TECHNICAL FIELD

The presently disclosed subject matter relates to a ball insertion device for use in oil and gas wells.

BACKGROUND

Oil and gas wells are typically subjected to fracturing or other stimulation procedures by isolating zones of interest in the wellbore by use of packers and the like. Thereafter, a treatment fluid or fracturing fluid is forced into the isolated zone at an elevated treatment pressure. In a typical fracturing procedure for a cased wellbore, for example, the casing of the well is first perforated to allow oil and/or gas to flow into the wellbore. Thereafter, a fracturing fluid is then pumped into the wellbore and through the perforations into the formation. Such treatment opens and/or enlarges drainage channels in the formation, enhancing the producing ability of the well. For open holes that are not cased, stimulation is carried out directly in the zone intervals without the need for perforating casing.

Frequently, a series of packers in a packer arrangement may be inserted into the wellbore, wherein the packers are located at intervals for isolating one zone from an adjacent zone. To selectively engage a packer, a ball ( a so-called "frac ball') is typically introduced into the wellbore so as to block fluid flow through the packer, which creates an isolated zone up-hole from the blocked packer so that a fluid treatment or stimulation may be performed on that isolated interval. Once the previously isolated (lower) zone has been stimulated, a subsequent ball is dropped to block off a subsequent packer that is positioned up-hole from the previously blocked packer, so as to create another isolated zone up-hole of the second blocked packer. This second isolated zone is then fractured or treated. The process is continued until all of the desired zones have been stimulated and/or fractured. Typically the balls range in diameter from a smallest diameter ball, which is suitable for blocking fluid flow through the most downhole packer, to the largest diameter ball, which is suitable for blocking fluid flow through the most up-hole packer.

Equipment for fracturing, such as a so-called "frac head," is typically provided at the surface of a well so that fracturing operations may be conducted. The frac head includes fluid connections for introducing fracturing fluids, which may include proppants and like, into the well bore, and ultimately into the formation during the fracturing process. There are various prior art systems that have been employed for introducing the frac balls into a wellbore. Some are very complex and involve a complex arrangement of various valves and fittings that are operated so as to introduce the frac balls into the wellbore. Such complexity may lead to additional costs, operator errors, down time due to maintenance of the complex arrangement of valves and fittings and/or failure of one or more of the pieces of equipment.

The present application is directed to a novel ball insertion device with a ball storage and delivery track for use in oil and gas wells thai may eliminate or at least minimize some of the problems noted above.

SUMMARY

The following presents a simplified summary of the subject matter disclosed herein in order to provide a basic understanding of some aspects of the information set forth herein. This summary is not an exhaustive overview of the disclosed subject matter. It is not intended to identify key or critical elements of the disclosed subject matter or to delineate the scope of various embodiments disclosed herein. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.

The present application is directed to a novel ball insertion device for use in oil and gas wells. In one illustrative embodiment, the ball inserter device comprises, among other things, a ball receiving opening that is adapted to receive the ball and a ball insertion opening that is adapted to have the ball exit therefrom, wherein the ball insertion opening intersects the ball receiving opening. In this embodiment, the device further comprises a removable upper plug comprising at least one seal positioned on the upper plug, wherein at least a portion of the upper plug is adapted to be positioned in the ball receiving opening such that the at least one seal sealingly engages an inner surface of the ball receiving opening and a ball inserter piston having a rod that is axially aligned with the ball insertion opening.

Another illustrative embodiment of a ball inserter device disclosed herein comprises, among other things, a ball receiving opening that is adapted to receive the ball, a ball insertion opening that is adapted to have the ball exit therefrom, wherein the ball insertion opening intersects the ball receiving opening, and a removable upper plug that is adapted to be positioned in the ball receiving opening such that it sealingly engages an inner surface of the ball receiving opening, and wherein the removable plug is adapted to be positioned in the ball receiving opening by axial movement of the removable plug within the ball receiving opening. In this example, the device also comprises a plurality of ball insertion isolation valves each of which are positioned in the ball insertion opening, wherein, when the plurality of ball insertion isolation valves are in an open position, the ball may pass through the plurality of ball insertion isolation valves and when the plurality of ball insertion isolation valves are in a closed position, the ball is blocked from passing through the plurality of ball insertion isolation valves and a ball inserter piston having a rod that is axially aligned with the ball insertion opening.

Yet another illustrative embodiment of a ball inserter device disclosed herein comprises, among other things, a ball receiving opening that is adapted to receive the ball, a non-obstructed ball insertion opening that is adapted to have the ball exit therefrom, wherein the non-obstructed ball insertion opening intersects the ball receiving opening and a removable upper plug that is adapted to be positioned in the ball receiving opening such that it sealingly engages an inner surface of the ball receiving opening. In this embodiment, the device also comprises a lower ball-receivmg plug that is adapted to be sealingly positioned in the ball receiving opening below the removable plug, the ball-receiving plug having a ball receiving opening defined therein for receiving the ball and a ball inserter piston having a rod that is axially aligned with the ball insertion opening.

