Not applicable.
1. Field of the Invention
The present invention relates to oil and natural gas production. More specifically, to systems, tools, and methods used in fracturing and/or producing hydrocarbons in one or more stages in a hydrocarbon-producing well.
2. Description of the Related Art
In hydrocarbon wells, fracturing (or “fracing”) is a technique used by well operators to create and/or extend a fracture from the wellbore deeper into the surrounding formation, thus increasing the surface area for formation fluids to flow into the well. Fracing can be accomplished by either injecting fluids into the formation at high pressure (hydraulic fracturing) or injecting fluids laced with round granular material (proppant fracturing) into the formation.
Fracing multiple-stage production wells requires selective actuation of downhole tools, such as fracing valves, to control fluid flow from the tubing string to the formation. For example, U.S. Published Application No. 2008/0302538, entitled Cemented Open Hole Selective Fracing System and which is incorporated by reference herein, describes embodiments for selectively actuating a fracing sleeve that incorporates a shifting tool. The tool is run into the tubing string and engages with a profile within the interior of the valve. An inner sleeve may then be moved to an open position to allow fracing or to a closed position to prevent fluid flow to or from the formation.
That same application describes a system using multiple ball-and-seat tools, each having a differently-sized ball seat and corresponding ball. Ball-and-seat systems address some of the drawbacks of shifting tools because they do not require running such shifting tools thousands of feet into the tubing string. Ball-and-seat systems can be designed to allow a one-quarter inch difference between sleeves and the inner diameters of the seats of the valves within the string. For example, in a 4.5-inch liner, balls from 1.25-inches in diameter to 3.5-inches in diameters can be dropped in one-quarter inch or one-eighth inch increments, with the smallest ball seat positioned in the last valve in the tubing string. This, however, can limit the number of valves that can be used in a given tubing string because in these systems each ball is designed to actuate a single valve and the size of the liner may limit the number of valves with differently-sized ball seats.
The present invention increases system effectiveness and reduces mechanical risk, thereby increasing system reliability while lowering cost. Operators need not be concerned about impacting the shifting ball into a seat at too high of a rate or pressure which may lead in some cases to a failure of the ball or sleeve.
The present invention contemplates a valve seat assembly for actuating a connected downhole tool. The connected downhole tool may be mechanically connected, such as a sleeve positionable between flow ports through a housing, or hydraulically connected, such as through establishing a fluid communication path to the tool to cause actuation thereof. The valve seat assembly generally has a seating element with an having an inlet and an outlet; and a counting element configured to keep a tally of the number times a first pressure at the inlet exceeds a second pressure at the outlet by at least a pre-determined amount.
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 through the tool and wellbore. Thus, normal production of hydrocarbons 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 move from the surface in the downwell direction to the portion of the tubing string within the formation.
The ported sleeve assembly 22 can transition between three states: (i) a neutral position, which is shown in
The ported sleeve assembly 22 comprises a top connection 28 threaded to a housing assembly 30 that includes a spring housing 32, a seal housing 34 having an annular upper end 36, and a ported housing 40. A plurality of radially-aligned ports 42 is disposed through the ported housing 40 to provide a fluid communication path between the interior of the ported sleeve assembly 22 and the surrounding formation.
A sleeve 44 is nested and moveable longitudinally within the housing assembly 30. The sleeve 44 comprises a spring mandrel 46 having an annular shoulder 48 located at the upper end of the sleeve 44, and an upper seal mandrel 50 having an annular lower end 51. A compression spring 62 is positioned within an annular volume defined by the annular shoulder 48 and the annular upper end 36 of the seal housing 34. In the neutral position shown in
A plurality of circumferentially-aligned initiation elements (e.g., shear pins) 41 extend through the ported housing 40 and engage the sleeve 44. The initiation elements are frangible upon application of a predetermined pressure by the sleeve 44.
