Not applicable.
Not applicable.
1. Field of the Invention
The present invention relates to oil and natural gas production. More specifically, the system facilitates the introduction of a fluid under pressure into a wellbore and then sealing the wellbore below a desired depth to prevent egress of the introduced fluids while allowing removal of a portion of a work string from the wellbore.
2. Description of the Related Art
In oil and gas wells, it may be desirable to inject a fluid into the well to enhance production of hydrocarbons. For example, steam, carbon dioxide, water or other fluids may be injected into the well to maintain reservoir pressure or heat the oil to lower its viscosity.
Gas injection is one common approach in enhanced oil recovery, and may use carbon dioxide, natural gas, or nitrogen. When the subject gas is injected, the phase behavior of the mixture of gas and crude causes the desired oil displacement, swelling, or a reduction in the surface tension of the oil with the surrounding formation. Each of these makes the oil easier to produce for the formation.
Enhanced oil recovery using gas injection can present some additional problems. For example, in the event of mechanical problems with equipment already in use with the well (e.g., the pump above the system fails, a tubing leak develops, etc.), the entire tubing string may have to be removed and the operator may have to flow down the well, resulting in significant delay and expense from the well flow down. Moreover, removal of the entire tubing string potentially negates any benefits from the prior fluid introduction, because such introduced fluids would be allowed to egress through the wellbore to the surface when the tubing string is removed.
The present invention addresses the problems such as those identified above by allowing the well operator to remove only a portion of the tubing string and inhibiting the egress of introduced fluids while the portion of the tubing string is removed. For example, in the event of pump failure during injection procedures, an embodiment of the system may be used to pull tubing with the pump attached while isolating flow and pressure from the wellbore below a position. The present invention may be used in either a cased or open wellbore.
An embodiment of the system comprises an annulus sealing device having a flow path therethrough, a first side, and a second side; a latch element positioned at the first side of the annulus sealing device; at least one check valve assembly positioned at the second side of the annulus sealing device, the at least one check valve assembly having an annular seat, a seat-engaging element rotatably movable relative to the annular seat, and a biasing member urging the seat-engaging element toward the annular seat; a rigid elongate member extending at least partially through said latch element and having a first end, a second end, and an outer surface extending between the first end and the second end; and a fluid communication path between the annular seat and through the latch element and at least partially defined by the rigid elongate member.
When used with reference to the figures, unless otherwise specified, the terms “upwell,” “above,” “top,” “upper,” “downwell,” “below,” “bottom,” “lower,” and like terms are used relative to the direction of normal production and/or flow of fluids and/or gas through the tool and wellbore. Thus, normal production results in migration through the wellbore and production string from the downwell to upwell direction without regard to whether the tubing string is disposed in a vertical wellbore, a horizontal wellbore, or some combination of both. Similarly, during the fracing process, fracing fluids and/or gasses move from the surface in the downwell direction to the portion of the tubing string within the formation.
The embodiment comprises a section 26 of a tubing string comprising various downhole tools separated by tubing segments 27. The section 26 includes an annulus sealing device, such as a packer 28, which is set into the sidewall 24 and is in an expanded state to isolate the volume of the wellbore 22 below the packer 28 from the volume above the packer 28. The sealing elements 29 of the packer 28 inhibit pressure and fluids from flowing upwell past the packer 28 through the annulus 30 between the sidewall 24 and the various elements composing the tubing string section 26. The packer 28 has a mandrel defining a flow path, a first, upwell side 32 and a second, downwell side 34. During completion or production, fluid may flow through the mandrel of the packer 28 in either the downwell direction or the upwell direction. In the described embodiment, the packer 28 is a JetSet 1-X double grip mechanical set retrievable packer, available from Peak Completion Technologies, Inc. of Midland, Tex.
