Pump rod clamp and blowout preventer

Claims

We claim:

1. A pump rod clamp for gripping a pump rod in an oil, gas or water well, the pump rod clamp comprising:

(i) a central housing having a longitudinal bore for receiving a pump rod;

(ii) a plurality of clamping members receivable within said central housing; and,

(iii) one or more actuators to cause said clamping members to be moved between an activated position where they grippingly engage the exterior surface of the pump rod and a deactivated position where they are released from contact with the exterior surface of the pump rod,

each of said clamping members having a leading face that includes one or more gripping inserts releasably secured thereto, said gripping inserts having outer faces that are arcuate in shape and that generally correspond to the curvature of the exterior or the pump rod, said outer faces of said gripping inserts generally aligned with the exterior surface of the pump rod and grippingly engaging the pump rod when said clamping members are in said activated position such that force exerted by each individual clamping member is concentrated and transmitted by said outer faces of said one or more gripping inserts to the pump rod.

2. The device as claimed in claim 1 wherein the combined surface area of said outer faces of said gripping inserts upon each individual clamping member is less than the surface area of the portion of said leading face of said individual clamping member adjacent to the pump rod.

3. The device as claimed in claim 1 wherein said central housing includes a pair of opposed radial bores generally perpendicular to said longitudinal bore and having interior ends terminating at said longitudinal bore, said pump rod clamp including two clamping members, each in the general form of a ram receivable within said radially opposed bores.

4. The device as claimed in claim 1 wherein said gripping inserts are formed from hardened steel.

5. The device as claimed in claim 1 wherein said outer faces of said gripping inserts have an arcuate shape generally corresponding to the curvature of the exterior of the pump rod.

6. The device as claimed in claim 5 wherein said outer faces of said gripping inserts include ridges or teeth to enhance the gripping of the pump rod.

7. The device as claimed in claim 5 wherein said outer faces of said gripping inserts are coated with a ceramic material, said ceramic material enhancing the ability of said gripping inserts to grippingly engage the pump rod and providing an electrically insulative barrier between said pump rod clamp and the pump rod when said clamping members are in said activated position.

8. The device as claimed in claim 1 including a pair of clamping members radially opposed to one another within said central housing, when in said activated position said clamping members sealingly engaging against the pump rod and one another to limit the escape of fluids from the well.

9. The device as claimed in claim 8 wherein said clamping members include an elastomeric seal upon their leading faces, said elastomeric seal providing a sealing engagement between said clamping members and the exterior surface of the pump rod, and between the respective leading faces of said radially opposed clamping members.

10. A pump rod clamp for gripping a pump rod in an oil, gas or water well, the pump rod clamp comprising:

(i) a central housing having a longitudinal bore for receiving a pump rod, said central housing including at least one pair of opposed radial bores generally perpendicular to said longitudinal bore and having interior ends terminating at said longitudinal bore;

(ii) a ram received within each of said opposed radial bores, each of said rams having a leading face generally directed toward the exterior surface of the pump rod; and,

(iii) one or more actuators to cause said rams to be moved within said opposed radial bores between an activated position where said rams grippingly engage the pump rod to limit rotational and axial movement thereof, and a deactivated position where said rams are disengaged from the pump rod,

each of said rams including one or more gripping inserts releasably securable to their leading faces such that when said rams are in said activated position said gripping inserts contact the exterior surface of the pump rod, said gripping inserts having outer faces with an arcuate shape generally corresponding to the curvature of the exterior of the pump rod and coated with a ceramic material, said ceramic material enhancing the ability of said gripping inserts to grippingly engage the pump rod and providing an electrically insulative barrier between said pump rod clamp and the pump rod when said clamping members are in said activated position.

11. The device as claimed in claim 10 wherein the combined surface area of said outer faces of said one or more gripping inserts on each individual ram is less than the surface area of the portion of the leading face of said individual ram adjacent to the pump rod such that force exerted by each individual ram against the exterior surface of the pump rod is concentrated and distributed over said smaller surface area of said one or more gripping inserts.

12. The device as claimed in claim 10 wherein said outer faces of said gripping inserts include horizontal, vertical, or horizontally inclined ridges or teeth.

13. The device as claimed in claim 10 wherein said leading faces of said rams include an elastomeric seal for sealingly engaging the exterior surface of the pump rod and for sealing engagement of the leading faces of opposed rams to limit the escape of fluids from the well.

14. A clamping blowout preventer for gripping a pump rod in an oil, gas or water well, the clamping blowout preventer comprising:

(i) a central housing having a longitudinally oriented bore for receiving a pump rod, said central housing including at least two radially opposed bores generally perpendicular to said longitudinal bore and having interior ends terminating at said longitudinal bore;

(ii) a ram received within each of said radially opposed bores, each of said rams having a leading face generally directed toward the exterior surface of the pump rod, said leading faces of said rams including one or more gripping inserts releasably secured thereto said gripping inserts having outer faces that are arcuate in shape and that generally correspond to the curvature of the exterior or the pump rod;

(iii) at least one actuator to cause said rams to be moved between an activated and deactivated position, when in said activated position said rams driven inwardly toward the pump rod causing said outer faces of said gripping inserts to grippingly engage the exterior surface of the pump rod and to limit axial and rotational movement thereof, when in said deactivated position said rams retracted from the pump rod permitting said gripping inserts to be released from engagement with the pump rod; and,

(iv) a seal secured to each of said rams such that the seals on opposed rams engage both the exterior surface of the pump rod and one another when said rams are in said activated position, to limit well fluids from escaping from the well.