One illustrative method disclosed herein for using a ball inserter device comprises includes, among other things, closing a plurality of ball insertion isolation valves positioned within a ball insertion opening such that a ball is blocked from passing through the plurality of ball insertion isolation valves, removing a removable plug entirely from within a ball receiving opening so as to thereby expose the ball receiving opening and inserting the ball through the ball receiving opening and into the ball insertion opening and re-positioning the removable plug to its sealing position within the ball receiving opening. In this example, the method also comprises after re-positioning the removable plug, opening the ball insertion isolation valves such that the ball may pass through the ball insertion isolation valves and actuating a ball inserter piston such that a rod within the ball inserter piston moves from a retracted position to an extended position so as to push the ball through the ball insertion isolation valves, out of the ball insertion opening and into a well bore. Another illustrative method for using a ball inserter device disclosed herein includes, among other things, removing a removable plug entirely from within a ball receiving opening in a body of the ball inserter device so as to thereby expose the ball receiving opening, inserting a ball through the ball receiving opening and into a ball receiving opening defined in a ball receiving plug and re-positioning the removable plug to its sealing position within the ball receiving opening in the body of the device. In this example, the method further comprises after re-positioning the removable plug, actuating a push rod to an extended position such that the push rod engages an upper surface of the ball-receiving plug and dislodges the lower ball- receiving plug from its sealing position within the ball receiving opening in the body of the device and moves the ball-receiving plug into the non-obstructed ball insertion opening wherein an axis of the ball-receiving opening in the ball-receiving plug is axially aligned with an axis of the non-obstructed ball insertion opening and actuating the ball inserter piston such that a rod within the ball inserter piston moves from a retracted position to an extended position so as to push the ball out of the ball receiving opening in the ball receiving plug, through the non- obstructed ball insertion opening and into the well bore.

BRTEF DESCRIPTION OF THE DRAWINGS

Certain aspects of the presently disclosed subject matter will be described with reference to the accompanying drawings, which are representative and schematic in nature and are not to be considered to be limiting in any respect as it relates to the scope of the subject matter disclosed herein:

Figure 1 depicts various illustrative examples of a novel ball insertion system for use in oil and gas wells disclosed herein;

Figures 2-9 depict one illustrative example of a novel ball insertion system comprising a novel ball insertion device and a novel ball storage and delivery track as well as an illustrative operational sequence using such a system: and Figures 10-21 depict another illustrative example of a novel ball insertion system comprising a novel ball insertion device and novel ball storage and delivery track as well as an illustrative operational sequence using such a system. While the subject matter disclosed herein is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the disclosed subject matter to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosed subject matter as defined by the appended claims.

DESCRIPTION OF MBODIMENTS

Various illustrative embodiments of the disclosed subject matter are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

The present subject matter will now be described with reference to the attached figures. Various structures, systems and devices are schematically depicted in the drawings for purposes of explanation only and so as to not obscure the present disclosure with details that are well known to those skilled in the art. Nevertheless, the attached drawings are included to describe and explain illustrative examples of the present disclosure. The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art. No special definition of a term or phrase, i.e., a definition that is different from the ordinary and customary meaning as understood by those skilled in the art, is intended to be implied by consistent usage of the term or phrase herein. To the extent that a term or phrase is intended to have a special meaning, i. e. , a meaning other than that understood by skilled artisans, such a special definition will be expressly set forth in the specification in a definitional manner that directly and unequivocally provides the special definition for the term or phrase. One illustrative ball insertion system 100 will no be described with reference to Figures 1 -9. The ball insertion system 100 generally includes a novel ball insertion device 101 and a novel ball storage and delivery track 102. The bail insertion system 100 will be disclosed in the context of using the ball insertion system 100 to introduce frac balls into a well during a well fracturing operation. However, as will be appreciated by those skilled in the art after a complete reading of the present application, the novel ball insertion system 100 disclosed herein may be employed in a variety of applications as it relates to operations performed on oil and gas wells.

Figure 1 is a partial cross-sectional elevation view depicting one illustrative example of how the ball insertion system 100 may be employed and arranged with respect to a plurality of pieces of equipment positioned above an illustrative wellhead 10. The wellhead 10 provides access to a wellbore (not shown) (cased or un-cased) in an earthen formation. In the depicted example, there are several items of equipment positioned above the wellhead 10: a tubing head 12, a lower master valve 14, a flow outlet valve 16, an upper master valve 18 and a frac head 20. In the depicted example, a spool (e.g., a tee) 21 is positioned between the lower and upper master valves 14, 18, and one illustrative example, the ball insertion system 100 is removably coupled to the spool 21 by a flanged connection 23. A bore 25 is defined in the spool 21 and it is axially aligned with other bores (not shown) in the various pieces of equipment above and below the spool 21. The bore 25 is in fluid communication with the wellbore that extends into the formation. In the depicted example, the ball insertion system 100 is coupled to the spool 21.

