A tubing pressure operated sliding sleeve is used in cementing a tubular string. The sleeve is configured to hold closed as pressure builds to a predetermined value. When pressure is further raised a rupture disc blows and provides access to an integral piston disposed outside the sleeve. The back side of the piston is exposed to a low pressure or atmospheric chamber located between upper and lower seals. The sleeve thickness near the chamber can be made relatively thick to avoid flexing or bending under differential pressure because the net force to shift the sleeve is from differential pressure on the piston rather than the piston areas created by the upper and lower seals.
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1. A valve for subterranean use, comprising:
a housing having a passage therethrough and a port in a wall thereof;
a sleeve having a flow path therethrough movably mounted in said passage of said housing between a first position where said port is closed and a second position where said port is at least in part open;
a piston associated with said sleeve for moving said sleeve, said piston selectively isolated from passage pressure until a predetermined pressure is reached.
21. A valve for subterranean use, comprising:
a housing having a passage therethrough and a port in a wall thereof;
a sleeve having a flow path therethrough movably mounted in said housing between a first position where said port is closed and a second position where said port is at least in part open;
a piston associated with said sleeve for moving said sleeve, said piston selectively isolated from passage pressure until a predetermined pressure is reached;
said sleeve is retained with a selectively defeated retainer until such time as said piston is no longer isolated from passage pressure.
0. 34. A method of temporarily isolating the inside of a valve from an open-hole well comprising:
running a valve connected to casing into an open-hole well, the valve including a housing having a passage therethrough and a port in a wall of the housing, and a sleeve positioned within the passage and movable upon exposure to a predetermined passage pressure from an initial closed position that covers the port to an open position that uncovers at least a portion of the port;
exposing the sleeve to the predetermined passage pressure; and
moving the sleeve from the initial closed position to the open position.
19. A valve for subterranean use, comprising:
a housing having a passage therethrough and a port in a wall thereof;
a sleeve having a flow path therethrough movably mounted in said housing between a first position where said port is closed and a second position where said port is at least in part open;
a piston associated with said sleeve for moving said sleeve, said piston selectively isolated from passage pressure until a predetermined pressure is reached;
said piston has a first side that is selectively exposed to passage pressure and a second side opposite said first side exposed to a closed chamber in said housing;
said first side of said piston is exposed to a second chamber in said housing.
0. 23. A valve for use in a cementable open-hole well comprising:
a housing having a passage therethrough and a port in a wall thereof for providing access from an interior of said housing to an exterior of the housing;
a sleeve having a longitudinal flow path therethrough movably mounted in said passage of said housing, the sleeve being movable from an initial closed position to an open position;
wherein when said sleeve is in said closed position the interior of said housing is isolated from the exterior of said housing and wherein when said sleeve is in said open position the port provides access from the interior of the housing to the exterior of the housing; and
a piston associated with said sleeve for moving said sleeve from the initial closed position to the open position, said piston selectively isolated from pressure within the passage until a predetermined pressure within the passage is reached.
4. The valve of
said piston is selectively isolated from passage pressure by a pressure responsive barrier that opens.
5. The valve of
said pressure responsive barrier comprises at least one rupture disc.
6. The valve of
said piston has a first side that is selectively exposed to passage pressure and a second side opposite said first side exposed to a closed chamber in said housing.
8. The valve of
said sleeve is configured to respond to passage pressure below said predetermined level by being urged toward said first position.
9. The valve of
said closed chamber has an initial pressure of atmospheric or a predetermined value lower than an anticipated hydrostatic pressure in said passage.
10. The valve of
movement of said sleeve toward said second position reduces the volume of said closed chamber.
11. The valve of
said sleeve is retained with at least one shear pin until such time as said piston is no longer isolated from passage pressure.
12. The valve of
said piston has a first side that is selectively exposed to passage pressure and a second side opposite said first side exposed to a closed chamber in said housing.
14. The valve of
said closed chamber has an initial pressure of atmospheric or a predetermined value lower than an anticipated hydrostatic pressure in said passage.
15. The valve of
movement of said sleeve toward said second position reduces the volume of said closed chamber.
16. The valve of
said sleeve is configured to respond to passage pressure below said predetermined level by being urged toward said first position.
17. The valve of
said sleeve has piston areas adjacent opposed ends defined by seals against said housing wall that are of unequal diameters.
