A SUBTERRANEAN FORMATION

FIELD OF THE INVENTION

[0001] This disclosure relates to a system for the continuous circulation of produced fluids.

BACKGROUND OF THE DISCLOSURE

[0002] A typical oil well produces not only oil, but also gas and water, often in significant quantities. The fluids often transport solids, such as sand, as well as other fluids and gases, from the reservoir into the production tubing and casing, and up the production tubing to the surface. Equipment on the surface may be used to separate these production components. The oil is recovered; the gas, depending on composition, may be filtered, treated and piped to a collection facility or flared off; the water may be re-injected into another formation or, in the case of offshore production platforms, treated to prevent environmental contamination and then discharged overboard; and the solids are separated and disposed of.

[0003] In the oil and gas industry, it is common to introduce fluids into oil or gas wells. Such fluids, which are frequently used during both drilling and production phases, include, but are not limited to, acids, surfactants, corrosion inhibitors and/or other additives or chemicals aimed at improving the drilling process and/or the producing characteristics of a well. Frequently, such fluids can be pumped down a well from the earth's surface and comingled with other fluids in such well. However, in other situations, it is advantageous to introduce such fluids at or near the bottom of a well; that is, the subject fluids are kept isolated from other fluids until they are released into the wellbore environment at a desired downhole location.

[0004] As existing oil fields mature, it is becoming increasingly common to inject beneficial chemicals and/or other additives into older oil and gas wells. Hydrocarbon production often decreases in such mature wells while associated salt water production increases. In many cases, this phenomenon is coupled with a decline in reservoir pressure required to lift produced fluids (including the heavier saltwater) from the bottom of a well to the surface. As water production increases, and reservoir pressure decreases, hydrocarbon production is frequently "choked off and greatly diminished. As a result, it is often desirable to increase the overall production rate from such wells in order to improve recovery of hydrocarbons from the well stream.

[0005] Water pumps located downhole are utilized for extracting or pumping water from subterranean wells are known. Such water pumps may be powered, at least in part, by a hydraulic pump located on the surface of the Earth. Hydraulic oil lines permit hydraulic fluid to flow to the water pump to drive a piston within the pump.

[0006] Significant solids can be produced with produced fluid being pumped from the wellbore to the surface. If the pump is shutdown for some period of time, when the fluid level in the pump reaches the pump inlet, the solids can settle to the bottom of the liquid production conduit, resulting in packing off and blockage of further production. Additionally, a significant amount of gas can be pulled into the production conduit, if the pump continues to operate once the liquid level is below the pump inlet. As this gas expands and it rises in the production conduit, much of the liquid can be displaced. This can result in a significant reduction in the hydrostatic pressure required to effectively cycle a hydraulic pump.

[0007] Without continuous flow, solids could fall back downhole, bridge the pump outlet, pack off and block flow when pumping resumes. Therefore, a system and method is needed to continuously circulate fluid into the wellbore.

BRIEF SUMMARY OF THE DISCLOSURE

[0008] In an embodiment, a system for the continuous circulation of produced fluids from a subterranean formation includes: a hydraulic pump positioned at a surface of the subterranean formation; a downhole pump positioned within the subterranean formation; a circulating pump positioned at a surface of the subterranean formation; a downhole hydraulic line operatively connected between the hydraulic pump and the downhole pump, wherein the downhole hydraulic line supplies a hydraulic fluid from the hydraulic pump to the downhole pump and from the downhole pump back to the hydraulic pump; a downhole removal line operatively connected between the downhole pump and the surface, wherein the downhole removal line removes produced fluids along why any entrained gas and solids from the subterranean formation via the downhole pump and delivers the produced fluid to a surface separator; and a downhole supply line operatively connected between the circulating pump and the downhole pump, wherein the downhole delivery line delivers produced fluids from the surface via the circulating pump to the downhole pump.