However, in other applications, the spool 21 may be omitted and at least some portions of the bail insertion system 100 may be coupled to or formed integrally with another item of equipment positioned above the wellhead 10. Different sized spools 21 may also be provided with different bores 25 therein for different sized wells, wherein ball insertion system 100 is a universal device that may be used with each of the different sized spools.

Figure 2 is a cross-sectional elevation view taken through the ball insertion system 100. Figure 3 is a plan view of the ball insertion system 100. As shown in Figures 2-3, one illustrative example of the ball insertion device 101 of the ball insertion system 100 is generally comprised of an inserter body 30 having a ball insertion opening 32 and a ball receiving opening

34 defined therein, a plurality of ball insertion isolation valves 36A, 36B (collectively referred to using the numeral 36), a ball inserter piston 38, an inserter vent valve 40, an pressure monitoring line 42, a plug 44, a seal integrity line 46, a nut 48 with schematically depicted external threads 48A (only shown in Figure 2) formed on the outer surface of the nut 48, a housing 50 with schematically depicted intemal threads 5 OA (only shown in Figure 2) formed on the intemal surface of the housing 50 for the entire axially length of the housing 50, a shaft 52 and a rotary driver 54. The ball insertion opening 32 is in fluid communication with the bore 25 defined in the spool 21 and, in one embodiment, defines a substantially constant diameter opening from the piston 38 to the bore 25. The ball receiving opening 34 is in fluid communication with the ball insertion opening 32. The ball insertion opening 32 provides the conduit by which frac balls 55 from the ball storage and delivery track 102 will be delivered to the ball insertion opening 32 and thereafter inserted into the bore 25 by actuation of the piston 38, as described more fully below. In general, the size of the openings 32, 34 may vary depending upon the particular application. In one embodiment, the ball insertion opening 32 and the ball receiving opening 34 will normally have the substantially the same intemal diameter and they may be sized to accommodate the largest ball 55 that will be inserted into a range of wells where the ball insertion system 100 is expected to be deployed, e.g. , they may have an intemal diameter of about 4 inches in one illustrative embodiment. Of course, balls 55 having a lesser diameter than the inside diameter of the ball insertion opening 32 and the ball receiving opening 34 may be inserted into a well using the novel ball insertion system 100 disclosed herein, e.g., 2 inch diameter balls 55 may be inserted using a ball insertion device 101 with a ball insertion opening 32 having a diameter of 4 inches. In one example, with the ball insertion opening 32 and the ball receiving opening 34 both having an internal diameter of 4 inches, the ball insertion system 100 disclosed herein may be employed to insert frac balls 55 having diameters that fall within the range of about 0.5 - 4 inches. The plug 44 is adapted to be positioned in and withdrawn from the ball receiving opening 34 by axial movement of the plug 44 within the ball receiving opening 34. In one embodiment, the plug 44 may be moved by actuation of the rotary driver 54, as described more fully below. When the plug 44 is positioned in the ball receiving opening 34, a plurality of seals 56, 58 positioned on the plug 44 sealingly engage the inner surface of the ball receiving opening 34. The type and number of seals may vary depending upon the particular application, e.g., the seals 56, 58 may be O-ring type seals. In general, the each of the seals 56, 58 is pressure rated to at least IX the working pressure of the well. The seal integrity line 46 is provided to check that the seals 56, 58 are performing their sealing function. The nut 48 is fixedly coupled to the rod 52 by a keyed connection (not shown). The nut 48 is bolted to the plug 44 by a single bolt in the center. This arrangement allows the nut 48 to rotate, but limits the movement of the plug 44 to translational movement. The external threads 48A that are formed on the nut 48 are adapted to mate with the internal threads 5 OA formed on the housing 50. When the rotary driver 54 is actuated, the rod 52 rotates in a first direction thereby causing the nut 48 to travel vertically upward within the housing 50 and retract the plug 44 from the ball receiving opening 34. The plug 44 may be inserted into the ball receiving opening 34 by rotating the rotary driver 54 in the opposite direction to the first direction so as to causes the nut 48 to travel downward within the housing 50. The rotary driver 54 may be any type of device, e.g., an electric motor or hydraulic motor with appropriate gears (not shown) that are operatively coupled to the rod 52. Collectively, the housing 50, the nut 48, the rod 52 and the rotary driver 54 constitute the means for moving the removable plug 44 into and out of the ball receiving opening 34. The ball insertion isolation valves 36 may be any type of valve suitable for performing the isolation function of blocking the ball insertion opening 32 when they are in a closed position and allowing a frac ball 55 to pass through the ball insertion opening 32 when the ball insertion isolation valves 36 are in an open position. In one illustrative example, the ball insertion isolation valves 36 may be a gate valve or a ball valve. In one illustrative embodiment, each of the ball insertion isolation valves 36 may have a pressure rating of at least IX the working pressure of the well. In another embodiment, the ball insertion device 101 may comprise only a single ball insertion isolation valve 36 that is positioned in the ball insertion opening 32. The ball insertion isolation valves 36 may be actuated in any desired manner, e.g., manually, hydraulically or electrically. In the example depicted in the drawings, the ball insertion isolation valves 36 are gate valves. In the depicted example, the ball insertion isolation valves 36 are each provided with pressure balancing means for reducing the magnitude of the actuating forces needed to open or close the valves 36. Such pressure balancing means are well known to those skilled in the art. In the examples shown in the drawings, each of the valves 36 comprise a gate 37 with an opening (not shown) defined therein. When the ball insertion isolation valves 36 are in their closed positions, the gates 37 blocks the ball insertion opening