18. The valve of
said selective isolation is accomplished by a barrier that is undermined in response to a predetermined substance, energy field, temperature or other subterranean condition.
20. The valve of
said second chamber is defined in part by said sleeve and decreases in volume with movement of said sleeve toward said second position.
0. 24. The valve of claim 23, wherein said piston is integral to said sleeve.
0. 25. The valve of claim 23, wherein said piston is selectively isolated from passage pressure by a pressure responsive barrier that responds to the predetermined pressure by allowing passage pressure to access said piston.
0. 26. The valve of claim 25, wherein said pressure responsive barrier comprises at least one rupture disc.
0. 27. The valve of claim 26, where the predetermined pressure within the passage bursts the rupture disc.
0. 28. The valve of claim 27, wherein said piston has a first side that is selectively exposed to passage pressure and a second side opposite said first side exposed to a closed chamber in said housing.
0. 29. The valve of claim 28, wherein said chamber has an initial pressure of atmospheric or a predetermined value lower than an anticipated hydrostatic pressure in said passage.
0. 30. The valve of claim 28, wherein movement of the sleeve to said open position reduces a volume of the closed chamber.
0. 31. The valve of claim 23, wherein pressure within the passage below the predetermined pressure urges the sleeve toward the closed position.
0. 32. The valve of claim 23, wherein the piston is isolated from a pressure exterior of the housing.
0. 33. The valve of claim 23, wherein cement may be pumped from the passage of the housing when the sleeve is in said closed position.
0. 35. The method of claim 34, wherein the step of exposing the sleeve to the predetermined pressure further comprises actuating a pressure responsive barrier in the passage by exposing the pressure responsive barrier to the predetermined pressure.
0. 36. The method of claim 35, wherein actuating the pressure responsive barrier comprises bursting the pressure responsive barrier to expose the sleeve to the predetermined pressure.
0. 37. The method of claim 36, wherein bursting the pressure responsive barrier exposes a first side of a piston to the predetermined pressure and a second side of the piston being exposed to a closed chamber in the housing, the piston being operatively connected to the sleeve.
0. 38. The method of claim 37, moving the piston to reduce a volume of the closed chamber.
0. 39. The method of claim 38, wherein the closed chamber has an initial pressure that is less than the predetermined pressure.
0. 40. The method of claim 39, wherein the piston is integral to the sleeve.
0. 41. The method of claim 34, wherein the pressure within the passage urges the sleeve to the initial position until the pressure reaches the predetermined pressure.
0. 42. The method of claim 41, further comprising shearing a shearable device prior to moving the sleeve from the initial position to the open position.
0. 43. The method of claim 34, wherein the step of exposing the sleeve to the predetermined pressure further comprises actuating a chemically responsive barrier in the passage by exposing the chemically responsive barrier to a predetermined substance, energy field, or temperature.
0. 44. The method of claim 34, wherein the sleeve is exposed to the predetermined pressure after a cementation process.
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The field of the invention is a pressure actuated sleeve used in a cementing assembly that is responsive to tubing pressure to open a port and more particularly a sleeve that is associated with a piston where the piston is not referenced to annulus pressure when actuated by selective communication of tubing pressure to one side with the opposed side referenced to a low pressure chamber within the housing.
Prior sleeves that have been deployed in cementing service have been based on the concept of providing opposed piston areas exposed to tubing pressure that are of different dimensions so that raising the tubing pressure will create a sufficient net force to in theory overcome seal friction and move the sleeve to the open position. One such design is Halliburton Initiator Sliding Sleeve that has a larger upper seal diameter than a lower seal. Raising tubing pressure creates a net differential force and the piston is allowed to move because there is an atmospheric chamber between the upper and lower seals. The problem is that to get the lower seal to be smaller than the upper seal to create the desired net force in the needed direction, the wall of the sleeve adjacent the lower seal and the atmospheric chamber has to be reduced so that the sleeve can shift while the volume of the atmospheric chamber is reduced.
The wall of the sleeve in the area of the atmospheric chamber sees substantial differential pressure and can flex or bend. When that happens the sleeve gets stuck and the desired port opening in the housing fails to occur.
Apart from these designs there are sleeves that respond to tubing pressure with an associated piston that is open on one side to tubing pressure and on the other side to annulus pressure. Such a design is illustrated in US Publication 2011/0100643. This design cannot be used in cementing applications as the filling up of the annulus with cement can block access to annulus pressure. Furthermore, there is a leak path potential from the tubing to the annulus through a piston seal leak.