The sleeve 44 further comprises a lower seal mandrel 52 having an annular middle shoulder 53, and an annular slotted member 54 positioned around the lower seal mandrel 52 and fixed longitudinally between the lower end 51 of the upper seal mandrel 50 and the middle shoulder 53. The slotted member 54 fits snugly around the lower seal mandrel 52, but is freely rotatable thereabout. The sleeve 44 incorporates a valve seat assembly that has a seating element in the form of an annular inner engagement surface 39 that will seal with an appropriately sized and shaped restrictor element (e.g., wiper ball or dart), as will be described infra. The engagement surface 39 comprises a first and second opposing openings 39′, 39″.
As shown in
The torque pin 56 is positioned within the slot 58.
The slot 58 is shaped so that when the torque pin 56 is in a neutral position and the slotted member 54 moves downwell relative to the ported housing 40 (in direction Ddw), the torque pin 56 moves, relative to the slotted member 54, toward the adjacent shifted position. For example, when the torque pin 56 is in the first neutral position 55a and the slotted member 54 moves in direction Ddw, the torque pin 56 travels along the slot 58 to the first shifted position 57a, where further downwell movement of the slotted member 54 is impeded. When the torque pin 56 is in a shifted position, such as the first shifted position 57a, and the slotted member 54 moves upwell in direction Duw, the torque pin 56 travels toward the next adjacent neutral position, which is the second neutral position 55b, or, if the torque pin 56 is at the thirteenth shifted position 57m, to the actuated position 63.
Operation of the embodiment 20 is initially described with reference to
As shown in
After the sleeve 44 has shifted, the continued pressure differential will extrude the ball 80 past the engagement surface 39 and through the sleeve 44. The compression spring 62 will thereafter expand to return the sleeve 44 to either a neutral or the actuated position, depending on the position of the torque pin 56 within the slot 58 (see
As shown in
As shown in
Although the sleeve assembly 22 as described above requires thirteen cycles to actuate the sleeve 44 to the second position if the torque pin 56 is initially positioned at the first end 59 of the slot 58, the number of shifting cycles until actuation may be reduced by positioning the sleeve assembly 22 in the wellbore with the torque pins 56 positioned in one of the intermediate neutral slot positions 55b-55m. For example, the embodiment 20 may be preset to require only four shifting cycles by setting the torque pin 58 to the tenth neutral position 55j prior to installation in the tubing string. Thus, passage of the fourth wiper ball will actuate the sleeve assembly 44 to the second position shown in
To fracture the surrounding formation 100, a first restrictor element is moved through the tubing string and assemblies 22a-22c as described supra. Because the lower assembly 22c is set to only require (i.e., “count”) one shifting cycle for actuation, the lower assembly 22c is opened to permit fluid flow into the surrounding formation 100. When a second restrictor element is passed through the tubing string, the middle ported assembly 22b is opened. The area adjacent to the middle assembly 22b may thereafter be fraced. When a third restrictor element is passed through the tubing string, the upper ported sleeve assembly 22a is opened. The area adjacent to the upper sleeve assembly 22a may thereafter be fraced. After fracturing, the well operator can produce hydrocarbons through the assemblies 22a-22c and downwell of the deepest assembly 22c
The present invention also increases system effectiveness and reduces mechanical risk, thereby increasing system reliability while lowering cost. Operators need not be concerned about impacting the shifting ball into a seat at too high of a rate or pressure which may lead in some cases to a failure of the ball or sleeve.
In one embodiment of a system incorporating the sleeve assembly, a ported sleeve assembly is positioned as a bottom sub, or “toe sub,” in a tubing string having a cemented liner. The assembly is cemented into place within the wellbore. Upon actuation of the ported sleeve assembly following the cycling of pressure through the tool as described supra, pressure may be increased to crack the cement sheath and establish fluid contact to the formation.
In
The firing pin 190 is within pressure chamber 154 proximal to an inlet 155, and is retained in position by a firing pin locking key 176 engaged with a retention groove 200 circumferentially disposed around the firing pin 190. A first end 188 of the firing pin 190 is pressure isolated from a second end 189 with a sealing ring 202. The inlet 155 of each chamber 154 provides a fluid communication path to the flowpath.