32. The ball insertion isolation valves 36 can be actuated to their open position such that the openings in the gates 37 are in alignment with the ball insertion opening 32. When the ball insertion isolation valves 36 are closed, the ball insertion device 101 is isolated from pressure within the well. In terms of relative positioning based upon the direction of travel of a frac ball 55 through the ball insertion device 101, the ball insertion isolation valves 36A, 36B are positioned in the ball insertion opening 32 downstream of the ball receiving opening 34 and upstream of the final ball outlet 33 of the ball insertion system 100. The ball inserter piston 38 may be a pneumatic or hydraulic double-acting piston. The ball inserter piston 38 has a ball engagement attachment 38A that is removably coupled to the rod 38B of the piston 38. In the depicted example, the piston 38 is mechanically coupled to the inserter body 30 via a flanged connection 41 such that the axis of the rod 38B of the piston 38 is axially aligned with the ball insertion opening 32. In one example, the ball engagement attachment 38A may be made of a relatively hard material, such as steel, and it may have a substantially planar engagement face 38C that is adapted to engage a frac ball 55 during the ball insertion process. The ball inserter piston 38 should have a sufficient stroke such that, when the piston rod 38B is fully extended, the engagement face 38C of the engagement attachment 38 A may be positioned at least a portion of the way into the bore 25 to insure that the ball 55 has been properly inserted into the bore 25. Of course, the total stroke length of the ball inserter piston 38 (in absolute length terms) may vary depending upon the particular application and the size of the components of the ball insertion system 100. Control of the positional location of the rod 38B of the ball inserter piston 38 (i.e., from fully retracted to fully extended) may be controlled by various known techniques, e.g., a plurality of limit switches (not shown).

It should also be noted that the ball insertion device 101 may be provided with various relief valves or mechanisms that provide a means to vent pressure from within various portions of the ball insertion device 101. For example, the relief valve 40 is in fluid communication with both the ball insertion opening 32 and the ball receiving opening 34 at a location that is upstream of the ball insertion isolation valves 36A, 36B and downstream of the plug 44. With the plug

44 in its installed position in the ball receiving opening 34, and with the ball insertion isolation valves 36A, 36B closed, the pressure relief valve 40 may be opened to relieve any pressure that may be trapped between the plug 44 and the closed ball insertion isolation valves 36A, 36B. The pressure monitoring line 42 is defined in body 30 at a location that is upstream of the ball insertion isolation valves 36A, 36B. A pressure gage or alarm (not shown) or the like may be operatively coupled to the line 42 to insure that the ball insertion isolation valves 36A, 36B are performing their sealing function when they are in their closed position. Additionally, the ball insertion device 101 may be provided with ball detection means (not shown) to detect when a frac ball 55 has properly landed within the ball receiving opening 34. In one illustrative embodiment, the detection means may comprise one or more acoustic sensors.

The ball storage and delivery track 102 of the ball insertion system 100 will now be further described. However, as will be appreciated by those skilled in the art after reading the present application, the ball insertion device 101 may be employed in situations that do not involve use of the ball storage and delivery track 102 disclosed herein. For example, the ball insertion device 101 may be employed with other types of ball storage and delivery mechanisms. In other applications, the ball insertion device 101 may be employed in situations where there is no ball storage and delivery mechanism, i.e., frac balls 55 may be inserted manually into the well using just the ball insertion device 101.

