Assembly for Actuating a Downhole Tool

Abstract

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.

Description

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND

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.

BRIEF SUMMARY

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.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a sectional side elevation of a preferred embodiment of the apparatus of the present invention in a neutral state.

FIG. 1A is an enlarged view of window 1A of FIG. 1.

FIGS. 2A and 2B are isometric front and rear views of the slotted member shown in FIG. 1.

FIG. 2C shows the footprint of the slot formed in the exterior surface of the slotted member shown in FIGS. 2A and 2B.

FIG. 3 is intentionally omitted.

FIG. 4 is a side sectional elevation of the embodiment shown in FIG. 1 in a shifted state.

FIG. 4A is an enlarged view of window 4A of FIG. 4.

FIG. 5 is a side sectional elevation of the embodiment shown in FIG. 1 in an actuated state.

FIG. 5A is an enlarged view of window 5A of FIG. 5.

FIG. 6 is a side elevation of a system incorporating multiple ported sleeves of the preferred embodiment shown in FIG. 1.

FIG. 7 is a sectional elevation of a pressure chamber and firing pin of a second embodiment of the invention.

FIG. 8 is a sectional elevation of the firing assembly and pressure chamber shown in FIG. 7 wherein the firing pin has been released and has impacted the primer.

FIG. 9 shows components of yet another embodiment of a valve assembly that comprises a C-ring.

FIG. 10 is a front elevation for the C-ring of FIG. 9

FIG. 11 is a sectional view through line 11-11 of FIG. 9.

FIG. 12 shows the embodiment of FIG. 9 with the sleeve and valve assembly in a shifted position.

FIG. 13 is a sectional view through line 13-13 of FIG. 12.

FIG. 14 shows the embodiment of FIG. 9 with the sleeve and valve assembly in an actuated position.

DETAILED DESCRIPTION

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.

FIG. 1 depicts a valve seat assembly 22 in which the tool to be actuated is a ported sleeve. A tubing string section 26 provides a fluid communication path between the ported sleeve assembly 22 and other downhole tools or accessories.

The ported sleeve assembly 22 can transition between three states: (i) a neutral position, which is shown in FIG. 1; (ii) a “shifted” position, as shown in and described with reference to FIG. 4; and (iii) an “actuated” position, as shown in and described with reference to FIG. 5. When used with reference to a normally-closed ported sleeve assembly, “actuated” means that the ports are opened to allow radial flow of fluid therethrough.

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 FIG. 1, the compression spring 62 is under approximately three-hundred pounds of compression.

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 FIG. 1A, the valve seat assembly includes a guide element that has a counting element. The counting element includes a guiding member, such as a torque pin 56, and a slot 58 formed in the exterior surface 60 of the slotted member 54. The torque pin 56 is fixed relative to, and extends through, the ported housing 40.

The torque pin 56 is positioned within the slot 58. FIGS. 2A-2C show the slotted member 54 and the slot 58 in more detail. The slot 58 is a continuous path formed of intersecting discrete, straight path segments, the path extending radially around and formed in the exterior surface 60 of the slotted member 54. The intersections of the slot segments of the slot 58 form a repeated pattern of thirteen neutral positions 55a-55m and thirteen shifted positions 57a-57m positioned between a first end 59 and a second end 61. The first end 59 of the slot 58 terminates in the first neutral position 55a. The second end 61 of the slot 58 terminates with an actuated position 63 positioned downwell of the neutral positions 55a-55m.

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 FIG. 1. During installation, the embodiment 20 is positioned in a wellbore with the torque pin 56 positioned at the first end 59 of the slot 58 (see FIG. 2C), which is in the first neutral position 55a. In this neutral state or position, the sleeve 44 is positioned radially between the plurality of ports 42 and the flowpath to prevent fluid flow to and from the surrounding formation.

