WO2016119066A1

WO2016119066A1 - Downhole isolation valve

Info

Publication number: WO2016119066A1
Application number: PCT/CA2016/050079
Authority: WO
Inventors: John Taskinen; Shawn Mckinnon; James MONTOYA
Original assignee: Snubco Manufacturing Inc.
Priority date: 2015-01-29
Filing date: 2016-01-29
Publication date: 2016-08-04

Abstract

A downhole isolation valve includes (a) a valve housing having a central flow passage, and an internal circular valve seat; (b) a split ball valve comprising two partial spherical portions disposed within the flow passage, each portion rotatable on a transverse axis between an open position, and a closed position wherein the two partial spheres mate with each to form a hemispherical valve seated on the valve seat, which blocks the central flow passage; (c) a sliding member disposed within the valve housing, and moveable between a closed position and an open position by a pressure differential between an upper hydraulic chamber and a lower hydraulic chamber; (d) a vertical actuator engaging the sliding member; and(e) a rotational drive which translates longitudinal movement of the vertical actuator to rotational movement which opens or closes the split ball valve.

Description

DOWNHOLE ISOLATION VALVE

Field of the Invention

[0001] The present invention is directed to a downhole isolation valve. Background

[0002] In drilling and well maintenance operations, it is common practice to include one or more valves connected within a pipe string to separate and control the flow of fluid between various sections of the wellbore. These valves are commonly referred to as formation isolation valves or downhole isolation valves. [0003] Downhole valves are also used to isolate formation pressure during well construction or maintenance. These valves are typically uni-directional valves such as ball valves, discs, flappers or sleeves. A conventional valve such as a flapper valve opens downwards, such that the flow of formation fluids tends to push it shut, whereas pressure from the surface will push the valve open. Thus, this type of valve is often said to be "fail-safe". Conventionally, these valves are controlled hydraulically from the surface, with a hydraulically actuating sleeve or other mechanism which controls the opening and closing of the valve. Separate hydraulic lines run from the surface to the valve. In other valves, electric actuators or motors are used, and internal or external cables are provided to provide power and communications downhole.

[0004] These isolation valves must often be able to withstand great pressures, which may be up to 5,000 psi or more. Most conventional valves are not capable of withstanding pressures in excess of 5,000 psi.

l [0005] The use of separate hydraulic lines, or electric or communication cables often presents difficulties for well operators while assembling and inserting the tubing string into a borehole. Additionally, these cable or lines are subject to corrosion and heavy wear.

[0006] Therefore, there is a need in the art for a robust downhole isolation valve which may be capable of withstanding extreme wellbore pressures, preferably in excess of 5,000 psi. Summary Of The Invention

[0007] The present invention comprises a downhole isolation valve which may be hydraulically actuated by gas or liquid pressure. This device is used to isolate formation pressures from the upper wellbore and surface during well construction and maintenance. The isolation valve may be utilized in all construction phases of the well including but not limited to drilling, cementing, completion, work-over and fracturing.

[0008] In one aspect, the invention comprises a downhole isolation valve comprising: a valve housing having a central flow passage, and an internal circular valve seat;

(b) a split ball valve comprising two partial spherical portions disposed within the flow passage, each portion rotatable on a transverse axis between an open position, and a closed position wherein the two partial spheres mate with each to form a hemispherical valve seated on the valve seat, which blocks the central flow passage; (c) a sliding member disposed within the valve housing, and moveable between a closed position and an open position by a pressure differential between an upper hydraulic chamber and a lower hydraulic chamber;

(d) a vertical actuator engaging the sliding member; and (e) a rotational drive which translates longitudinal movement of the vertical actuator to rotational movement which opens or closes the split ball valve.

[0009] In one embodiment, the vertical actuator and rotational drive comprises a scotch yoke assembly or a slotted link mechanism. In an alternative embodiment, the vertical actuator and rotational drive comprises a rack and pinion assembly.

Brief Description Of The Drawings

[0010] In the drawings, like elements are assigned like reference numerals. The drawings are not necessarily to scale, with the emphasis instead placed upon the principles of the present invention. Additionally, each of the embodiments depicted are but one of a number of possible arrangements utilizing the fundamental concepts of the present invention. The drawings are briefly described as follows:

[0011] Figure 1 shows a partial cutaway view of one embodiment of the present invention. Figure 1 A shows a detailed view of one portion of Figure 1.

[0012] Figure 2 shows a longitudinal cross-section of Figure 1 with the split ball valve in a closed position.