In this example, the ball storage and delivery track 102 takes the form of a carousel-type device. With reference to Figures 2-7, in the illustrative example depicted herein, the ball storage and delivery track 102 comprises a generally oval-shaped housing track comprising a bottom potion 60, a cover 62, and a plurality of ball carriers 64, each of which have a ball opening 65 defined therein that is adapted to receive a frac ball 55. Of course, the shape and configuration of the track may vary from that depicted herein and tracks having different configurations may be employed in different settings or applications. With reference to Figures 3, 4 and 7, in one illustrative embodiment, adjacent ball carriers 64 are coupled to one another via a plurality of chain links 72 so as to thereby form a continuous chain of ball carriers 64. The ball storage and delivery track 102 comprises a means for advancing the chain of ball carriers 64. With reference to Figures 3 and 4, the chain of ball carriers 64 may be advanced within the bottom portion 60 of the housing by a means that includes a piston 68. A pawl 70 that is attached to the end of a rod 69 of the piston 68 is adapted to engage an edge 64A (see Figure 7) of one of the ball carriers 64 when the piston 68 is actuated, thereby moving the chain of ball carriers 64 forward within the bottom portion 60 of the track. Each stroke of the piston 68 advances the chain of ball carriers 64 a distance equivalent to one ball carrier 64. An opening or slot (not shown) is formed in the sidewall of the lower portion 60 of the track in the area of the piston 68 to permit the pawl 70 to engage the ball carriers 64. In some embodiments, the bottom surface of the ball carriers 64 may be provided with small bumps on the corners of the ball carrier 64 so as to reduce the sliding frictional force where the continuous chain of the ball carriers 64 is advanced within the track. As shown in Figure 5, the bottom portion 60 of the track comprises a ball outlet opening 63. A corresponding opening 67 is provided in the cover 62 to allow passage of the plug 44 there through. The axis of the ball outlet opening 63 is aligned with and positioned vertically above the ball receiving opening 34. Additionally, as shown in Figure 6, the housing 50 has track opening 76 defined therein that is large enough to accommodate the size of the assembled bottom portion 60 and the cover 62 of the track. Also note that the axis 78 of the vertical opening in the housing 50 is axially aligned with the opening 63 in the track and the ball receiving opening 34. The physical size of the components of the ball storage and delivery track 102 and the number of frac balls 55 that may be positioned within the ball storage and delivery track 102 may vary depending upon the particular application. In one illustrative embodiment, the ball storage and delivery track 102 is adapted to hold thirty frac balls 55 each of which may vary may be up to about 4.5 inches in diameter. Of course, not all of the balls 55 positioned in the ball storage and delivery track 102 need to have the same diameter, i. e. , the ball storage and delivery track 102 may hold balls 55 of differing diameters if appropriate for the particular application. The illustrative example depicted herein wherein the frac balls 55 are shown as all having the same diameter is provided just by way of example and should not be considered to be a limitation of the presently disclosed subject matter.

Since the ball storage and delivery track 102 is not exposed to well bore pressure, the components of the ball storage and delivery track 102 may be made of a variety of different materials, e.g., aluminum, plastic, steel, etc. Of course the means for advancing the chain of ball carriers 64 may vary depending upon the particular application. For example, the piston 68 could be replaced with a motor (either electric or hydraulic) and various gears that could engage the chain of ball carriers 64. Additionally, in lieu of the individual links 72 that couple the carriers 64 to one another, the carriers 64 could be modified so as to allow a traditional chain to be coupled to the carriers 64 on the inside surface of the carriers 64. Other options for advancing the chain of the ball carriers 64 will be recognized by those skilled in the art after a complete reading of the present application.

Figures 8-9 depict aspects of one illustrative operational sequence of the bail insertion system 100 disclosed herein that includes the above-described ball insertion device 101 and ball storage and delivery track 102 for use during the insertion of a frac ball 55 into the well bore 25 during fracturing operations performed on an oil/gas well. The ball storage and delivery track 102 is coupled to the ball insertion device 101 such that the track extends through the track opening 76 defined in housing 50. The track is positioned such that the axis of the ball outlet opening 63 in the bottom of the track is aligned with and positioned vertically above the ball receiving opening 34. The vertical opening in the housing 50 is also axially aligned with the opening 63 in the track and the ball receiving opening 34.

Starting from the situation shown in Figure 2, where the a portion of the plug 44 is positioned in the opening 65 of the ball carrier 64A that is positioned above the ball outlet opening 63 (i.e., the ball carrier 64A does not contain a frac ball 55) and a frac ball 55 is not present in either the ball insertion opening 32 or the ball receiving opening 34 and the plug 44 is in its closed and sealed position (as shown in Figure 2) within the ball receiving opening 34 (i.e., the rod 52 is in its fully extended position), the first operation will be to close the ball insertion isolation valves 36A, 36B so as to isolate the ball insertion device 101 from well bore pressure. Thereafter, the vent valve 40 may be opened to vent any pressure trapped between the closed plug 44 and the closed ball insertion isolation valves 36A, 36B. A pressure gage or alarm (not shown) or the like may be operatively coupled to the pressure monitoring line 42 and monitored at all times during the ball insertion process to insure that the ball insertion isolation valves 36A, 36B are performing their sealing function when they are in their closed position. The seal integrity line 46 may be monitored or checked at any time during the process when the plug 44 is in its installed position in the ball receiving opening 34 to insure that the seals 56, 58 are performing their sealing function.

With reference to Figure 8, one illustrative process sequence for inserting a particular frac ball 55A that is positioned in the ball carrier 64B and resting on the inner surface of the bottom 60 of the track will now be described. First, the rotary driver 54 is rotated so as to retract the plug 44 from its installed positon in the ball insertion opening 32 to its fully retracted position within the housing 50 above the cover 62 of the track. Retraction of the plug 44 from the opening 65 in the ball carrier 64A means that the chain of ball carriers 64 within the track is free to be advanced within the track. At that time, the piston 68 is actuated and the pawl 70 engages one of the ball carriers 64 to advance the chain of ball carriers 64 such that the ball carrier 64B is positioned above the ball outlet 63 in the track and above the ball receiving opening 34. At that time, the ball 55A that was in the ball carrier 64B falls through the ball outlet 65 where it lands in the ball insertion opening 32, as depicted in Figure 8. Note, that in advancing the chain of ball carriers 64, the ball carrier 64A has advance to the right from its initial position shown in Figure 2.

