known from context). These vacuum lines 138b, 138d, 138f and 138h are connected to a vacuum distributor 40 which is configured for specific use with this embodiment of the screened vacuum enclosure 110, by closure of connectors or ports which are not intended to be used. The connectors or ports are provided with switches or valves for this function in certain embodiments, according to known arrangements which may be adapted for use with the vacuum distributor, without undue experimentation.

[0142] Turning now to Figure 24A, there is shown a system with a shaker 1 similar to the shown in Figure 23A and described above. The downstream screen bed 3a of the shaker 1 is provided with a screened vacuum enclosure 210 as described above with respect to Figures 7 to 13 (embodiment 3). Among the vacuum ports of the screened vacuum enclosure, ports 226a and 226f (not labelled in Figure 24A) are provided with plugs 252a and 252f. The remaining vacuum ports 226b-e (not labelled in Figure 24A) are connected to adapters 250b-e. Adapters 250b-e are connected to a vacuum distributor and the system will provide vacuum suction through the screened vacuum enclosure 210 in a manner similar to that shown in Figure 23A.

[0143] Figure 24B illustrates a system similar to that shown in Figure 15A, but with added functionality provided by connection of a washing module comprising a pump line 58 connected to adapters 250a and 250f which replace the plugs 252a and 252f of the system of Figure 15A. Pump line 58 includes a pump 56 for drawing wash fluid from a wash fluid reservoir 58. In operation, the pump draws fluid from the reservoir 54 and pumps it at a high rate into the hollow body frame of the screened vacuum enclosure 210 via pump line 54 and adapters 250a and 250f. Any obstructions within the hollow body frame will be dislodged and expelled from the hollow body frame via the slots in the back frame member 214b and ideally broken up into smaller pieces that can be subsequently vacuumed out. The skilled person will recognize that the washing step may be performed concurrently with the provision of vacuum pressure to the adapters 250b-f or the washing step may be performed alone and alternate with the provision of vacuum pressure to the adapters 250b-f .

[0144] Shown in Figure 24C is another system arrangement highlighting the versatility of the screened vacuum enclosure 210. In this system embodiment, adapters 250a and 250f are connected to vacuum ports 226a and 226f as shown in Figure 15B, but in this case, the adapters 250a and 250f are connected to the vacuum distributor 40 to provide a variation in vacuum-driven air flow through the hollow frame body of the screened vacuum enclosure 210. [0145] The skilled person will readily recognize that a number of variations in connections between the vacuum distributor 40 and the vacuum ports are possible. The vacuum ports 226a-f may be provided with inner threads which facilitate the process of making connections to adapters, plugs or even direct connection of threaded vacuum conduits which extend to a vacuum distributor or vacuum sources. In certain embodiments, each vacuum line extending to each vacuum port may be controlled individually to increase or decrease vacuum pressure provided to the hollow frame body of the screened vacuum enclosure 210. This will alter the air flow dynamics within the hollow body of the screened vacuum enclosure 210 to alter the vacuum-driven air flow on the screen to facilitate separation of drilling fluids of different consistencies from drill cuttings with different characteristics with the aim of achieving an optimal balance between recovery of optimal volumes of drilling fluid with minimal generation of undesired fine particles of drill cuttings.

[0146] Referring now to Figure 25, there is shown a shaker 1 as described for the other systems described hereinabove. The downstream screen bed 3a of the shaker 1 is provided with a screened vacuum enclosure 310 as described above with respect to Figures 14 to 18 (embodiment 4). It is seen that four adapters 350a, 350b, 350c and 350d extend from the downstream end of the screened vacuum enclosure 310. Each of these four adapters 350a, 350b, 350c and 350d is connected to a corresponding vacuum line. The vacuum lines are connected to a vacuum distributor 40 which is configured for specific use with this embodiment of the screened vacuum enclosure 310.

[0147] Referring now to Figure 26, there is shown a shaker 1 as described for the other systems described hereinabove. The downstream screen bed 3a of the shaker 1 is provided with a screened vacuum enclosure 410 as described above with respect to Figures 19 to 22 (embodiment 5). It is seen that a single adapter 460 extends from the downstream end of the screened vacuum enclosure 410 and is connected to a single vacuum line. The vacuum line is connected to a vacuum source. This embodiment provides the simplest arrangement of equipment at the front of the shaker and can be operated without a vacuum distributor as shown.

