INVENTOR(S): SHAIKH, Farhat A.; and CIVAROLO, Marcelo F.

FIELD OF THE DISCLOSURE

[0001] This disclosure pertains generally to flow control devices such as valves.

BACKGROUND OF THE DISCLOSURE

[0002] During the drilling and completion of oil and gas wells, the downhole environment can impose substantial operational stresses on downhole equipment. These harsh conditions exposure to drilling mud, contaminants entrained in well fluids, and hydraulic forces of the circulating drilling mud. Extreme pressures and temperatures may also be present. Such harsh conditions can damage and degrade downhole equipment. Valves used in sampling, drilling, and completion operations may be susceptible to the harsh downhole conditions because they require the use of seals and moving parts. For example, valves used in a downhole environment may interact with deleterious debris carried by formation fluids and encounter significant pressure drops.

[0003] The present disclosure addresses the need for sealing high differential pressure in a downhole environment, as well as in surface applications.

SUMMARY OF THE DISCLOSURE

[0004] In aspects, the present disclosure provides an apparatus for controlling a fluid flow in a borehole. The apparatus may include a tool body configured to retrieve a fluid sample from a subsurface formation, the tool body having a fluid conduit having an inlet for receiving the fluid sample and an outlet for conveying the fluid sample to a selected location; a mandrel selectively blocking flow across the fluid conduit; and a seal disposed on the mandrel, the seal including at least one chevron seal element configured to cooperate with the mandrel to selectively block flow across the fluid conduit. [0005] In another embodiment, the apparatus may include a carrier configured to be conveyed along a borehole; a tool body positioned along the carrier, the tool body having at least one packer configured to form an isolated zone, the tool body having a fluid conduit having an inlet for receiving a fluid sample from the isolated zone and an outlet for conveying the fluid sample to a selected location; and a valve disposed in the tool body. The valve may include a mandrel configured to translate between a first and a second position to selectively block flow across the fluid conduit; and a seal disposed on the mandrel, the seal including at least one chevron seal element configured to cooperate with the mandrel to selectively block flow across the fluid conduit.

[0006] In another aspect, the present disclosure provides a method for controlling a fluid flow. The method may include retrieving a fluid sample from a subsurface formation using a tool body, the tool body having a fluid conduit having an inlet for receiving the fluid sample and an outlet for conveying the fluid sample to a selected location; selectively blocking flow across the fluid conduit using a mandrel; and isolating the inlet from the outlet using a seal positioned in a passage between the mandrel and the tool body, the seal including at least one chevron seal element.

[0007] Thus, the present disclosure provides seals that enhance control, operation, service life, reliability, and / or performance for valves and other flow control devices. The teachings may be applied to a variety of systems both in the oil and gas industry and elsewhere.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] For a detailed understanding of the present disclosure, reference should be made to the following detailed description of the embodiments, taken in conjunction with the accompanying drawings, in which like elements have been given like numerals, wherein:

FIGS. 1A and IB shows sectional views of a valve according to one embodiment of the present disclosure in the open and closed positions, respectively;

FIG. 2 shows a seal in accordance with one embodiment of the present disclosure; and FIG. 3 schematically shows a well system that uses a valve according to one embodiment of the present disclosure in a borehole formed in an earthen formation.

DETAILED DESCRIPTION

[0009] In aspects, the present disclosure provides a "dirty" fluid valve with a bi-directional Chevron type metal seal assembly for use in tool used to sample wellbore fluids and to store such fluids in a sample bottle. The valve may be pressure balanced and may be operated in varying pressures. The seals described herein provide gas tight seal for repeated operations.

[0010] Referring initially to FIGS. 1A and IB, there is shown a valve assembly 10 that may be used to retrieve fluid samples from a formation. The valve assembly 10 may include a body or housing 20 in which a mandrel 30 and a seal 40 are disposed. The housing 20 may include a fluid inlet 22, a fluid outlet 24, pressure chambers 26a, b, and pilot holes 28a, b. The pressure chamber 26a is positioned next to a first end 32 of the mandrel 30 and the pressure chamber 26b is positioned next to a second end 34 of the mandrel 30. The housing 20 may be unitary or composed of several components. Therefore, it should be understood that the depicted configuration is merely illustrative and does not limit the present disclosure.