With reference to Figure 9, the rotary driver 54 is actuated so as to cause the plug 44 to move downward through the opening 65 in the ball carrier 64B; through the ball outlet 63 in the track and into if fully seated and installed position within the ball receiving opening 34. Next, the seal integrity line 46 may be monitored or checked to insure that the seals 56, 58 are performing their sealing function. Thereafter, the ball insertion isolation valves 36A, 36B are opened. Then, the ball inserter piston 38 may be actuated and its rod 38B fully extended so as to push the frac ball 55A down the ball insertion opening 32, through the open valves 36A, 36B, out of the outlet 33 and into the well bore 25. At that point, the ball inserter piston may be returned to its fully retracted position and the valves 36A, 36B may be closed. Any pressure trapped between the valves 56A, 56B and the plug 44 may be vented by opening the vent valve 40. This process may be repeated as additional frac balls 55 are introduced into the well bore 25.

Figures 10-21 depict another illustrative example of a novel ball storage and delivery ball insertion system 100 disclosed herein as well as an illustrative operational sequence using such a system. This embodiment of the ball insertion system 100 generally includes a different and novel ball insertion device 103 and the above-described novel ball storage and delivery track 102. Figure 10 is a cross-sectional elevation view taken through the ball insertion system 100. Figure 11 is a plan view of the ball insertion system 100.

As shown in Figures 10-11, one illustrative example of the ball insertion device 103 is generally comprised of the above-described inserter body 30 having a ball insertion opening 32 and a ball receiving opening 34 defined therein, the above-described ball inserter piston 38, an upper plug 80, a lower ball-receiving plug 82, a spring 84, the above-described nut 48 (with external threads formed on the outer surface of the nut 48, the above-described housing 50 (with internal threads 48 A formed on the internal surface of the housing 50), the above-described shaft 52 and the above-described rotary driver 54. The ball insertion device 103 further comprises a lower ball-receiving plug seal integrity line 92, an upper plug seal integrity line 96 and a pressure port 94 that will allow well bore pressure to be introduced into the space between the upper plug 80 and the lower ball-receiving plug 82 as described more fully below. The plug 80 is adapted to be positioned in and withdrawn from the ball receiving opening 34 by axial movement of the plug 80 within the ball receiving opening 34. The device 103 also comprises a push rod 85 that is located axially within an opening the shaft 52. The push rod 85 may be moved axially within the shaft 52 as described more fully below. Note that, unlike the previous embodiment of the ball insertion device 102, in this embodiment, there are no isolation valves (like the above-described isolation valves 36A, 36B) positioned in the ball insertion opening 32 of the ball insertion device 103. That is, in this embodiment, the ball insertion opening 32 is a non-obstructed ball insertion opening. Thus, as used in this application and in the claims, when it is stated that the device comprises a "non-obstructed ball insertion opening" is should be understood to mean the opening is free of any valve that may be actuated to block the ball insertion opening.

Figure 10 depicts the ball insertion device 103 with the upper plug 80 in its fully retracted position within the housing 50. Figure 12 is an enlarged view of the upper plug 80 shown in Figure 10. With reference to Figure 10, by actuation of the rotary driver 54, the upper plug 80 was withdrawn from its previous sealing engagement with the inner surface of the ball receiving opening 34. That is, the upper plug 80 was withdrawn through the ball outlet 63 in the bottom 60 of the ball track, through the opening 65 in the ball carrier 64A and through the opening 67 in the cover 62 of the ball carousel. This positions the upper plug 80 in its fully retracted position within the housing 50 and exposes the ball receiving opening 34. As best seen in Figure 12, the upper plug 80 has a recess 80A defined therein that is adapted to receive the shaft portion of the push rod 85. The push rod 85 has an end surface 85 A that is adapted to engage lower ball-receiving plug 82, as described more fully below. In one illustrative embodiment, the seals 81, 83 are positioned on the upper plug 80. When the upper plug 80 is positioned in its installed and sealed position within the ball receiving opening 34, the seals 81, 83 sealingly engage the inner surface of the ball receiving opening 34. The type and number of seals may vary depending upon the particular application, e.g., the seals 81, 83 may be O-ring type seals. In general, the each of the seals 81, 83 is pressure rated to at least IX the working pressure of the well. The upper plug seal integrity line 96 is provided to check that the seals 81, 83 are performing their sealing function when the upper plug 80 is positioned within the ball receiving opening 34, as described more fully below.