The detonator assembly includes a primer 192, primer case 194, shaped charge 196, and an isolation bulkhead 198. The primer 192 is spaced above the firing pin 190 within the primer case 194. The shaped charge 196 is positioned above and adjacent to the primer case 194. The isolation bulkhead 198 is positioned adjacent the shaped charge 194 and proximal to the propellant volume 146. In this position, detonation of the shaped charge will cause corresponding ignition of the propellant volume 146.
Downwell movement of the sleeve 44 causes hydraulic actuation of the firing pin 190 by allowing the firing pin locking key 176 to radially contract into a groove formed into the exterior surface of the sleeve 44. This contraction causes the firing pin locking key 176 to disengage from the firing pin 190.
Pressure thereafter communicated into the pressure chamber 154 causes the firing pin 190 to move upwell because of the pressure differential above and below the sealing ring 202. In other words, because pressure upwell of the sealing element 202 is atmospheric, hydraulic pressure below the sealing element applies a hydraulic force on the second end 189 of the firing pin 190 resulting in upwell movement. While the tool illustrated by the figures shows a sleeve for use in connection with a ported housing, such ported housing is not a required element of the claimed invention. A sleeve of any size, type or shape may be used provided that it, by its relationship with a valve seat, allows activation of the propellant stimulation components in response to a pressure drop across the valve seat.
The housing 322 has a first cylindrical inner surface 330 having a first inner diameter, a second cylindrical inner surface 332 located downwell of the first inner surface 330 and having a second inner diameter that is greater than the first inner diameter, and a third cylindrical inner surface 334 having a third inner diameter that is greater than the second cylindrical inner surface 332. The first inner surface 330 is longitudinally adjacent to the second inner surface 332, forming a downwell-facing shoulder having an annular shoulder surface 338. The second and third inner surfaces 332, 334 are separated by a partially-conical surface 340.
The tool 320 comprises an annular sleeve 348 nested radially within the housing 322 and positioned downwell of the shoulder 338. The sleeve 348 has an upper outer surface 350 with a first outer diameter and a second outer surface 352 with a second outer diameter less than the first inner diameter. The first outer surface 350 and second outer surface 352 are separated by an annular shoulder surface 354. The sleeve 348 further comprises a cylindrical inner surface 356 that extends between annular upper and lower end surfaces 358, 360 of the sleeve 348.
The tool 320 may further comprise a guide element to position the seating element of the valve assembly at the desired location. The guide element in the embodiment of
In the embodiment illustrated by the figures, a C-ring 370 is positioned within the annular sleeve 348 between the upper end surface 358 and the shoulder surface 354. The C-ring 370 fits into a groove formed in the inner surface 356 of the shifting sleeve 348. The groove is sufficiently deep to allow the C-ring seating surface to expand to the desired maximum diameter. In some embodiments, the desired maximum diameter may be as large as or larger than the inner diameter of the shifting sleeve. Those of skill in the art will appreciate that, in embodiments in which the C-ring 370 activates a sleeve or other valve assembly, the C-ring 70 may be positioned at any point along the sleeve or tool, or above or below the sleeve, provided that the C-ring 370 and the sleeve 348 or other tool are connected such that sufficient pressure applied to the C-ring 370 will slide the sleeve in relation to the inner housing or otherwise activate the tool.
The C-ring 370 has an inner surface 374 an outer surface 376 defining the outer perimeter of the C-ring 370, and a seating surface 372 engagable with a restrictor element (e.g., a ball or dart) having a corresponding size. In the illustrated embodiment, the C-ring 370 is held in a radially compressed state by the first inner surface 350 of the housing 322.