[0013] Fig. 3 is the complete view of the downhole isolation valve using one form of the present invention partly in cross-section and shown in the open position. Figure 3A is a detailed view of one portion of Figure 3.

[0014] Fig. 4 is a partially disassembled view of one embodiment of a downhole isolation valve. [0015] Fig. 5 A is a view of the embodiment of the valve of Figure 4 in the closed position. Fig. 5B is a view of the same valve in an open position.

[0016] Fig. 6 shows a partial cross-section of an alternative embodiment, shown in the open position.

[0017] Figures 7 A and 7B are a continuation of each other, showing the embodiment of Figure 6 in an open position.

[0018] Figures 8A and 8B are a continuation of each other, showing the embodiment of Figure 6 in a closed position.

Detailed Description Of Preferred Embodiments

[0019] The invention relates to a downhole isolation valve. The valve permits for well production and passage of tool strings through the valve, but may be closed in order to isolate formation or wellbore pressures. When describing the present invention, all terms not defined herein have their common art-recognized meanings.

[0020] References to "up", "upward", "top", "above", "down", "downward", "bottom" or below are intended to refer to the orientation of the apparatus in use in a substantially vertical position, however, one skilled in the art will understand that these valves may be used in vertical, slant or horizontal wellbores.

[0021] In one embodiment, a downhole isolation valve of the present invention generally has a central axial flow passage, and includes a housing adapter (10) and valve housing (12) threaded into a tubing string (not shown) by way of the upper and lower tubing connectors (8 and 14) respectively. The components may be threaded together in conventional fashion. In one embodiment, Torque blocks (15) may be provided between components to improve the device's resistance to twisting forces which would tend to uncouple the components.

[0022] In one embodiment, the isolation valve is controlled by hydraulic pressure operating a valve actuating mechanism to move a valve, which comprises a split-ball valve (2), disposed within the valve housing (12). The split-ball valve comprises two partial spherical portions (2A, 2B), which mate together to form a hemispherical ball valve. Each partial spherical portion rotates about a transverse axis (A) between an open position and closed position. In one embodiment, the valve actuating mechanism comprises any mechanical arrangement which converts linear motion into rotational motion, such as a rack and pinion assembly, a scotch yoke assembly, or slotted link assembly. In the closed position, the isolation valve seals the flow passage as the two halves of the split-ball valve (2) are seated along their mating edges, as well as on the valve seat (4), thereby separating and sealing the upper and lower sections of the tubing string from one another.

[0023] In one embodiment, the split-ball valve (2) comprises a substantially hemispherical dome, oriented with an apex on the centerline of the tubing string facing upwards, and is split symmetrically along a plane through the centerline of the flow passage. The two halves of the split-ball valve (2) come together in the closed position forming a contact seal to close the flow passage. Each half of the split- ball may incorporate a step or profile which mate together to improve the seal between the two halves. [0024] The sealing portions of the valve and valve seat may comprise metal-to-metal sealing surfaces, or may comprise high temperature polymer seals, which are well known in the art.

[0025] The differential pressure that actuates the valve is controlled by two internal pressure chambers (3 A, 3B) that are maintained by control lines (20, 21) which run to the well surface. Hydraulic pressure in the upper chamber (3 A) causes a sliding member such as a piston (16) to move downwards, while hydraulic pressure in the lower chamber (3B) causes the sliding member (16) to move upwards. The internal chambers (3 A, 3B) are formed in the annular space between the valve housing (12) and the sliding member (16), and are sealed by O-rings at top and bottom in a conventional manner.

[0026] In one embodiment, one hydraulic chamber may be replaced by a biasing mechanism (not shown) such as a spring or a closed resilient gas chamber, which biases the valve into either the closed or open position. The biasing mechanism may be overcome by hydraulic pressure to either open or close the valve, as the case may be.

[0027] In one embodiment, the valve actuating mechanism comprises a Scotch yoke mechanism in order to open and close the valve. The piston (16) is connected to a drive link (22) which defines at least one transverse slot (24). A circular drive hub (26) has a pin (28) which fits within the slot (24). As is apparent, longitudinal movement of the drive link (22) causes rotation of the drive hub (26). The drive hub is connected to the split ball valve (2) and opens and closes the two halves of the split-ball valve with its rotation. In one embodiment, the drive hub (26) may directly rotate one half (2A) of the split-ball valve, while the other half (2B) is counter-rotated by the first half (2A). Alternatively, separate drive hubs connected to the two halves and which may counter-rotate, are each rotated by the drive link (22). As is shown in Figures 3A and 3B, the drive hub may have about a 90° range of motion, which is sufficient to fully open and close the split-ball valve.