Various pressure operated sleeves for downhole use are shown in U.S. Pat. Nos. and Publications: 7,703,510; 3,662,834; 4,330,039; 6,659,186; 6,550,541; 5,355,959; 4,718,494; 7,640,988; 6,386,289; US 2010/0236781 A1; U.S. Pat. Nos. 5,649,597; 5,044,444; 5,810,087; 5,950,733; 5,954,135; 6,286,594; 4,434,854 and 3,189,044.
What is needed and provided by the present invention is an actuation technique for a sliding sleeve to open a port that responds to tubing pressure but addresses the flexing or bending problem associated with prior designs so that reliable movement of the sleeve is obtained. In the preferred embodiment the application of pressure to a predetermined level actually holds the sleeve closed because the piston area on the sleeve bottom at 31 is greater than the piston area at the top of the sleeve at 32. Doing this allows the sleeve wall near the atmospheric or low pressure chamber to be strong enough to resist bending or buckling under a predetermined differential pressure. When the pressure is built up access is provided to a piston on the sleeve that is referenced to a low pressure or atmospheric chamber. This can be done with breaking a rupture disc. The sleeve can then move to open the port or ports for annulus access so that tools can be pumped down with flow without having to perforate the casing which can save a run in the hole with a perforating gun. Those skilled in the art will better appreciate more aspects of the invention from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined by the appended claims.
A tubing pressure operated sliding sleeve is used in cementing a tubular string. The sleeve is configured to hold closed as pressure builds to a predetermined value. When pressure is further raised a rupture disc blows and provides access to an integral piston disposed outside the sleeve. The back side of the piston is exposed to a low pressure or atmospheric chamber located between upper and lower seals. The sleeve thickness near the chamber can be made relatively thick to avoid flexing or bending under differential pressure because the net force to shift the sleeve is from differential pressure on the piston rather than the piston areas created by the upper and lower seals.
Referring to
upper body tubular connection 1;
upper ported housing 2;
inner shifting sleeve 3;
port isolation seals 4;
upper internal polished bore 5;
fluid communication ports 6;
sleeve shear screw shoulder 7;
shear screws 8;
upper internal bore piston seals 9;
intermediate internal polished bore 10;
upper pressure testing port 11;
upper atmospheric chamber 12;
burst disk load nut 13;
burst disk load ring 14;
burst disk or chemically responsive barrier 15;
intermediate internal bore piston seals and piston 16;
sleeve lock ring retention groove 17;
lower internal polished bore 18;
lower atmospheric chamber 19;
sleeve lock ring retainer 20;
sleeve lock ring 21;
body seals 22;
body connection 23;
body set screws 24;
lower sleeve polished bore 25;
lower pressure testing port 26;
lower external rod piston seals 27;
lower body 28; and
lower body tubular connection 29.
The valve is run in open-hole cementable completions just above the float equipment. The valve is connected to the casing; through the upper body tubular connection (1) at the top and the lower body tubular connection (29) at the bottom. The structural valve body is made-up of an upper ported housing (2) and lower body (28). Pressure integrity of the valve is maintained with the body seals (22). The body set screws (24) keep the body connection threads (23) from backing out during installation. Between the upper ported housing (2) and the lower body (28) is captured an inner shifting sleeve (3). The inner shifting sleeve (3) has several diameters that create piston areas that generate shifting forces to open the valve. The port isolation seals (4) located on the upper end of the inner shifting sleeve (3) and the upper internal bore piston seals (9) below the fluid communication ports (6) both act to isolate the inside of the valve during and after cementation. The larger intermediate internal bore piston seals (16) are used to drive down the inner shifting sleeve (3) along the lower internal polished bore (18) within the upper ported housing (2), once the burst disk (15) is ruptured. Both sets of seals operate within their respective polished bores (5, 10) within the upper ported housing (2). The lower external rod piston seals (27) located within the lower body (28) act to prevent cement from entering the lower atmospheric chamber (19) and wipe the outside diameter of the lower sleeve polished bore (25) during the opening of the valve. The inner shifting sleeve (3) also has a shoulder (7) that shears the shear screws (8) during the opening shift of the inner sleeve (3). An external sleeve lock ring retention groove (17) is located between the internal bore piston seals (16) and the lower sleeve polished bore (25) diameter. This recess will accept the sleeve lock ring (21) that is retained by the lock ring retainer (20) once the valve had fully opened. The sleeve lock ring (21) will prevent the inner shifting sleeve (3) from closing once the valve has fully opened.