As shown in FIG. 4, to shift the sleeve assembly 22 from a neutral position to a shifted position, the well operator pumps a restrictor element (e.g., ball) 80 downwell to the sleeve assembly 22. In the illustrated embodiment, the ball 80 is larger than the inner diameter of the seating element 39 that is the engagement surface of the sleeve 44. The ball 80 passes through the first opening 39′, which functions as an inlet, and seals to the engagement surface 39 of the sleeve 44, thus creating a friction pressure against it. Although the expansive force of the compression spring 62 resists downwell movement of the sleeve 44, when the pressure differential across the ball 80 exceeds a first pressure differential, the expansive force of the compression spring 62 is overcome and the sleeve 44 moves to the second position shown in FIG. 4, thus positioning the torque pin 56 in the next shifted position of the slotted member 54, depending on the position of the torque pin 56 within the slot 58 prior to shifting. In this manner, the torque pin 56 and slot 58 operate to keep a tally of the number times the pressure differential created across the ball between the inlet 39′ and the outlet 39″ exceeds a first pressure differential by at least a pre-determined amount. Because slot 58 contains a predetermined number of slot positions the slotted member 54, torque pin 56 and slot 58 can be used to effectively count the number of balls that are extruded through the sleeve assembly 22 or the number of times a pressure differential is created between the inlet and the outlet exceeds a first pressure differential by at least a pre-determined amount. The positioning of torque pin 56 and slot 58 in slotted member 54 indexes the number of times the sleeve assembly 22 is shifted and tabulates the number using the positioning of torque pin 56 and slot 58 to enable a plurality of stages using multiple sleeve assemblies to be used because particular sleeve assemblies can be actuated with precision and at predetermined times or stages.

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 FIG. 2C).

As shown in FIG. 2C, the sequence described above is repeatable for the sleeve 44 until the torque pin 56 is positioned in the final neutral position 55m of the upper slot 58m. Thereafter, the next ball passing through the sleeve 44 will move sleeve 44 and position the torque pin 56 to move to the final shifted position 57m of the slot 58. After the ball passes through the sleeve 44 as described supra, the compression spring 62 will urge the spring return 46 upwell until the torque pin 56 is positioned in the actuated position 63. While the embodiments illustrated in the figures show 13 neutral and shifted positions, any plurality of neutral and shifted positions are contemplated in the scope of the present invention. Further, the number of neutral and shifted positions are preferably the same, but differing numbers of neutral and shifted positions may be included in embodiments encompassed by the claimed invention.

As shown in FIG. 5, when the first torque pin 58 is located in the actuated position 63 of the slot 58, the sleeve 44 is in a second position upwell of the ports 42, thereby permitting fluid flow into the surrounding formation from the flowpath. In this state, the compression spring 62 is under minimal, if any, compression.

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 FIG. 5. Moreover, slotted member 54 is not limited to thirteen slot positions but rather the number of slots can be increased or decreased.

FIG. 6 shows a system comprising three ported sleeve assemblies 22a-22c installed in a formation production well drilled in a hydrocarbon producing formation 100 that has three stages 100a-100c. Each of the ported sleeve assemblies 22a-22c is configured to require a different number of shifting cycles prior to actuating: the lower sleeve assembly 22c is located in the lower stage 100c and is set to actuate after one shifting cycle (i.e., the guiding member is initially positioned in neutral position 55m of FIG. 2C); the middle sleeve assembly 22b is located in the middle stage 100b and is set to actuate after two shifting cycles (i.e., the guiding member is initially positioned in neutral position 55l); and the upper sleeve assembly 22a is located in the upper stage 100a and is set to actuate after three shifting cycles (i.e., the guiding member is initially positioned in neutral position 55k).

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 FIGS. 1-6, a valve seat assembly is incorporated into a ported sleeve assembly and described with reference to actuation of a ported sleeve for use in fracturing application. The valve seat assembly described supra, however, may be used to actuate any number of downhole tools, including flapper valves, stimulation devices, packers, and the like.

FIG. 7, for example, shows a section of a sleeve assembly as described supra that further comprises propellant stimulation components. More specifically, FIG. 7 is a side sectional view of a detonator assembly 158 and a firing pin 190 positioned with a pressure chamber 154 formed in the assembly. One or more such pressure chambers 154 may be positioned within the tool.

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.

FIG. 8 shows the detonator assembly 158 with the pressure chamber 154 after the firing pin locking key 176 has released the firing pin 190 and at the point of contact of the firing pin 190 with the primer 192. The sealing ring 202 between the first end 188 and second end 189 of the firing pin 190 isolates pressure in the pressure chamber 154 upwell of the sealing ring 202 from the pressure in the flowpath. After ports 174 are aligned with the inlet 155, pressure within the flowpath is communicated through the ports 174 into the pressure chamber 154 at a position below the sealing element 202, resulting in a pressure differential that moves the firing pin 190 upwell to contact and detonate the primer 192. Detonation of the primer 192 is contained by the case 194 and causes detonation of the adjacent shaped charge 196, which transfers explosive energy to the propellant volume 146, causing ignition thereof. The explosive energy is directed radially outwardly in the form of pressure waves and into the surrounding formation. By use of the valve seat assembly described herein, detonation may be timed to actuate following a preset number of pressure increases resulting from seating, and subsequent passage, of a restrictor element between the first and second openings 39′, 39″ of the engagement surface 39.