[0028] In an alternative embodiment, as shown in Figure 6, the split-ball valve may be disposed within the valve housing (12) and located by a pinion shaft (100). A sliding sleeve (30) is actuated by differential pressures in the upper and lower hydraulic chambers (3A, 3B), which causes the sleeve to slide vertically within the valve housing (14). The sleeve may be linked to a piston (104) having a toothed rack (105) which rotates a pinion gear (106) to open or close the split-ball valve (2). When lowered completely, the opening sleeve (30) has a lower extension (32) which seats annularly within the split-ball valve (2) opening. Thus, the split-ball valve is held in the open position as long as the opening sleeve (30) is in the downward position. The sleeve (30) and lower extension (32) may act as a debris cover to protect the sealing surfaces of the split ball valve, and the valve seat.

[0029] In one embodiment, a coil spring (1 10) or a similar biasing mechanism is incorporated to bias the valve into its closed position. As shown in Figure 6, the spring (1 10) bears on a shoulder (1 12) and urges the sleeve (30) upward, resulting in the split ball valve (2) closing. In order to open the valve, the pressure in chamber (3) must overcome the combined force of the pressure in chamber (4) and the spring (1 10), as well as any friction between the split ball valve and the valve seat.

[0030] The valve may be actuated in a controlled manner to both the closed and open positions, by the application of fluid pressure to one of the upper and lower internal chambers, or the removal of fluid pressure from one of the upper and lower internal chambers, through control lines (20, 21).

[0031] A rack support guide (106) maintains alignment of the rack (105) to the split-ball valve (2) during opening and closing of the isolation valve elements, and is retained in position annularly by a load ring (108) that compresses the rack support guide (106) upwardly against a footing (1 10) in the valve housing (14). Additionally, the load ring (108) acts as a physical stop for the split-ball valve (2) which has a physical stop for the cylindrical opening sleeve (30) at the full-open position. Thus, movement of the rack piston (104) is limited by the movement of the split-ball valve (2) when it contacts the rack support guide (106) causing the rack piston (104) and rack (105) to halt. The isolation valve (1) achieves a full-open position when the split-ball valve (2) is seated against the load ring (108) and the pressure acting on the opening sleeve (30) from within the upper internal chamber (3A) exceeds the upwardly biasing force of the spring (1 10) and the pressure within the lower internal chamber (3B). The lower extension (32) of the opening sleeve (30) is seated within the open split-ball valve (2). Thus, the split-ball valve (2) is held in the open position as long as the opening sleeve (30) is in the downward position.

[0032] If the differential pressure is biased to favor the lower internal chamber (3B) the result is upward movement of the sliding sleeve (30) against the upper internal chamber (3) causing the sleeve (30) to move in an upward direction, pulling the rack (104) upwardly and closing the split-ball valve (2). A failure to maintain pressure in the control lines (20, 21) would render the isolation valve in a failed state. In that case, the spring (110) would close the valve in the absence of pressure in either of the control lines. [0033] After the split-ball valve is closed, the pressure above the closure may be bled off from the surface of the well to creating a pressure differential across the valve. This pressure will tend to urge the ball valve against the valve seat (4) and is sufficient to keep the split-ball valve in the closed position. Generally the pressure below the closed isolation valve is expected to be higher than the regulated pressure above, resulting in friction between the split- ball valve (2) and the valve seat (4). However the actuation of the split-ball valve (2) by the rack (104) or the drive hub (26), is near the axis of rotation for the shaft (100) requiring a lower net differential pressure between the upper and lower internal chambers to overcome the friction and open the valve. Furthermore, the force required to overcome the friction between the seals and the inner wall of the valve housing during translation of the cylindrical opening sleeve and the rack piston is overcome by the control of the differential pressure between the upper and lower internal chambers.