Between the upper internal bore piston seals (9) and the intermediate internal bore piston seals (16) is created the upper atmospheric chamber (12) which contains air that can be independently tested through the upper pressure test port (11). Between the intermediate internal bore pistons seals (16) and the lower external rod piston seals (27) is created a lower atmospheric chamber (19) which also contains air that can be independently tested through a lower pressure testing port (26). A burst disk (15) is held into place within a port located on the outside of the inner shifting sleeve (3) by a load ring (14) and a load nut (13). The burst disk load nut (13) is sized to allow significant torque and load to be transferred into the burst disk (15) prior to installation of the inner shifting sleeve (3) within the valve.
The valve is run on casing and cemented into place within the well. After cementation the valve is scraped with wiper dart prior to actuation. Once the cement has set on the outside of the valve, it is ready to be opened with a combination of high hydrostatic and applied pressure. Once the burst pressure is reached, the burst disk (15) opens the upper atmospheric chamber (12) to the applied pressure. This pressure acts on the piston area created by the upper internal bore piston seals (9) and the larger intermediate internal bore piston seals (16) and drives the inner shifting sleeve (3) down compressing the air within the lower atmospheric chamber (19) and opening the fluid communication ports (6) on the upper ported housing (2). Once the inner shifting sleeve (3) is completely shifted and in contact with the upward facing shoulder on the lock ring retainer (20), the sleeve lock ring (21) falls into the sleeve lock retention groove (17) on the inner shifting sleeve (3) preventing the valve from subsequently closing.
Those skilled in the art will appreciate that the use of the rupture disc for piston access is simply the preferred way and generally more accurate than relying exclusively on shearing a shear pin. A pressure regulation valve can also be used for such selective access as well as a chemically responsive barrier that goes away in the presence of a predetermined substance or energy field, temperature downhole or other well condition for example, schematically illustrated by arrow 30, to move the sleeve. Chamber (12), once the rupture disc burst is under tubing pressure so wall flexure at that location is minimized. Even before the rupture disc breaks the size of chamber (12) is sufficiently small to avoid sleeve wall flexing in that region. The use of a large boss to support the seal (16) also strengthens the sleeve (3) immediately above the chamber (19), thus at least reducing flexing or bending that could put sleeve (3) in a bind before it fully shifted. The slightly larger dimension of seal (27) than seal (4) that holds the sleeve (3) closed initially also allows a greater wall thickness for sleeve (3) near the chamber (19) to further at least reducing flexing or bending to allow the sleeve (3) to fully shift without getting into a bind.
The piston (16) can be integral to the sleeve (3) or a separate structure. Chamber (19) has an initial pressure of atmospheric or a predetermined value less than the anticipated hydrostatic pressure within sleeve (3). The volume of chamber (19) decreases and its internal pressure rises as sleeve (3) moves to open port (6).
The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below.
Johnson, Charles C., Avant, Marcus A., Kellner, Justin C., Kirkpatrick, Charles T., Jason, Mailand C.