[0009] In another embodiment, a system for continuous circulation of produced fluids from a subterranean formation includes: a hydraulic pump positioned at a surface of the subterranean formation; a downhole pump positioned within the subterranean formation; a circulating pump positioned at a surface of the subterranean formation; a transfer chamber positioned a the surface of the subterranean formation, wherein the transfer chamber includes a floating transfer piston which separates the produced fluids and a hydraulic fluid; a downhole hydraulic line operatively connected between the hydraulic pump and the downhole pump, wherein the downhole hydraulic line supplies a hydraulic fluid from the hydraulic pump to the downhole pump; a downhole removal line operatively connected between the downhole pump and the surface, wherein the downhole removal line removes produced fluids along wtih any entrained gas and solids from the subterranean formation via the downhole pump and delivers the produced fluid to the surface and from the downhole pump back to the hydraulic pump; a downhole supply line operatively connected between the high pressure pump and the downhole pump, wherein the downhole supply line removes produced fluids from the surface via the circulating pump and delivers produced fluids to the subterranean formation via the downhole pump; and a transfer chamber line connected from the transfer chamber to the hydraulic pump.

[0010] In a further embodiment, a system for continuous circulation of produced fluids from a subterranean formation includes: a hydraulic pump positioned at a surface of the subterranean formation; a downhole pump positioned within the subterranean formation; a circulating pump positioned at a surface of the subterranean formation; a transfer chamber positioned a the surface of the subterranean formation, wherein the transfer chamber includes a floating transfer piston which separates the produced fluids and a hydraulic fluid; a downhole hydraulic line operatively connected between the hydraulic pump and the downhole pump, wherein the downhole hydraulic line supplies a hydraulic fluid from the hydraulic pump to the downhole pump; a downhole removal line operatively connected between the downhole pump and a separator at the surface, wherein the downhole removal line removes produced fluids along with any entrained gas and solids from the subterranean formation via the downhole pump and delivers them to the separator; a downhole supply line operatively connected between the high pressure pump and the downhole pump, wherein the downhole supply line removes produced fluids from the surface via the circulating pump and delivers produced fluids to the subterranean formation via the downhole pump; and a transfer chamber line connected from the transfer chamber to the separator. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] A more complete understanding of the present disclosure and benefits thereof may be acquired by referring to the follow description taken in conjunction with the accompanying drawings in which:

[0012] FIG. 1 is a schematic of a water evacuation system of a first embodiment in accordance with the present disclosure.

[0013] FIG. 2 is a schematic of a water evacuation system of a second embodiment in accordance with the present disclosure.

[0014] FIG. 3 is a schematic of a water evacuation system of a third embodiment in accordance with the present disclosure.

DETAILED DESCRIPTION

[0015] Reference will now be made in detail to embodiments of the present invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation of the invention, not as a limitation of the invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used in another embodiment to yield a still further embodiment. Thus, it is intended that the present invention cover such modifications and variations that come within the scope of the appended claims and their equivalents.

[0016] FIG. 1 depicts a water evacuation system 10 for extracting water from a subterranean formation 12 that traverses a distance from the Earth's surface 14 to a water source 16 located below the Earth's surface 14. The system contains at least a downhole pump 18, a hydraulic pump 28 and a circulating pump 48.

[0017] The downhole pump 18 may be located within the water source 16. The downhole pump 18 may be a downhole water pump. The downhole pump may be a single actuated pump. A downhole removal line 22, and a downhole supply line 44 and a downhole hydraulic line 20 may each be connected to the downhole pump 18.

[0018] The downhole removal line 22 may remove produced fluids from the formation via the downhole pump 18 and may deliver the produced fluids to the surface. The downhole removal line 22 may be operatively connected to the downhole pump 18 and to the surface 14. In this embodiment, the downhole pump may be a high pressure water pump.

[0019] The circulating pump 48 may operate continuously and deliver produced fluids from the surface to the downhole pump 18 via the downhole supply line 44 when valve 54 is open. The downhole supply line 44 may be operatively connected to the circulating pump 48 and to the downhole pump 18.

[0020] The downhole hydraulic line 20 may be operatively connected to the hydraulic pump 28 and to the downhole pump 18. The downhole hydraulic line 20 may supply a hydraulic fluid from the hydraulic pump 20.