[0034] The isolation valve (1) may be assembled prior to deployment into the well and is tied into a tubing string using methods common to drilling subterranean wells and well known by those skilled in the art. The upper and lower tubing connectors (8, 14), the valve housing (14), and the lower tubing connector (12) are threaded together in series to form the external casing (40) of the isolation valve. In one embodiment, torque blocks (15) are installed across the threaded joints to ensure that the isolation valve (1) sections remain threaded together during well construction and maintenance. In one embodiment, the isolation valve is installed in the open position and is actuated to the closed position whenever necessary. The downhole depth of the isolation valve is controlled by the position of the valve (1) in the tubing string when it is placed. Definitions and Interpretation

[0035] The description of the present invention has been presented for purposes of illustration and description, but it is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope of the invention. Embodiments were chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use

contemplated. To the extent that the description is of a specific embodiment or a particular use of the invention, it is intended to be illustrative only, and not limiting of the claimed invention.

[0036] The corresponding structures, materials, acts, and equivalents of all means or steps plus function elements in the claims appended to this specification are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. [0037] References in the specification to "one embodiment", "an embodiment", etc., indicate that the embodiment described may include a particular aspect, feature, structure, or characteristic, but not every embodiment necessarily includes that aspect, feature, structure, or characteristic. Moreover, such phrases may, but do not necessarily, refer to the same embodiment referred to in other portions of the specification. Further, when a particular aspect, feature, structure, or characteristic is described in connection with an embodiment, it is within the knowledge of one skilled in the art to combine, affect or connect such aspect, feature, structure, or characteristic with other embodiments, whether or not such connection or combination is explicitly described. In other words, any element or feature may be combined with any other element or feature in different embodiments, unless there is an obvious or inherent incompatibility between the two, or it is specifically excluded. [0038] It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for the use of exclusive terminology, such as "solely," "only," and the like, in connection with the recitation of claim elements or use of a "negative" limitation. The terms "preferably," "preferred," "prefer," "optionally," "may," and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention.

[0039] The singular forms "a," "an," and "the" include the plural reference unless the context clearly dictates otherwise. The term "and/or" means any one of the items, any combination of the items, or all of the items with which this term is associated. As will also be understood by one skilled in the art, all language such as "up to", "at least", "greater than", "less than", "more than", "or more", and the like, include the number recited and such terms refer to ranges that can be subsequently broken down into sub-ranges as discussed above. In the same manner, all ratios recited herein also include all sub-ratios falling within the broader ratio. .

Claims

WHAT IS CLAIMED IS:

1. A downhole isolation valve comprising:

(a) a valve housing having a central flow passage, and an internal circular valve seat;

(b) a split ball valve comprising two partial spherical portions disposed within the flow passage, each portion rotatable on a transverse axis between an open position, and a closed position wherein the two partial spheres mate with each to form a hemispherical valve seated on the valve seat, which blocks the central flow passage;

(c) a sliding member disposed within the valve housing, and moveable between a closed position and an open position by a pressure differential between an upper hydraulic chamber and a lower hydraulic chamber;

(d) a vertical actuator engaging the sliding member;

(e) a rotational drive which translates longitudinal movement of the vertical actuator to rotational movement which opens or closes the split ball valve.

2. The valve of claim 1 wherein the vertical actuator comprises a rack gear and the rotational drive comprises a pinion gear.

3. The valve of claim 1 wherein the rotational drive comprises a scotch yoke or a slotted link assembly.

4. The valve of claim 2 wherein the sliding member comprises an opening sleeve.

5. The valve of claim 4 wherein the opening sleeve is biased in its open position by a coil spring disposed between the housing and the opening sleeve.

6. The valve of claim 4 wherein the opening sleeve has a lower extension which is positioned inside the open split ball valve when the opening sleeve is in its open position.

7. The valve of claim 3 wherein the sliding member comprises a piston and/or the vertical actuator comprises an elongate drive link and/or the rotational drive comprises a scotch yoke.

8. The valve of claim 7 wherein the drive link comprises at least one pin which reciprocates within a slot defined in a drive hub, wherein rotation of the drive hub causes direct or indirect rotation the partial spheres.

9. The valve of claim 8 wherein the drive link comprises two pins which each reciprocate within a first slot defined in a first drive hub and a second slot defined in a second drive hub, wherein rotation of the first drive hub causes rotation of one partial sphere and rotation of the second drive hub causes rotation of the other partial sphere.

10. The valve of one of claims 2, 4, 5 or 6 further comprising a rack support guide disposed within the housing and engaging a lower portion of the rack gear, and a load ring which retains the rack support guide within the housing.

1 1. The valve of claim 10 wherein the partial spheres contact the load ring when in their fully open position and prevents further movement in an open direction.

12. The valve of any previous claim wherein each partial sphere comprises a mating edge having a profile which complements the profile of the opposing mating edge.