FIG. 9 shows a tool 320 actuatable by a valve seat assembly having a slotted sleeve 348 and a torque pin 400. The tool 320 comprises a housing 322 connected to a bottom connection 324 at a threaded section 326. The housing 322 has a plurality of radially-oriented, circumferentially-aligned ports 328 providing communication paths to and from the exterior of the tool 320.

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 FIG. 9 is a spring 364 residing in an annular spring return space 362. The annular spring return space 362 is partially defined by the second outer surface 352 of the sleeve 348 and the third inner surface 334 of the housing 322. The spring return space 362 is further defined by the upper end surface 347 of the bottom connection 324, the partially-conical surface 340 of the housing 322, and the shoulder surface 354 and first outer surface 350 of the sleeve 348.

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 FIG. 9, a counting element includes a guiding member, such as a torque pin 400, and a slot 402 formed in the exterior surface 361 of the sleeve 348. The torque pin 400 is fixed relative to, and extends through, the housing 322 and bottom connection 324.

In FIG. 9, the torque pin 400 is positioned in a “neutral” position of the slot 402, which is identical to the slot shown in and described with reference to FIGS. 2A-2C and is a continuous path formed of intersecting discrete, straight path segments. The slot 402 extends radially around, and is formed in, the exterior surface 361 of the sleeve 348. The guiding element is positioned in a neutral position of the slot 402, with the upper end 358 of the sleeve 348 positioned below the ports 28.

As indicated with reference to FIGS. 1-6, the sleeve 348 can transition between three positions: (i) a neutral position, which is shown in FIG. 9; (ii) a “shifted” position, as shown in and described with reference to FIG. 12; and (iii) an “actuated” position, as shown in and described with reference to FIG. 14. When used with reference to a normally-open ported sleeve assembly, “actuated” means that the ports are closed to inhibit radial flow of fluid therethrough.

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.

FIG. 10 shows a front elevation of one embodiment of the C-ring 370 in a normal uncompressed state. In this embodiment, the outer surface 376 of the C-ring 370 is castellated with a plurality of radial protrusions 378, said radial protrusions defining the outer diameter of the C-ring 370. The circumference of the outer surface of the C-ring 370 may be larger than the circumference of inner surface 356 of the sleeve 348. The C-ring 370 has a machined slot 380 forming terminal ends 382. The slot 380 shown in the illustrative figures is within a protrusion 378, but the slot 380 may be formed at any point along the C-ring 370 and does not have to be formed in a protrusion 378.

Referring to FIG. 11, each of the radial protrusions 378 of the illustrated C-ring 370 is aligned with and extends through an opening 384 in the sleeve 348 between the first outer surface 350 and the inner surface 356. When the C-ring 370 is upwell of the partially-conical shoulder 340 of the housing 322, the C-ring 370 has the operating diameter shown in FIG. 11 and terminal ends 382 of C-ring 370 are in contact to form the seat defined by the seating surface 372. An associated restrictor element may thereafter seat against the seating surface 372 and a pressure differential created across the restrictor element to move the sleeve 348 in the downwell direction.

FIGS. 12-13 show the tool 320 with the sleeve 348 in a shifted position, which is downwell of the position shown in FIG. 9. The coil spring 364 is under compression between the sleeve 348 and the bottom connection 324, with the upper end coil 366 of the spring 364 in contact with the sleeve shoulder 354 and the spring lower end 368 is in contact with the upper end surface 347 of the bottom connection 324. In this position, the spring 364 exerts an expansive force to urge the sleeve 348 in the upwell direction relative to the bottom connection 324. The torque pin 400 is positioned in a “shifted” position of the slot 402.

Referring to FIG. 13, the C-ring 370 is positioned adjacent to the second inner surface 334. Because the second inner surface 334 has a larger diameter than the first inner surface 332, the C-ring 370 radially expands towards its uncompressed shape shown in FIG. 10. The protrusions 378 extend past the outer surface 350 of the sleeve 348, opening the seating surface 372 and allowing the associated restrictor element to pass through the C-ring 370, after which the spring 364 pushes against the sleeve shoulder 354 to move the sleeve 348 upwell.