The valve seat assembly includes a guide element that has a counting element, a timing element, an indexing element or other device for recording or reflecting the restrictor elements which engage and pass through the assembly or for recording or reflecting the pressure drops which occur across the valve seat which exceed a pre-determined value. In certain embodiments, such as the embodiment illustrated in
In
As indicated with reference to
As those of skill in the art will appreciate, the position of torque pin 400 within the slotted sleeve 348 reflects the number of pressure drops of a pre-determined value which must occur across the C-ring 370, (e.g. the valve seat) before a subsequent pressure drop of will cause actuation of the associated tool. In practice, such pressure drops are created by engaging the C-ring 370, or other valve seat, with a restrictor element. The valve seat thereby “counts” the number of restrictor elements passing the valve seat by indexing from one neutral position to the next. Such counting occurs as a restrictor element engages with the valve seat, enables formation of the required pressure drop, the sleeve moves to the next shifted position, the restrictor element releases from the valve seat, and the sleeve moves, by force of the spring, to the next neutral position. This cycle is repeated with subsequent restrictor elements configured to create the necessary pressure drop across the valve seat (e.g. restrictor elements of the appropriate size and material). In this fashion, the guide element affects the actuation of the tool by indexing from neutral position to neutral position and thereby, in conjunction with the seating element and restrictor element, controls the timing for actuation of the tool.
Referring to
Referring to
In some embodiments, a retaining element, not shown, may be placed in the sleeve to define this intermediate position, such retaining element being set such that it stops movement of the C-ring 370 and sleeve up to a first pressure, but allows movement of the C-ring 370 at a second pressure. Those of skill in the art will appreciate that many retaining elements such as a shear ring, shear pins, or other device may be used in conjunction with the valve assemblies described herein. Further, mechanisms, assemblies, methods or devices other than a retaining element may be used for defining the intermediate third position in a valve assembly and any such method or element is within the scope of the valve assemblies contemplated herein.
Yet another embodiment contemplates a seating element separately attachable to the interior surface of a sleeve and operable with a resilient restrictor element, such as the valve seat assembly shown in U.S. application Ser. No. 13/423,154, filed Mar. 16, 2012 and entitled “Downhole System and Apparatus Incorporating Valve Assembly With Resilient Deformable Engaging Element,” and which is incorporated by reference. In this embodiment, the restrictor element has a resilient portion with a first shape when no more than a first pressure differential is applied across said restrictor element in a direction and a second shape when a second pressure differential is applied across the restrictor element in the same direction. The restrictor element is engagable with the seating element to substantially prevent fluid communication through said sealing section when a pressure differential is applied to the restrictor element that is less than the first pressure differential. The restrictor element is extrudable through said seating element without substantial permanent deformation by applying at least a second pressure differential.
According to another embodiment of the invention, the seating element may comprise a plurality of seat segments interconnected with at least one elastomeric member, as disclosed in U.S. application Ser. No. 12/702,169, filed Feb. 28, 2010 and entitled “Downhole Tool With Expandable Seat,” which is incorporated by reference herein. In this alternative embodiment, the seating element is moveable between a first section of a housing, said first section having a first inner diameter. The housing has a second section downwell from said first section and having a second inner diameter greater than said first inner diameter. The first inner diameter is sized to prevent expansion of the seating element when the seating element is positioned in said first section, whereas the second inner diameter is sized to allow expansion of the expandable seat when in the second position. Any other valve seat-restrictor element combination is within the scope of the claimed invention provided such combination allows the creation of a desired pressure drop across the valve seat, the release of the restrictor element past the valve seat, and the restrictor element is substantially undamaged or otherwise not deformed such that it can form a fluid seal with a subsequently engaged valve seat.
The apparatus and systems are described in terms of embodiments in which a specific system and method are described. Those skilled in the art will recognize that alternative embodiments of such system, and alternative applications of the method, can be used. Other aspects and advantages may be obtained from a study of this disclosure and the drawings, along with the appended claims. Moreover, the recited order of the steps of the method described herein is not meant to limit the order in which those steps may be performed.
This original nonprovisional application claims the benefit of U.S. provisional application Ser. No. 61/475,333 filed Apr. 14, 2011 and entitled “Downhole Tool and System for Producing Hydrocarbons,” which is incorporated by reference herein. This application also claims the benefit of U.S. application Ser. No. 13/423,154, filed Mar. 16, 2012 and entitled “Downhole System and Apparatus Incorporating Valve Assembly With Resilient Deformable Engaging Element,” and Ser. No. 13/423,158, filed Mar. 16, 2012 and entitled “Multistage Production System Incorporating Downhole Tool With Collapsible or Expandable C-Ring,” both of which are incorporated by reference.
Number | Date | Country | |
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61475333 | Apr 2011 | US |