A tubing disconnect device 36 is positioned in the tubing string section 26 on the upwell side 32 of the packer 28. The tubing disconnect device 36 is more specifically an on/off tool that includes a latch receiving element 38, a latch element 40, and sealing elements (not shown) to inhibit fluid flow through the device 36 when the latch element 40 is engaged with the latch receiving element 38. The tubing disconnect device 36 of the described embodiment is an on/off tool with the latch receiving element 38 being an overshot and the latch element 40 being a slick joint. More specifically, in the described embodiment, the latch receiving element 38 is a J-2 On Off Tool Overshot, and the latch element 40 is a J-2 On Off Tool Slick Joint, both available from Peak Completion Technologies, Inc. of Midland, Tex. While shown separated by a tubing segment 27, the tubing disconnect device 36 may also be threaded directly to the first side 32 of the packer 28. In alternative embodiments, the tubing disconnect device 36 may be a landing element in combination, and engagable, with a second element having a landing shoulder.
First and second check valve assemblies, such as flapper assemblies 42, 44, are positioned within the tubing string section 26 on the second side 34 of the packer 28. Each check valve assembly 42, 44 is a flapper valve assembly having a flapper plate 46a, 46b rotatable relative to an annular seat 48a, 46b between a closed position and an opened position. In the closed position, the flapper plates 46a, b are sealed against the corresponding seat 48a, 48b to inhibit fluid flow through the assemblies 42, 44 in the upwell direction. Biasing members (not shown), such as torsion springs, urges the flapper plates 46 of each assembly 42, 44 toward the closed position. When in a closed position, fluid flow in the downwell direction exerts a pressure on the flapper plates 46a, 46b, and will overcome the forces of any natural well pressure and the corresponding spring at or above a known threshold pressure. The rotational force exerted by the corresponding spring is a function of the spring characteristics.
A rigid elongate member, such as a flow tube 50, is connected to the latch receiving member 38 of the tubing disconnect device 36, and extends through the latch element 40 to an operating position. The flow tube 50 of the described embodiment is a generally rigid tubular member having a first end 52, a second end 54, and a cylindrical outer surface 76.
The flow tube 50 extends from the latch receiving member 38 through tubing segments 27, the packer 28, and the flapper assemblies 42, 44. The second end 54 of the flow tube 50 is positioned approximately two inches below the lower annular surface 56 of the lower flapper assembly 44, with the flow tube 50 extending through each of the annular seats 48. The first end 52 is connected to the overshot 38 and can receive fluid, such as carbon dioxide, therefrom and direct the received fluid to the second end 54 of the flow tube 50. Because the flow tube 50 is positioned through the flapper assemblies 42, 44, the flapper plates 46a, 46b cannot rotate to a closed position under the force of the associated springs and are in opened states. An annular space 77 extends from the lower the lower annular surface 56 of the lower flapper assembly 44 to the overshot 38, and is partially defined by the cylindrical outer surface 76 and the inner surfaces of the tubing segments 27, packer 28, and first and second check valves 42, 44.
In the described embodiment, the flow tube 50 is steel, but may be made of any material strong enough to mechanically push open the flapper plates 46a, 46b and that is also able to withstand the downhole environment. Alternative materials include, but are not limited to, cheap steel, fiberglass, and premium high strength corrosion-resistant materials.
The embodiment may be installed in the well in at least two ways. First, the embodiment may be run into the wellbore 22 in the state described in FIG. 1—that is, the flow tube 50 is connected to the overshot 38 of the tubing disconnect device 36 and disposed through the packer 28 and the annular seats 48 of the upper and lower flapper assemblies 42, 44. The presence of the flow tube 50 through the seats 48 prevents the flapper plates 46 from completely closing under the force of the springs and sealing against the seats 48. The packer 28 is then set in the desired position within the wellbore 22.
In the event remedial work on part or all of the equipment or well becomes necessary during or after the injection procedure, the well operator may then disconnect the slick joint 40 from the overshot 38. The overshot 38 and flow tube 50 may then be removed from the wellbore 22, leaving the packer 28, flapper assemblies 42, 44, and various tubing segments 27 in the wellbore 22. As the flow tube 50 is removed from the flapper valves 42, 44, the flapper plates 46 seal against the seats 48 to inhibit migration of pressure up the wellbore 22 through the flapper assemblies 42, 44, the flow path of the packer 28, and the slick joint 40. Sealing elements 29 of the packer 28 isolates the wellbore annulus 30 and resists movement urged by the force of wellbore pressures acting on the flapper plates 46 of the flapper assemblies 42, 44. The remedial work can then be performed, and the flow tube 50 reinserted into the wellbore (and the overshot 40 reconnected to the slick joint 38) without having to snub.