| Patent | Priority | Assignee | Title |
| 10066467, | Mar 12 2015 | NCS MULTISTAGE INC | Electrically actuated downhole flow control apparatus |
| 10294755, | Apr 27 2012 | Tejas Research & Engineering, LLC | Dual barrier injection valve with a variable orifice |
| 10378312, | Apr 27 2012 | Tejas Research & Engineering, LLC | Tubing retrievable injection valve assembly |
| 10465478, | Aug 25 2017 | Tercel Oilfield Products USA LLC | Toe valve |
| 10704361, | Apr 27 2012 | Tejas Research & Engineering, LLC | Method and apparatus for injecting fluid into spaced injection zones in an oil/gas well |
| 10808509, | Mar 12 2015 | NCS Multistage Inc. | Electrically actuated downhole flow control apparatus |
| 11702904, | Sep 19 2022 | Lonestar Completion Tools, LLC | Toe valve having integral valve body sub and sleeve |
| 9752412, | Apr 08 2015 | Superior Energy Services, LLC | Multi-pressure toe valve |
| Patent | Priority | Assignee | Title |
| 3054415, | |||
| 3189044, | |||
| 3442328, | |||
| 3662834, | |||
| 3831680, | |||
| 3930540, | Sep 11 1972 | Halliburton Company | Wellbore circulating valve |
| 3964544, | Jun 20 1975 | Halliburton Company | Pressure operated isolation valve for use in a well testing and treating apparatus, and its method of operation |
| 3986554, | May 21 1975 | Schlumberger Technology Corporation | Pressure controlled reversing valve |
| 4109724, | Oct 27 1977 | Halliburton Company | Oil well testing valve with liquid spring |
| 4257484, | Mar 10 1980 | Pressure differential circulating valve | |
| 4284152, | Nov 01 1979 | Halliburton Company | Pump in core breaker carrier |
| 4330039, | Jul 07 1980 | Halliburton Company | Pressure actuated vent assembly for slanted wellbores |
| 4403659, | Apr 13 1981 | Schlumberger Technology Corporation | Pressure controlled reversing valve |
| 4427070, | Mar 29 1982 | O'Brien-Goins Engineering, Inc. | Circulating and pressure equalizing sub |
| 443454, | |||
| 4434854, | Jul 07 1980 | Halliburton Company | Pressure actuated vent assembly for slanted wellbores |
| 4515217, | Dec 27 1983 | Baker Oil Tools, Inc. | Perforating gun pressure activated sliding sleeve |
| 4691779, | Jan 17 1986 | HALLIBURTON COMPANY, A CORP OF DELAWARE | Hydrostatic referenced safety-circulating valve |
| 4718494, | Dec 30 1985 | Schlumberger Technology Corporation; SCHLUBMERGER TECHNOLOGY CORPORATION, A CORP OF TEXAS | Methods and apparatus for selectively controlling fluid communication between a pipe string and a well bore annulus |
| 4907655, | Apr 06 1988 | Schlumberger Technology Corporation | Pressure-controlled well tester operated by one or more selected actuating pressures |
| 4979569, | Jul 06 1989 | SCHLUMBERGER TECHNOLOGY CORPORATION, A CORP OF TX | Dual action valve including at least two pressure responsive members |
| 4991654, | Nov 08 1989 | HALLIBURTON COMPANY, A CORP OF DE | Casing valve |
| 5044444, | Apr 28 1989 | Baker Hughes Incorporated | Method and apparatus for chemical treatment of subterranean well bores |
| 5188183, | May 03 1991 | BAKER HUGHES INCORPORATED A CORP OF DELAWARE | Method and apparatus for controlling the flow of well bore fluids |
| 5325917, | Oct 21 1991 | Halliburton Company | Short stroke casing valve with positioning and jetting tools therefor |
| 5355959, | Sep 22 1992 | Halliburton Company | Differential pressure operated circulating and deflation valve |
| 5511617, | Aug 04 1994 | Marathon Oil Company | Apparatus and method for temporarily plugging a tubular |
| 5649597, | Jul 14 1995 | Halliburton Company | Differential pressure test/bypass valve and method for using the same |
| 5676208, | Jan 11 1996 | HALLIBURTON COMPANY, LEGAL INTELL PROPERTY DEPT | Apparatus and methods of preventing screen collapse in gravel packing operations |
| 5765641, | Nov 22 1995 | Halliburton Company | Bidirectional disappearing plug |
| 5810087, | May 10 1996 | Schlumberger Technology Corporation | Formation isolation valve adapted for building a tool string of any desired length prior to lowering the tool string downhole for performing a wellbore operation |
| 5819853, | Aug 08 1995 | Schlumberger Technology Corporation | Rupture disc operated valves for use in drill stem testing |
| 5950733, | May 10 1996 | Schlumberger Technology Corporation | Formation isolation valve |
| 5954135, | Jan 17 1997 | Halliburton Energy Services, Inc | Method and apparatus for establishing fluid communication within a subterranean well |