FIG. 14 shows the sleeve 348 in an actuated position in which fluid flow to the exterior of the tool 320 is inhibited by the sleeve 348. The C-ring 370 is held in a closed state by the second inner surface 332 of the housing 322. The torque pin 400 is positioned in an “actuated” position of the slot 402. In one alternative embodiment, the C-ring 370 may be adjacent to an additional inner surface, not shown, which is sufficiently large to allow the C-ring to expand into its uncompressed state. Further, the claimed invention also encompasses embodiments in which the valve assembly is moved to the actuated position by downwell movement past the shifted position. In such an embodiment, a device which locks the valve assembly in the actuated position may be desirable in order to hold the valve assembly in place against the force of the spring 364.

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.

Claims

1. A valve seat assembly for use in a well for oil, gas or other hydrocarbons, said valve assembly comprising: a seating element having an inlet and an outlet; anda counting element;wherein said counting element is 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.

2. The valve assembly of claim 1 further comprising an initiation element configured to prevent said counting element from keeping said tally until after such initiation element is actuated.

3. The valve assembly of claim 1 further comprising an activation element, wherein said activation element is configured to actuate a downhole tool when said tally reaches a desired number.

4. The valve assembly of claim 1 further comprising: an restrictor element with a resilient portion having a first shape when no more than a first pressure differential is applied across said engaging element in a direction and a second shape when a second pressure differential is applied across the restrictor element in the direction;wherein said restrictor element is engagable with the first 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; andwherein said restrictor element is extrudable through said seating element without substantial permanent deformation by applying at least the second pressure differential.

5. The valve seat assembly of claim 1 wherein said seating element comprises: a plurality of seat segments interconnected with at least one elastomeric member, and wherein said seating element is moveable between a first section of a housing, said first section having a first inner diameter, and said housing further comprises a second section downwell from said first section and having a second inner diameter greater than said first inner diameter; andwherein said first inner diameter is sized to prevent expansion of said expandable sleeve when said expandable sleeve is positioned in said first section, and said second inner diameter is sized to allow expansion of said expandable sleeve when said expandable sleeve is in said second section.

6. The valve seat assembly of claim 1 further comprising: an annular sleeve having an inner surface with a diameter, a first cylindrical outer surface, and a plurality of openings extending between said inner surface and said first cylindrical outer surface, wherein said annular sleeve further comprises a second cylindrical outer surface having a different diameter than the first cylindrical outer surface;wherein said seating element comprises a first C-ring having a body with a seating surface, opposing terminal ends, and an outer diameter extending from the body, wherein the first C-ring is at least partially within the inner surface of the sleeve; anda coil spring positioned around a portion of the sleeve and in an annular space at least partially defined by an annular body and the second cylindrical outer surface.

7. The valve assembly of claim 1 wherein said counting element comprises a slotted sleeve.

8. The valve assembly of claim 1 wherein said counting element comprises a slotted sleeve having a plurality of neutral positions, a plurality of shifted positions, and at least one actuated position.

9. A valve assembly for use in a well for oil, gas or other hydrocarbons, said valve assembly comprising: a seating element, said seating element comprising an inlet and an outlet; anda counting element;wherein said counting element is configured to keep a tally of restrictor elements of a desired size range and deformability range that pass through said seating element.

10. The valve assembly of claim 7 further comprising an initiation element, said initiation element configured to prevent said counting element from keeping said tally until after such initiation element is actuated.

11. The valve seat assembly of claim 7 further comprising an activation element, wherein said activation element is configured to actuate a downhole tool when said tally reaches a desired number.

12. A valve seat assembly for use in a well for oil, gas or other hydrocarbons, said valve seat assembly comprising: a path for the flow of fluids through the valve seat assembly;a seating element configured to receive a restrictor element and thereby reduce or eliminate the flow of fluids through the path;a guide element comprising: a counting element configured to keep a tally of restrictor elements having desired characteristics that pass through said seating element, andan activation element,wherein when said tally reaches a predetermined value, said activation element is actuated and said valve assembly actuates a tool in communication with said assembly.

13. The valve assembly of claim 10 wherein said counting element is a slotted sleeve.

14. The valve assembly of claim 10 where said initiation element is a shear pin.

15. A valve assembly for use with a downhole tool, said valve assembly comprising: a seating element, said seating element comprising an inlet and an outlet, anda guide element having a counting member;wherein said seating element is configured to engage a restrictor element and thereby reduce or prevent the flow of fluid from said inlet to said outlet,said seating element is engaged with said guide element such that said guide element is configured to prevent actuation of said tool through a first cycle of pressure increase and decrease; andsaid guide element is configured to permit actuation of said tool during an activation cycle, which occurs subsequent to said initiation cycle.