Figures 13A-C and Figure 10 will be referenced to describe more aspects of the lower ball-receiving plug 82. Figures 13A, 13B and 13C are, respectively, a plan view, a cross- sectional side view and a perspective view of one illustrative embodiment of the lower ball- receiving plug 82 disclosed herein. The lower ball-receiving plug assembly 82 generally comprises a ball-receiving opening 82A that is adapted to receive a frac ball 55 positioned therein. The ball-receiving opening 82A has a bottom rounded surface 82B and sidewalls 82C, each or which have an upper surface 82D. The opening 82A has an axis 82E that is adapted to be substantially axially aligned with the axis of the non-obstructed ball insertion opening 32 when the lower ball-receiving plug assembly 82 is urged into the non-obstructed ball insertion opening 32 by actuation of the push rod 85 just prior to actuating the ball inserter piston 38 to insert the frac ball 55 into the well bore 25, as described more fully below. Rotation of the lower ball-receiving plug 82 about an axis that includes the centerline of the shaft of the push rod 85 may be accomplished by any of a variety of known mechanical means (not shown) such as an alignment pin that prevents such rotation. The lower ball-receiving plug 82 has a bottom surface 82F that is adapted to engage the spring 84. With reference to Figure 10, in one illustrative embodiment, the seals 88, 90 are positioned on the outer surface of the lower ball- receiving plug 82. When the lower ball-receiving plug 82 is positioned in its initial sealed position within the ball receiving opening 34, the seals 88, 90 sealingly engage the inner surface of the ball receiving opening 34. The spring 84 is biased so as to urge the lower ball-receiving plug 82 to its sealed position within the ball receiving opening 34. The type and number of seals may vary depending upon the particular application, e.g., the seals 88, 90 may be O-ring type seals. In general, the each of the seals 88, 90 is pressure rated to at least IX the working pressure of the well. The lower ball-receiving plug seal integrity line 92 is provided to check that the seals 88, 90 are performing their sealing function when the lower ball-receiving plug 82 is positioned within the ball receiving opening 34, as described more fully below.

Figure 14 is an enlarged cross-sectional view of an alternative embodiment of the lower ball-receiving plug 82 with a different sealing arrangement. In this example, a seal recess 34A is define in the bore of the ball receiving opening 34 and a sealing lip 82A is defined on the lower ball-receiving plug 82. The seal recess 34A has a slightly larger diameter than that of the primary bore of the ball receiving opening 34 so as to accommodate upper and lower compression packings 101, 103 positioned in the seal recess 34A. The sealing arrangement is pressure intensified when pressurized fluid is present in the well bore 25, as well bore pressure may be supplied to the compression packings 101 and 103 via a pressure line 105. The magnitude of the pressure supplied via the line 105 may vary depending upon the particular application. Figure 15 is an enlarged cross-sectional view of yet another alternative embodiment of the lower ball-receiving plug 82 with a different sealing arrangement. In this example, the seal recess 34A is define in the bore of the ball receiving opening 34 and a recess 82X is defined in the bottom surface 82F of the lower ball-receiving plug 82. The recess 82X is adapted to receive a packing energizing body 107. The packing energizing body 107 has a bottom lip 107 A and a bottom surface 107F. The above-described compression seals 101, 103 are positioned in the space defined by the outer surface of the packing energizing body 107, the inner surface of the seal recess 34 A, the lower surface 82F of the lower ball-receiving plug 82 and the lip 107A. As before this sealing arrangement may be pressurized intensified by supplying pressurized fluid from the well bore 25 to the seal recess 34A between the compression packings 101, 103 via the pressure line 105. The magnitude of the pressure supplied via the line 105 may vary depending upon the particular application. The bottom surface 107F of the packing energizing body 107 is adapted to engage the spring 84. As shown in Figure 10, the spring 84 is adapted to engage the bottom surface 82F of the lower ball-receiving plug 82 to maintain the lower ball-receiving plug 82 in its initial position shown in Figure 10. The spring 84 may be secured within an opening 30X defined in the body 30 by use of a flanged connection 86. The opening 30X is axially aligned with the axis of the ball receiving opening 34. The spring constant of the spring 84 may vary depending upon the particular application.

Figures 16-21 depict aspects of one illustrative operational sequence of the bail insertion system 100 disclosed herein that includes the ball insertion device 103 and the above-described ball storage and delivery track 102 for use during the insertion of a frac ball 55A into the well bore 25 during fracturing operations performed on an oil/gas well. As before, the ball storage and delivery track 102 is coupled to the ball insertion device 103 such that the track extends through the track opening 76 defined in housing 50. The track is positioned such that the axis of the ball outlet opening 63 in the bottom of the track is aligned with and positioned vertically above the ball receiving opening 34. The vertical opening in the housing 50 is also axially aligned with the ball outlet opening 63 in the track and the ball receiving opening 34.