[0011] In one embodiment, fluid communication between the fluid inlet 22 and the fluid outlet 24 may be controlled by shifting or translating the mandrel 30 in a cavity 42 of the housing 20. The mandrel 30 may be a cylindrical member that includes a reduced diameter or "necked" portion 31. When the mandrel 30 is set in the open position, the necked portion 31 forms an annular passage 48 in the housing that 20 that connects the fluid inlet 22 with the fluid outlet 24. Thus, the inlet 22, the passage 42, and the outlet 24 may be considered as forming a fluid conduit in the housing 20. Seals 62, 64 between the mandrel 30 and the housing 20 isolate the passage 48 from the rest of the valve 10. To shift the mandrel 30 to the open position, the pressure chamber 26b is pressurized using the pilot inlet 28b to urge the mandrel 30 in an axial direction marked with arrow 44. To shift the mandrel 30 to the closed position, the pressure chamber 26a is pressurized using the pilot inlet 28a with a hydraulic fluid to urge the mandrel 30 in an axial direction marked with arrow 46, which is directionally opposite to arrow 44.

[0012] Referring now to FIG. 1A, the valve assembly 10 is shown in an open position wherein the fluid inlet 22 and the fluid outlet 24 are in fluid communication via a passage 48 in the housing 20. Applying pressurized hydraulic fluid to the pressure chamber 26a slides the mandrel 30 in the axial direction 44 until the mandrel 30 reaches the closed position shown in FIG. IB. In FIG. IB, the seal 40 and the mandrel 30 form a fluid seal (e.g., liquid-tight seal or gas-tight seal) that prevents fluid communication between the fluid inlet 22 and the fluid outlet 24.

[0013] Referring to FIG. IB, the seal 40 may be a bidirectional sealing device that includes one or more sealing elements that form a flow-blocking barrier between an outer surface 44 of the mandrel 30 and an inner surface 46 of the housing 20. The seal 40 may be bidirectional in that the seal prevents flow therethrough in either axial direction. The seal 40 surrounds the mandrel 30 and is stationary relative to the housing 20. For example, the seal 40 may seat on a support 47 of the housing 20. The support 47 may be a shoulder or ledge that limits axial movement of the seal 40. The support 47 may be integral with the housing 20 or tubular component of the housing 20.

[0014] Referring now to FIG. 2, there is shown a cross-sectional view of a section of one embodiment of a seal 40 in accordance with the present disclosure. In one arrangement, the seal 40 may include an upper end adapter 48a, a first unidirectional seal stack 50a, a center adapter 52, a second unidirectional seal stack 50b, and a second end adapter 48b. The end adapters 48a,b and the center adapter 52 may be formed of a material harder or more rigid than the material of the seal rings 54 so that pressure applied to the end adapters 48a, b can be distributed relatively evenly through the seal stacks 50a,b.

[0015] The unidirectional seal ring stacks 50a, b may include one or more cylindrical seal rings 54. The seal rings 54 may be formed as chevron- type seal rings. As used herein, a chevron seal ring is a pressure responsive sealing element that flexes to form a seal against adjacent surfaces. The chevron shape may defined by two wings 56 that are hinged at an apex 58. The wings 56 may form an angle less than one-hundred eighty degrees. The seal ring 54 is responsive to the pressure applied on the apex 58 side (i.e. , unidirectional). In one embodiment, the seal rings 54 may be "U" or "V" shaped annular elements formed of a material that allows a predetermined amount of flexure when the ring 54 is compressed. Thus, pressure applied to the upper end adapter 48a causes the ring(s) 54 to be compressed against the center adapter 52. This compression causes the ring(s) 54 to expand and compress the tips 60 of the wings 56 to engage and seal against the adjacent surfaces 44, 46.

[0016] It should be appreciated that seal 40 is pressure responsive in that the magnitude of the sealing force (or contact force) at the tips 60 varies directly with the differential pressure across the seal 40. Thus, as this pressure differential increases, the sealing force at the tips 60 also increases. In the embodiment shown, the seal 40 includes multiple oppositely-oriented rings 54. The use of multiple rings 54 allows the formation of multiple serially aligned sealing surfaces along the surfaces 44, 46. The opposite orientation of the seal rings 54, i.e. , having the apexes 58 point in opposite directions, enables the seal 40 to be bidirectional.

[0017] The rings 54 may be formed of a material that has a modulus that allows flexure at a prescribed pressure range. In some embodiments, a metal such as spring steel may be used. In other embodiments, non-metals such as elastomeric material may used. In still other embodiments, the seal stacks 50a, b may use a combination of two or more materials. For example, seal stacks 50a, b may include one or more rings 54 made of metal and one or more rings made of a non-metal. Also, while several rings 54 are shown for each of seal stack 50a, b, one or more rings may be used.