16. The valve assembly of claim 13 further comprising a plurality of restrictor elements.

17. The valve assembly of claim 13 wherein said guide element is configured to prevent actuation of said tool through a plurality of indexing cycles.

18. A downhole tool for use in a production well having a tubing string defining a flowpath, the downhole tool comprising: a ported housing having a plurality of ports disposed radially therethrough;a sleeve at least partially within said ported housing and moveable between a first position and a second position, wherein in said first position said sleeve is radially positioned between said plurality of ports and said flowpath, said sleeve having an upper end, an exterior surface, a slot formed in said exterior surface, and an engagement surface having a first inner diameter;a guiding member fixed relative to said housing and positionable within said slot; anda compression spring positioned between said upper end of said sleeve and said ported housing, said compression spring being under compression when said sleeve is in said first position.

19. The downhole tool of claim 16 further comprising: a C-ring having first and second terminal ends defining a split and a plurality of radially-extending protrusions, said C-ring being moveable between a compressed state, wherein the ends of the C-ring are in contact to form a closed seat, and an uncompressed state;wherein said sleeve has an interior surface, an exterior surface, and a groove formed in said interior surface with a plurality of openings extending between said interior and exterior surfaces, said openings aligned to receive with said plurality of radially extending protrusions;wherein said housing has a first inside diameter and a second inside diameter that is larger than said first inside diameter;wherein when said groove is positioned within said first inside diameter, said protrusions hold said C-ring in an at least substantially compressed state; andwherein when said groove is positioned within said second inside diameter, the C-ring is in an at least substantially uncompressed state.

20. The downhole tool of claim 17 further comprising: a propellant volume;an annular portion with at least one pressure chamber having an end positioned adjacent to said propellant volume and an inlet providing a communication path to said flowpath;at least one detonator assembly within said at least one pressure chamber proximal to said end;at least one firing pin within said at least one pressure chamber, said at least one firing pin having a first end pressure isolated from a second end;a second section having a plurality of flow ports defining a fluid communication path between said flowpath and the exterior of the downhole tool;wherein said sleeve is moveable between a first position and a second position, wherein in said first position said sleeve assembly is between said plurality of flow ports and said flowpath and between the inlet of said at least one pressure chamber and said flowpath.

21. A system for producing hydrocarbons from a well wherein the downhole tool of claim 16 is positioned as a bottom sub.

22. A valve seat assembly for use in a well for oil, gas or other hydrocarbons, said valve assembly comprising: a seating element having an inlet and an outlet; anda guide element;wherein said guide element is configured to reflect the number times a first pressure at the inlet exceeds a second pressure at the outlet by at least a pre-determined amount.

23. The valve seat assembly of claim 22, said guide element further comprises a timing element wherein said timing element causes actuation of a tool when the number of times said first pressure exceeds said second pressure by at least a pre-determined value reaches a desired number.

24. The valve seat assembly of claim 22, said guide element further comprises a timing element wherein said timing element allows actuation of a tool when the number of times said first pressure exceeds said second pressure by at least a pre-determined value reaches a desired number.

25. An assembly for actuating a downhole tool in a production well having a tubing string defining a flowpath, the assembly comprising: a housing;an annular body at least partially within said housing and moveable between a first position and a second position, said annular body having an upper end, a lower end, an exterior surface, a slot formed in said exterior surface;a guiding member fixed relative to said housing and positionable within said slot; anda spring positioned between said upper end of said annular body and said housing, said spring being under compression when said annular body is in said first position;wherein said slot has a continuous path between a first and second end formed of intersecting segments forming a repeated pattern of circumferentially-aligned first positions and circumferentially-aligned second positions positioned between said first end and said second end, and wherein the first end intersects one of said first positions and said second end is positioned longitudinally between said first positions and said lower end of said annular body.

26. The assembly of claim 25 wherein said annular body is a sleeve having a seating element with an engagement surface having an inner diameter sized to engage with a corresponding restrictor element.

27. The assembly of claim 25 wherein said annular body is a slotted member fixed relative to a seating element with an engagement surface having an inner diameter sized to engage with a corresponding restrictor element.