[0021] The pumping unit 24 may be a hydraulic pumping unit and may employ a multitude of components to enable functioning of the downhole pump 18 and the transfer chamber 40. The pumping unit 24 may employ an electric motor 26, which may drive or turn a hydraulic pump 28 thereby forcing or pumping hydraulic fluid toward a hydraulic control valve 30 located in the downhole hydraulic line 20. A hydraulic pump line 32 may be valveless and leads from the hydraulic pump 28 to either to the transfer chamber 40 or to the downhole hydraulic line 20. When the hydraulic pump line 32 leads from hydraulic pump 28 toward the downhole pump 18, the hydraulic pump line 32 may be a relatively high pressure conduit that supplies pressurized hydraulic fluid for passage or distribution to the downhole pump 18.

[0022] When the downhole hydraulic line 20 is energized by the hydraulic pump 28 with hydraulic pressure sufficient to generate enough force to cause the downhole pump piston 60 to move upwards resulting in removal of water the from water source 16. Further, hydraulic fluid is drawn from the hydraulic fluid tank 46 into the hydraulic pump feed line 27, through the hydraulic pump 28, through the hydraulic pump line 32, through an open downhole hydraulic control valve 30 and into the downhole hydraulic line 20.

[0023] Simultaneously with the downhole hydraulic line valve 30 permitting hydraulic fluid to flow into the downhole hydraulic line 20, a hydraulic drain line valve 98 is closed to prevent hydraulic fluid from flowing into the hydraulic fluid tank 46 through a hydraulic drain line 96. When the transfer chamber fill valve 100 is closed, hydraulic fluid is prevented from flowing into the hydraulic fluid chamber 36 of the transfer chamber 40 during upward motion of the downhole pump piston (not shown), thus preventing the pumped hydraulic fluid and associated hydraulic pressure, intended for the downhole hydraulic line 20, from escaping into the transfer chamber 40 or into the transfer chamber drain line 102. As the downhole pump piston (not shown) strokes upward, water moves toward the Earth's surface 14 through the downhole removal line 22 and into the water chamber 52 of the transfer chamber 40. When a piston (not shown) within the downhole pump 18 reaches its highest possible position, which is the completion of a pumping stroke, a pressure sensor or timer 104 located within the hydraulic pump line 32 senses the hydraulic pressure within the hydraulic pump line 32 and causes a control module (not shown) to actuate the hydraulic control valve 30 to a closed position and to actuate the transfer chamber fill valve 100 to an open position.

[0024] During each upward stroke of the piston (not shown) of the downhole pump 18, the floating transfer piston 42 moves within the transfer chamber 40 causing a progressive increase in the volume of the water chamber 52 and a corresponding progressive decrease in the volume of the hydraulic fluid chamber 36. The floating transfer piston 42 maintains contact against the cylindrical interior wall of the transfer chamber 40 to maintain a leak-proof seal between the water chamber 52 and the hydraulic fluid chamber 36 so that water and hydraulic fluid are always separated and are prevented from mixing. Despite such a leak-proof seal, the floating transfer piston 42 may move when subjected to a force. Thus, each upward movement of the piston (not shown) of the downhole pump 18 causes the floating transfer piston 42 to move so as to increase the volume of the water chamber 52 with the water valve 54 closed. While the floating transfer piston 42 actuates due to the filling of the water chamber 52 with water, a volume of hydraulic fluid equal to a volume of hydraulic fluid displaced by movement of the floating transfer piston 42 flows out of hydraulic fluid chamber 36 and into the transfer chamber hydraulic oil line 38. When the transfer chamber drain line valve 106 is open, the transfer chamber fill valve 100 is closed. The transfer chamber fill valve 100 is located in a fluid path between the hydraulic pump 28 and the hydraulic fluid chamber 36 of the transfer chamber 40 and is normally closed when hydraulic fluid is flowing into the hydraulic fluid tank 46 during movement of the floating transfer piston 42 due to water filling the water chamber 52 of the transfer chamber 40.