[0148] The use of a screened vacuum enclosure on a downstream screen bed may require additional modification of the vacuum shaker system for optimal operation. In one particular situation, it may be advantageous to have one or more of the upstream screens placed at the same level as the screen of the screened vacuum enclosure so that drill cuttings can vibrate off the upstream screen directly onto the downstream screen of the screened vacuum enclosure. It is expected that most existing screen frames will have a narrower depth than that of the screened vacuum enclosure and this differential depth will pose a problem if it is desired that the upstream and downstream screens are placed at the same level.

[0149] This problem is conveniently addressed by configuring one or more substantially identical screened vacuum enclosures to function solely as screen frames by installing plugs in all of the vacuum ports and placing these modified screened vacuum enclosures on one or more of the upstream screen beds. Since the depth of the screened vacuum enclosures is substantially identical, the levels of all of the screens should be substantially identical. If it is found that the plugs prevent adequate alignment of the adjacent longitudinal outer frame members of adjacent screened vacuum enclosures, the outer frame members may be fitted with gaskets to bridge the gaps between the adjacent screened vacuum enclosures. The manner of constructing and fitting of gaskets to the screened vacuum enclosures is within the knowledge of the person skilled in the art.

[0150] In all example embodiments described herein, the vacuum ports are located on the front side surface of the downstream longitudinal member. Alternative embodiments have ports located on the underside of either the downstream or upstream longitudinal member. The provision of ports in the upper surfaces of the upstream or downstream longitudinal members is also possible, but expected to be less advantageous because of potential interference with the movement of drill cuttings across the screen of the screened vacuum enclosure.

EXAMPLES

Example 1: A Kit for Assembly of Embodiments 1 and 2

[0151 ] As understood by the foregoing description, alternative embodiments of the first and second embodiment of the screened vacuum enclosure may be constructed which employ any number of vacuum ports and vacuum pipes. While the maximum number of vacuum ports and pipes in the embodiments described above is nine ports and nine pipes, the skilled person will recognize that it is possible to design alternative embodiments with more ports and pipes. Such alternatives are also within the scope of the invention. Advantageously, both of the embodiments described above and additional embodiments may be constructed using the example kit described below.

[0152] In the present example, there is provided a kit for assembly of screened vacuum enclosures of embodiments 1 and 2 for use in separating drilling fluid from drill cuttings on a shaker. In one embodiment, the kit comprises outer frame members including two longitudinal outer frame members and two transverse outer frame members and inner frame members including two longitudinal inner frame members and two transverse inner frame members. The kit also includes a covering floor structure designed to substantially cover the bottom of the frame. An adhesive for attaching the floor to the lower surface of the frame and for attaching a commercially obtained screen to the upper surface of the frame may also be provided.

[0153] The transverse outer frame members include a set of notches for holding the ends of inner longitudinal frame members. The two longitudinal inner frame members are each provided with two different sets of openings along their length. One set of openings has two rectangular openings provided to allow passage of the two transverse inner frame members to hold them in place in relation to the inner longitudinal members, thereby forming a rigid double cross-like structure. The other set of openings are round openings provided to hold the vacuum pipes. This double cross-like structure is installed inside the outer frame. The floor is attached either before or after the vacuum pipes are inserted according to the desired configuration. Lastly, the screen is attached. This structure can then be placed on the screen bed of a shaker and the vacuum conduit lines can be attached to the vacuum pipes. The vacuum lines extend to a vacuum distributor which is connected by a main vacuum conduit to a vacuum source and a drilling fluid storage tank.

[0154] An example of a process of assembly of two different embodiments of the screened vacuum enclosure is now described with reference to components and features best illustrated in Figures 3 and 6. (1 ) Align the longitudinal inner frame members 16a and 16b so that their corresponding pairs of square or rectangular holes 20s/20u and 20q/20v are aligned;

(2) Push transverse member 18a through holes 20s/20u and push transverse member 18b through holes 20t/20v. The result of this process yields a rigid double cross-like inner structure;

(3) Assemble the outer frame by connecting the outer frame members 14a, 14b, 14c and 14db at their ends to form a rectangular-shaped outer frame 12.

(4) Insert the inner double-cross structure into the frame 12 by fitting the ends of the longitudinal members 16a and 16b into corresponding notches 22w, 22x, 22y and 22z in the transverse outer frame members 14c and 14d. The free ends of the transverse members 18a and 18b then fit snugly against the inner side walls of the longitudinal outer frame members 14a and 14b. The frame structure 12 is now complete.