With reference to Figure 16, the first step involves accessing the lower ball-receiving plug seal integrity line 92 to insure that the seals 88, 90 are performing their intended sealing function. After the viability of the seals 88, 90 is confirmed, the rotary driver 54 was actuated so as to cause the rod 52 to rotate and thereby retract the upper plug 80 from its installed and sealed positon in the ball receiving opening 34 to its fully retracted position within the housing 50 above the cover 62 of the track. The retraction of the plug 80 exposes the ball receiving opening 34. The retraction of the upper plug 80 from the opening 65 in the ball carrier 64A also means that the chain of ball carriers 64 within the track is free to be advanced within the track. At that time, the piston 68 is actuated and the pawl 70 engages one of the ball carriers 64 to advance the chain of ball carriers 64 such that the ball carrier 64B is positioned above the ball outlet 63 in the track and above the ball receiving opening 34. At that time, the ball 55A that was in the ball carrier 64B falls through the ball outlet 65 where it lands in ball-receiving opening 82A defined in the lower ball-receiving plug 82. At this time, the spring 84 remains in its initial state wherein it exerts an upward force on the lower plug 82 so as to urge it into is sealed position within the ball receiving opening 34, as shown in Figure 16. During this process operation, the seals 88, 90 on the lower ball-receiving plug 82 provide pressure barriers against well bore pressure. Note, that in advancing the chain of ball carriers 64, the ball carrier 64A has advance to the right from its initial position shown in Figure 10.

With reference to Figure 17, the rotary driver 54 is actuated so as to cause the upper plug 80 to move downward through the opening 65 in the ball carrier 64B, through the ball outlet 63 in the track and into its fully seated and installed position within the ball receiving opening 34. The lower ball-receiving plug 82 remains in its initial position shown in Figure 16 during the process of re-positioning the upper plug 80 in the ball receiving opening 34. Next, the upper plug seal integrity line 96 was monitored or checked to insure that the seals 81, 83 positioned on the upper plug 80 are performing their sealing function. Thereafter, well bore pressure is supplied to the space between the lower ball-receiving plug 82 and the upper plug 80 via the pressure port 94 so as to balance the pressure across the lower ball-receiving plug 82.

Figure 18 depicts the ball insertion device 103 after the push rod 85 is extended downward through the opening 52D in the shaft 52. As depicted, the end surface 85A of the push rod 85 engages the upper surface 82D of the sidewalls 82C of the lower ball-receiving plug 82. Extending the push rod 85 forces the lower ball-receiving plug 82 out of its position in the ball-receivmg opening 34 and moves the lower ball-receiving plug 82 into the non-obstructed ball insertion opening 32 and the opening 30X. The downward movement of the lower ball- receiving plug 82 also compresses the spring 84. In this position, the axis 82E of the opening 82A in the lower ball-receiving plug 82 is substantially axially aligned with the axis of the non- obstructed ball insertion opening 32 and with the long axis of the ball inserter piston 38. The push rod 85 may be extended in any desired manner, e.g., by coupling a double acting hydraulic cylinder (not shown) to the upper end of the push rod 85, by coupling another motor (not shown) with appropriate gearing such that rotation of the motor causes translational movement of the push rod 85, or it can even be operated manually, etc.

Figure 19 depicts the ball insertion device 103 after the ball inserter piston 38 has been actuated and its rod 38B fully extended so as to push the frac ball 55A out of the opening 82A in the lower ball-receiving plug 82, down the non-obstructed ball insertion opening 32, out of the outlet 33 and into the well bore 25. Note that the end surface 85A of the push rod 85 remains engaged with the lower ball-receiving plug 82 as the rod 38B of the inserter piston 38 is extended so as to maintain the vertical position of the lower ball-receiving plug 82 and keep the spring 84 compressed. Figure 20 depicts the ball insertion device 103 after the ball inserter piston 38 has been returned to its fully retracted position.

Figure 21 depicts the ball insertion device 103 after the push rod 85 has been retracted to its fully retracted position. The retraction of the push rod 85 allows the spring 84 to expand and force the lower ball-receiving plug 82 back into it fully seated position within the ball-receiving opening 34 where the seals 88, 90 sealingly engage the inner surface of the ball-receiving opening 34. At this point, the lower ball-receiving plug seal integrity line 92 may be accessed to insure that the seals 88, 90 are performing their intended sealing function. The process may be repeated as additional frac balls 55 are introduced into the well bore 25, i.e., upper plug 80 may be withdrawn from its seated position in the ball receiving opening 34, the chain of ball carriers

64 may be advanced such that the frac ball 55B in the ball carrier 64C may be inserted into the well bore using the system disclosed herein.

The particular embodiments disclosed above are illustrative only, as the disclosed subject matter may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. For example, the process steps set forth above may be performed in a different order. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modi- fied and all such variations are considered within the scope and spirit of the claimed subject matter. Note that the use of terms, such as "first," "second," "third" or "fourth" to describe various processes or structures in this specification and in the attached claims is only used as a shorthand reference to such steps/structures and does not necessarily imply that such steps/structures are performed/formed in that ordered sequence. Of course, depending upon the exact claim language, an ordered sequence of such processes may or may not be required. Accordingly, the protection sought herein is as set forth in the claims below.