[0025] Because hydraulic pump 28 operates continuously and thereby continuously draws fluid from hydraulic tank 46, upon downhole pump piston (not shown) reaching its upper stroke limit within downhole pump 18 pressure within downhole hydraulic line 20 and hydraulic pump line 32 will increase, which pressure sensor 104 will detect. Upon pressure sensor 104 sensing an increase in hydraulic pressure at or above a predetermined or threshold pressure within hydraulic pump line 32, which may exhibit the same pressure as downhole hydraulic line 20, a control module (not shown) in communication with sensor 104 causes a series of valve changes to occur. With hydraulic pump 28 continuing to operate and pumping hydraulic fluid, transfer chamber drain line valve 106 switches from open to closed, transfer chamber fill valve 100 switches from closed to open, hydraulic drain line valve 98 switches from closed to open, water valve 54 switches from open to closed, and hydraulic control valve 30 switches from open to closed. Thus, upon valves 30, 54, 98, 100, and 106 changing positions as noted above, hydraulic fluid exiting hydraulic pump 28 flows only through transfer chamber fill valve 100, through transfer chamber hydraulic oil line 38 and into hydraulic fluid chamber 36. With hydraulic fluid flowing into hydraulic fluid chamber 36 and thus increasing pressure within hydraulic fluid chamber 36, floating transfer piston 42 begins to move within transfer chamber 40 thereby increasing a volume of hydraulic fluid chamber 36 and decreasing a volume of water chamber 52. With water valve 54 closed, water pressure builds within removal line 22 as hydraulic pressure in hydraulic fluid chamber 36 increases and floating transfer piston 42 moving to evacuate water from water chamber 52. Increasing water pressure in water chamber 52 and downhole removal line 22 forces downhole pump piston (not shown) downward in accordance with a direction of arrow 67, which is also a direction opposite that of a water-pumping stroke as depicted with direction of arrow 66.

[0026] Turning now to FIG. 2, a detailed description of another embodiment of the present disclosure will be presented. FIG. 2 depicts an evacuation system 150 for extracting water from a subterranean formation 12, such as an oil and gas well, or other well, that traverses a distance from the Earth's surface 14 to a water source 16 located below Earth's surface 14. As can be seen in a comparison of FIGS. 1 and FIG. 2, FIG. 2 shares many of the same components as the apparatus depicted in FIG. 1. One difference, however, is in a backflow mechanism 152, which includes water repository 154, surface pump 156, downhole pump draw pipe 158, downhole pump supply line 160, tank filling tube 162 and dump valve 164.

[0027] Evacuation system 150 may have subterranean downhole pump 18 located within water source 16. Downhole hydraulic line 20 and downhole removal line 22 may each be connected to the subterranean downhole pump 18. Downhole removal line 22 may also be part of a backflow mechanism 152 of pumping unit 166. Pumping unit 166 may be a hydraulic pumping unit and may employ a multitude of components to enable functioning of subterranean downhole pump 18 and backflow mechanism 152, including surface downhole pump 156. Pumping unit 166 may employ an electric motor 26, which may drive or turn hydraulic pump 28 thereby forcing or pumping hydraulic fluid into downhole hydraulic line 20 and into downhole pump 18 to energize or drive downhole pump 18. Downhole pump 18 may utilize one downhole hydraulic line 20 and one downhole removal line 22 for operation. Downhole hydraulic line 20 and downhole removal line 22 run between or fluidly link downhole pump 18 and components on Earth's surface 14. Details of internal components of downhole pump 18 are explained above in conjunction with FIGS. 2 and 3.

[0028] When downhole hydraulic line 20 is energized by hydraulic pump 28 with hydraulic pressure sufficient to generate enough force to cause downhole pump piston (not shown) to move upwards in a pumping stroke that removes water from water source 16, hydraulic fluid is drawn from hydraulic fluid tank 46, into hydraulic pump feed line 27, through hydraulic pump 28, through hydraulic pump line 32 and into downhole hydraulic line 20 to a rod side of downhole pump piston (not shown) of downhole pump 18. At the same time that hydraulic fluid to flows into downhole hydraulic line 20 during a pumping stroke of downhole pump 18, hydraulic fluid is prevented from flowing into hydraulic fluid tank 46 through hydraulic drain line 96 because hydraulic drain line valve 98 is closed. Upon downhole pump piston (not shown) moving during a pumping stroke, water moves upward toward Earth's surface 14 through downhole removal line 22 and into water tank filling tube 162 with water valve 164 in water tank filling tube 162 open. A pumping stroke of downhole pump piston (not shown) occurs from a lowest possible position of piston (not shown) within piston chamber (not shown) of downhole pump 18, also known as a lowest bottom position, to a highest possible position, also known as a highest top position, of downhole pump piston (not shown) within piston chamber (not shown) of downhole pump 18. When piston (not shown) reaches its highest top position, which is completion of a pumping stroke, a pressure sensor 104 located within hydraulic pump line 32, such as near hydraulic pump 28, senses hydraulic pressure within hydraulic pump line 32 and causes a control module (not shown) to actuate hydraulic drain line valve 98 to an open position.