In an alternative installation procedure, the packer 28 and flapper assemblies 42, 44 are run into the wellbore 22, and the packer 28 set at the desired depth. The flow tube 50 would be connected to the overshot 38 with any additional desired tools positioned in the tubing string above the overshot 38. The overshot 38 and flow tube 50 would then be run into the wellbore 22. As the second end 54 of the flow tube 50 reaches the flapper assemblies 42, 44, the second end 54 contacts the flapper plates 46 and overcomes the closing force of the spring, causing the flapper plates 46 to open, thus allowing production from or injection into the wellbore 22 through the flow tube 50. The overshot 38 latches on to, and seals with, the slick joint 40 to anchor and seal the system.
An annular seal 72 with sealing elements 62 is nested within the seal body 60 and longitudinally fixed between the seal body 60 and an annular surface 74 of the slotted member 61. The cylindrical outer surface 76 of the flow tube 50 and the cylindrical inner surfaces 78, 80 of the seal body 60 and slotted member 61, respectively, define an annular space 82 that may selectively receive the latch member (not shown).
During use, the overshot 38 may by lowered onto the slick joint (not shown), which will occupy the annular space 82. The slick joint includes a latching member, or nipple, fittable into the J-slots 66 formed in the slotted member 61. By manipulating the pressure and rotation of the overshot 38 relative to the slick joint, the latching member may be selectively moved into or out of the slots 66 to connect or disconnect these two components of the tubing disconnect device.
The flapper assembly 100 further comprises an annular second body 118 having a generally-fixed outer diameter and an inner surface 120 with threads engagable with the threads of the first body 102. The second body 118 has annular first and second end surfaces 122, 124. The annular first surface 122 is positioned adjacent to the intermediate second section 106 of the first body 102. A partially-conical second seat 126 is adjacent to the second end surface 124.
First and second flapper plates 130, 132 are connected and rotatable relative to the second end surfaces 112, 124. The first and second plates 130, 132 have first and second partially-conical surfaces 134, 136, respectively, corresponding to the first and second seats 114, 126.
First and second torsion springs 138, 140 are fixed around first and second spring mounts 142, 144. The springs 138, 140 urge the first and second flapper plates 130, 132, respectively, relative to the first and second bodies 102, 118. First and second partially-conical rubber sealing elements 146, 148 are positioned between the flapper plates 130, 132 and the seats 114, 126.
The rod 250 is a generally elongate rigid member having a first end 252, a second end 254, and a cylindrical outer surface 276. The rod 250 extends from the latch receiving member 38 through tubing segments 27, the packer 28, and the flapper assemblies 42, 44. The second end 254 is positioned approximately two inches below the lower annular surface 256 of the lower flapper assembly 44 and extends through each of the annular seats 48. The first end 252 is connected to the overshot 38. Because the rod 250 is positioned through the flapper assemblies 42, 44, the flapper plates 46a, 46b cannot rotate to a closed position under the force of the associated springs and are in opened states. The outer surface 276 of the rod 250 partially defines an annular space with the inner surfaces of the tubing disconnect device 36, tubing segments 27, packer 28, and first and flapper assemblies 42, 44.
Referring to
The outer surface 76 of the rod 250 and the cylindrical inner surfaces 78, 80 of the seal body 60 and slotted member 61, respectively, define an annular space 282 that may selectively receive the latch member (not shown). A plurality of ports 266 extends between the inner surface 262 and the outer surface 264 and provides a communication path between the overshot 38 and the annular space 282.
The cylindrical outer surface 276 of the rod 250 and the cylindrical inner surfaces 78, 80 of the seal body 60 and slotted member 61, respectively, define an annular space 282 that may selectively receive the latch member (not shown). When used, fluids flowing back to the surface migrate through lower annular surface 56, through the annular space 277 (see
This disclosure describes preferred embodiments in which a specific systems and methods are described. Those skilled in the art will recognize that alternative embodiments of such a system and method can be used in carrying out the present invention. Other aspects and advantages of the present invention may be obtained from a study of this disclosure and the drawings, along with the appended claims.