(5) Attach the floor 30 to the bottom surfaces of the frame 12.

(6) Insert some or all of the vacuum pipes 28a - 28i into corresponding vacuum ports 26a - 26i to obtain the desired configuration of vacuum pipes. For the embodiment of Figures 1 -3, a vacuum pipe is inserted into each one of the ports and through corresponding holes in the longitudinal inner members to obtain a 9- pipe arrangement 28a - 28i as shown in Figure 3. For the alternative embodiment of Figures 4-6, a vacuum pipe is inserted into alternating vacuum ports such that four vacuum pipes 128b, 128d, 128f and 128h are installed. To prepare this embodiment, it is important to use longitudinal inner members 116a and 116b are which have channels 136a - 136f formed on their lower surfaces to allow vacuum suction to be extended to the middle and rightmost longitudinal areas when the device is in use. These longitudinal members 116a and 116b also have fewer holes for holding vacuum pipes than the longitudinal members 16a and 16b of the nine-pipe embodiment of the screened vacuum enclosure.

(7) Lastly, the screen 32 or 132 is attached to the top surfaces of the frame 12 or

112. (8) Now the vacuum screen enclosure 10 or 110 can be placed on the downstream screen bed of a shaker and attached to a vacuum distributor as described above, with reference to Figures 14A and 14B.

[0155] Certain embodiments of the kit include one or more screens while other embodiments do not include one or more screens. It may be advantageous to omit the screens from the kits because users may already have inventories of appropriate screens at their work locations. In any case, screens are obtainable from commercial manufacturers and need not be included as components of the kit. It is advantageous to assemble the screened vacuum enclosures at or near the work site so that the screened vacuum enclosures may be customized for the conditions at the site. For example, if a particular class of heavier rock cuttings is present in the drilling fluid as it emerges during the drilling operation, operators may elect to attach a heavier screen to the frame of the kit and to use the nine-pipe configuration of the embodiment of Figures 1 to 3.

[0156] The kit may include specific step-by step instructions such as those outlined above, to guide users in assembly of screened vacuum enclosures. The instructions may also include specific guidance for assembly and use of different embodiments with different vacuum pipe configurations when specific conditions are expected.

Example 2: Screened Vacuum Enclosures of Embodiment 3 Compatible with the BRANDT™King Cobra Shaker and the MONGOOSE PRO Shaker

[0157] The BRANDT™ King Cobra shakers produced by Brandt of Houston, TX, USA and marketed by National Oilwell Varco and the MONGOOSE PRO shakers marketed by Ml Swaco/Schumberger are in wide use in drilling operations. It is advantageous to produce screened vacuum enclosures in accordance with specific embodiments of the present invention which are compatible with these shakers.

[0158] The skilled person is to understand that the dimensions of the example embodiments described below are not to be construed as limiting, but are provided simply by way of illustrating certain embodiments with specific examples. Alternative embodiments will have dimensions which vary from these examples if they are designed to be compatible with any other shaker systems. Alternative dimensions can be determined by the skilled person without undue experimentation. [0159] Shown in Tables 1 to 3 are lists of dimensions for screened vacuum enclosures of embodiments 3 to 5 optimized for use in conjunction with the BRANDT King Cobra shaker and a second screened vacuum enclosure optimized for use in conjunction with the MONGOOSE PRO shaker.

Table 1 : Selected Dimensions and Features for Screened Vacuum Enclosures

(Embodiment 3) Configured for Use with the KING COBRA Shaker and the

MONGOOSE PRO Shaker

Table 2: Selected Dimensions and Features for Screened Vacuum Enclosures

(Embodiment 4) Configured for Use with the KING COBRA Shaker and the

MONGOOSE PRO Shaker

Table 3: Selected Dimensions and Features for Screened Vacuum Enclosures

(Embodiment 5) Configured for Use with the KING COBRA Shaker and the

MONGOOSE PRO Shaker

Length of single slot in front frame

member (inches) 13 1 /4 13 1 /4

Equivalents and Scope

[0160] Other than described herein, or unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages, such as those for amounts of materials, elemental contents, times and temperatures, ratios of amounts, and others, in the following portion of the specification and attached claims may be read as if prefaced by the word "about" even though the term "about" may not expressly appear with the value, amount, or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0161] Any patent, publication, internet site, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated material does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material.

[0162] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. [0163] While this invention has been particularly shown and described with references to embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.