[0029] Because hydraulic pump 28 continuously operates and draws fluid from hydraulic tank 46, upon downhole pump piston (not shown) reaching its upper stroke limit within downhole pump 18 pressure within downhole hydraulic line 20 and hydraulic pump line 32 will increase, which pressure sensor 104 will detect. Upon pressure sensor 104 indicating an increase in hydraulic pressure at or above a predetermined or threshold pressure within hydraulic pump line 32, a series of valve changes may occur. With hydraulic pump 28 continuing to operate and pump hydraulic fluid, hydraulic drain line valve 98 switches from closed to open, and water valve 164 switches from open to closed. Additionally, surface water pump 156 pumps water into downhole pump supply 160 toward downhole pump 18. Water pressure builds within downhole removal line 22 which forces downhole pump piston (not shown) downward.

[0030] Turning now to FIG. 3, a detailed description of another embodiment of the present disclosure will be presented. FIG. 3 depicts a separator 202 for separating produced fluid and solids from entrained gas. As can be seen in a comparison of FIGS. 1 and FIG. 3, FIG. 3 shares many of the same components as the apparatus depicted in FIG. 1.

[0031] FIG. 3 depicts an evacuation system 200 for extracting water from a subterranean formation 12 that traverses a distance from the Earth's surface 14 to a water source 16 located below the Earth's surface 14. The system contains at least a downhole pump 18, a hydraulic pump 28 and a separator 202.

[0032] The downhole hydraulic line 20 may be operatively connected to the hydraulic pump 28 and to the downhole pump 18. The downhole hydraulic line 20 may supply a hydraulic fluid from the hydraulic pump 28 or from the pumping unit 220 to the downhole pump 18.

[0033] The downhole removal line 22 may remove produced fluids from the formation via the downhole pump 18 and may deliver the produced fluids to the separator 202 through a check valve 206. Separator 202 separates produced fluid and solids. The solids and produced fluids exit the separator via line 205 when dump valve 208 is in an open position. Any gas exits separator 202 via line 207 when dump valve 210 is in an open position. The remaining produced fluid exits the separator 202 through check valve 54 via removal line 203. Removal line 203 may be operatively connected to the downhole pump 18 and transfer chamber 40.

[0034] In the above-described embodiments, in closing and opening all valves, and turning on or off all electric pumps, a controller may be employed to automate such processes. Manually causing closing and opening all valves, and turning on or off all electric pumps is also envisioned.

[0035] In an alternate embodiment, the downhole pump can be run on a multi-channel concentric coil tubing string. Hydraulic fluid can be continuously supplied to the downhole pump through via a first channel, filtered production fluid is continuously supplied to the downhole pump via a second channel, produced fluid is removed via a third channel and gas can be removed via a casing string around the exterior of the multi-channel concentric coil tubing string.

[0036] In closing, it should be noted that the discussion of any reference is not an admission that it is prior art to the present invention, especially any reference that may have a publication date after the priority date of this application. At the same time, each and every claim below is hereby incorporated into this detailed description or specification as a additional embodiments of the present invention.

[0037] Although the systems and processes described herein have been described in detail, it should be understood that various changes, substitutions, and alterations can be made without departing from the spirit and scope of the invention as defined by the following claims. Those skilled in the art may be able to study the preferred embodiments and identify other ways to practice the invention that are not exactly as described herein. It is the intent of the inventors that variations and equivalents of the invention are within the scope of the claims while the description, abstract and drawings are not to be used to limit the scope of the invention. The invention is specifically intended to be as broad as the claims below and their equivalents.