| 6109354, | Apr 18 1996 | Halliburton Energy Services, Inc. | Circulating valve responsive to fluid flow rate therethrough and associated methods of servicing a well |
| 6148919, | Apr 24 1998 | Halliburton Energy Services, Inc | Apparatus having a releasable lock |
| 6186227, | Apr 21 1999 | Schlumberger Technology Corporation | Packer |
| 6220357, | Jul 17 1997 | Specialised Petroleum Services Group Limited | Downhole flow control tool |
| 6230811, | Jan 27 1999 | Halliburton Energy Services, Inc | Internal pressure operated circulating valve with annulus pressure operated safety mandrel |
| 6286594, | Oct 09 1997 | Baker Hughes Incorporated | Downhole valve |
| 6293346, | Sep 21 1998 | Schlumberger Technology Corporation | Method and apparatus for relieving pressure |
| 6308783, | Apr 26 1996 | Schlumberger Technology Corporation | Wellbore flow control device |
| 6386289, | Feb 12 1998 | Schlumberger Technology Corporation | Reclosable circulating valve for well completion systems |
| 6397949, | Aug 21 1998 | SUPERIOR ENERGY SERVICES, L L C | Method and apparatus for production using a pressure actuated circulating valve |
| 6550541, | May 12 2000 | Schlumberger Technology Corporation | Valve assembly |
| 6604582, | Jun 05 2000 | Schlumberger Technology Corporation | Downhole fluid pressure signal generation and transmission |
| 6659183, | Feb 22 2001 | ABB Vetco Gray Inc.; ABB VETCO GRAY INC | Cuttings injection target plate |
| 6659186, | May 12 2000 | Schlumberger Technology Corporation | Valve assembly |
| 6684950, | Mar 01 2001 | Schlumberger Technology Corporation | System for pressure testing tubing |
| 6722439, | Mar 26 2002 | Baker Hughes Incorporated | Multi-positioned sliding sleeve valve |
| 6834726, | May 29 2002 | Wells Fargo Bank, National Association | Method and apparatus to reduce downhole surge pressure using hydrostatic valve |
| 6907936, | Nov 19 2001 | PACKERS PLUS ENERGY SERVICES INC | Method and apparatus for wellbore fluid treatment |
| 6945331, | Jul 31 2002 | Schlumberger Technology Corporation | Multiple interventionless actuated downhole valve and method |
| 6948561, | Jul 12 2002 | Baker Hughes Incorporated | Indexing apparatus |
| 7063152, | Oct 01 2003 | Baker Hughes Incorporated | Model HCCV hydrostatic closed circulation valve |
| 7464758, | Oct 02 2002 | Baker Hughes Incorporated | Model HCCV hydrostatic closed circulation valve |
| 7562713, | Feb 21 2006 | Schlumberger Technology Corporation | Downhole actuation tools |
| 7640988, | Mar 18 2005 | EXXON MOBIL UPSTREAM RESEARCH COMPANY | Hydraulically controlled burst disk subs and methods for their use |
| 7703510, | Aug 27 2007 | BAKER HUGHES HOLDINGS LLC | Interventionless multi-position frac tool |
| 7762324, | Dec 04 2007 | BAKER HUGHES HOLDINGS LLC | Bypass crossover sub selector for multi-zone fracturing processes |
| 7841412, | Feb 21 2007 | Baker Hughes Incorporated | Multi-purpose pressure operated downhole valve |
| 7845416, | Nov 11 2005 | Baker Hughes Incorporated | Hydraulic sleeve valve with position indication, alignment, and bypass |
| 7909095, | Oct 07 2008 | Halliburton Energy Services, Inc | Valve device and associated methods of selectively communicating between an interior and an exterior of a tubular string |
| 7913770, | Jun 30 2008 | Baker Hughes Incorporated | Controlled pressure equalization of atmospheric chambers |
| 8171994, | Aug 16 2007 | Baker Hughes Incorporated | Multi-position valve for fracturing and sand control and associated completion methods |
| 8261761, | May 07 2009 | BAKER HUGHES OILFIELD OPERATIONS LLC | Selectively movable seat arrangement and method |
| 8276670, | Apr 27 2009 | Schlumberger Technology Corporation | Downhole dissolvable plug |
| 8789600, | Aug 24 2010 | BAKER HUGHES OILFIELD OPERATIONS LLC | Fracing system and method |
| 9303501, | Nov 19 2001 | Packers Plus Energy Services Inc. | Method and apparatus for wellbore fluid treatment |
| 20040118566, | |||
| 20080066923, | |||
| 20090065194, | |||
| 20090065212, | |||
| 20100236781, | |||
| 20110056679, | |||
| 20110100643, | |||
| 20110114324, | |||
| 20110259582, | |||
| 20110278017, | |||
| 20120006553, | |||
| 20120048559, | |||
| 20120085548, | |||
| 20120186803, | |||
| 20120211242, | |||
| 20120267119, | |||
| 20120285702, | |||
| 20120305265, | |||
| 20130043041, | |||
| WO2012115868, | |||
| WO2012145735, |
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