[0018] Referring to FIG. 3, in one non-limiting embodiment, the valve 10 may be used to create or diffuse a differential pressure between a fluid source in a subsurface environment and an environment in a well tool 100. The fluid source may be fluid in a borehole 102 or a fluid reservoir residing in a formation 108. The well tool 100 may be a bottomhole drilling assembly, a fluid sampling tool, a coring tool, or any other tool that is configured or performs one or more tasks (e.g. , forming the borehole, sampling / testing formation solids or fluids, etc.) in the borehole 102. A sample from the formation 108 may be retrieved using a packer-type probe 12 that engages a wall of the borehole 102 to isolates the fluid in the formation 108 from the borehole fluid 104. In other embodiments not shown, one or more annular packers may be used to isolate a zone in the borehole 102. The isolated borehole zone may fill with a formation fluid. In either case, the valve 10 may be used to convey a fluid sample retrieved from the isolated zone to a sample bottle 110 or other similar receptacle. The well tool 100 may be conveyed via a work string 106, which may include a rigid carrier (e.g. , drill string, casing, liner, etc.) or non-rigid carrier (e.g., wireline, slickline, e-line, etc.).

[0019] Referring now to FIGS. 1A and 3, in one mode of use, the well tool

100 may be conveyed into a borehole 102 to retrieve one or more fluid samples. After being appropriately positioned, a hydraulic source (not shown) pressurizes the pressure chamber 26a via the pilot inlet 28a with a hydraulic fluid to urge the mandrel 30 in an axial direction marked with arrow 44. This action sets the valve 10 in an open position and allows a retrieved fluid, which may be a liquid, a gas, or a mixture thereof, to flow to the fluid outlet 24 via the fluid inlet 22 and the passage 48. The retrieved fluid, or fluid "sample," may be collected in a sample receptacle 110. It should be appreciated that during the sampling activity, the valve 10 may be considered pressure balanced. That is, the fluid pressure at the fluid inlet 22 is applied to the seal 62 above and the seal 64 below the fluid inlet 22. This balanced pressure reduces the likelihood that the mandrel 30 will move due to pressure fluctuations.

[0020] To terminate the sampling operation, the hydraulic source (not shown) pressurizes the pressure chamber 26b via the pilot inlet 28b to urge the mandrel 30 in an axial direction marked with arrow 46, which sets the valve 10 in the closed position.

[0021] Referring now to FIGS. IB and 2, in the closed position, fluid pressure at the fluid inlet 22 generates a pressure differential across the seal 40. The differential between the pressure at the fluid source and the interior of the well tool 100 may approach twenty-five thousand PSI. This pressure compresses the seal 40 against the support 47. Specifically, the upper end adapter 48a compresses the spring stack 50a against the center adapter 52. The center adapter 52 communicates this pressure to the seal stack 50b. This compression causes the ring(s) 54 to expand and compress the tips 60 of the wings 56 to engage and seal against an adjacent surfaces 44, 46. It should be appreciated that an increase in pressure causes a corresponding increase in the sealing force at the contact between the wings 56 and the adjacent surfaces 44, 46. The resulting seal may be a gas-tight seal. Moreover, in instances where multiple seal rings 54 are used, multiple independent sealing contacts are formed. It should also be appreciated that this gas-tight seal is obtained without applying a sealing agent at the contacting surfaces (e.g. , grease).

[0022] It should be appreciated that when the seal 40 isolates an inflowing fluid sample from surrounding fluid during retrieval, the seal 40 prevents the inflowing fluid from leaking out of the passage 48. When preserving a retrieved fluid sample as the tool is being returned to the surface, the seal 40 prevents the fluid sample from leaking into the passage 48. Thus, the seal 40 has bidirectional sealing capability. However, it should be understood that if a separate seal is used to prevent either fluid leaking into or out of the passage 48, then the seal 40 does not need to be bidirectional and only one seal stack may be used.

[0023] Also, in certain embodiments, an actuator 75 may be used to allow pressurized fluid to escape or bleed from the pressure chamber 26b. The actuator 75 may be used to manually close the valve 10. For instance, if the valve 10 is in the open position shown in FIG. 1A, the actuator 75 may be partially or completely removed to allow hydraulic fluid to escape, which would allow the valve 10 to shift to the closed position in FIG. IB. In some embodiments, the actuator 75 may be a threaded body that is screwed into the housing 20.

[0024] While the foregoing disclosure is directed to the one mode embodiments of the disclosure, various modifications will be apparent to those skilled in the art. For example, while a hydraulic source is shown for moving the mandrel, an electric motor may also be used to translate the mandrel. Also, in certain embodiments, a unidirectional seal may be used to form an adequate seal. It is intended that all variations be embraced by the foregoing disclosure.