15. The device as claimed in claim 14 wherein said outer faces of said gripping inserts of each individual ram have a combined surface area less than the surface area of the portion of said leading face of said individual ram adjacent to the pump rod such that force exerted by each individual ram against the exterior surface of the pump rod is concentrated and distributed over said smaller surface area of said one or more gripping inserts.

16. The device as claimed in claim 14 wherein said outer faces of said gripping inserts are coated with a ceramic material that enhances the engagement of said gripping inserts with the exterior surface of the pump rod and that presents an electrically insulative connection therebetween.

17. The device as claimed in claim 16 wherein said gripping inserts include horizontal, vertical or horizontally inclined ridges or teeth upon their outer faces.

18. The device as claimed in claim 14 wherein said seals are comprised of elastomers, said elastomers further providing seals between said rams and said radially opposed bores to limit the passing of well fluids therebetween.

19. The device as claimed in claim 14 wherein the leading face of each of said rams includes and arcuate channel thereon, said arcuate channel in general alignment with the pump rod, said gripping inserts releasably secured to said rams within said arcuate channel.

20. A pump rod clamp for gripping a pump rod in a oil, gas or water well, the pump rod clamp comprising:

(i) central housing having a longitudinal bore for receiving a pump rod;

(ii) a plurality of clamping members received within said central housing; and,

(iii) one or more actuators to cause said clamping members to be moved between an activated position where they grippingly engage the exterior surface of the pump rod and a deactivated position where they are released from contact with the exterior surface of the pump rod,

each of said clamping members comprising a ram received within a radial bore extending through said central housing generally perpendicular to said longitudinal bore and having an interior end terminating at said longitudinal bore, each of said rams having a leading face with an arcuate channel thereon for grippingly engaging the pump rod when said rams are in said activated position, said arcuate channel coated with a ceramic material to enhance the ability of said arcuate channel to grippingly engage the pump rod and to provide an electrically insulative barrier between said pump rod clamp and the pump rod when said rams are in said activated position.

FIELD OF THE INVENTION

This invention relates generally to a pump rod clamp and blowout preventer as may be used on oil, gas water wells, and in particular a new and improved pump rod clamp and blowout preventer having an enhanced polished rod clamping or gripping capability.

BACKGROUND OF THE INVENTION

The use of pump rod clamps and blowout preventers on oil, gas and water wells is a common occurrence. Pump rod clamps are used generally to hold the pump or polished rod and may take any one of a wide variety of forms ranging from a pair of rams that are driven radially inward in order to contact the pump rod and hold it in place, to wedges that may be inserted around the rod, to a pair of clamping members that may be bolted around the exterior surface of the rod and hung from a mandrel or other support member. Regardless of the particular structure of the clamp, its primary purpose is to either suspend the rod within the well, and/or to prevent rotational movement of the pump rod.

Blowout preventers (or BOP's as they are typically called) are critical pieces of equipment that are used to seal off the well and contain its contents under a variety of different situations. For example, during the servicing of a wellhead one or more blowout preventers are often used to seal against the pump or polished rod to contain the contents of the well when downstream equipment is removed or disassembled for servicing. In other instances blowout preventers may be used to seal off a well where the pump rod is removed, or in the event of a failure of the pump rod.

Blowout preventers that are used in producing oil and gas wells are most commonly comprised of a pair of rams that are received within cylinders or bores extending through a BOP housing and situated generally perpendicular to the longitudinal axis of the well casing. Typically the end of each ram has a semi-circular channel on its face to allow it to seal against the exterior surface of the polished rod when driven inwardly. The faces of the rams may include an elastomer or other sealing mechanism to ensure that a fluid tight seal is created when the rams fully engage the polished rod. Examples of such prior existing blowout preventers are described in U.S. Pat. Nos. 4,860,826, 5,746,249, and 5,875,841.

While currently available blowout preventers are generally effective in sealing around a polished rod and preventing the contents of a well from escaping, they nevertheless suffer from a number of inherent limitations. In order to ensure a tight seal between the rams and the polished rod, particularly where the well is a high pressure well or contains natural gas or hydrogen sulfide, operators have developed a tendency to drive the rams inwardly against the polished rod using a considerable amount of force. While doing so has the effect of compressing the elastomer against the rod and helping to ensure a good seal, in many cases the metal faces of the rams are also driven into contact with the exterior surface of the rod. In some cases rig hands intentionally drive the faces of the rams into the polished rod as a means to not only seal off the well, but to also effectively act as a rod clamp to hold the polished rod in place. Where the pump in question is a reciprocating pump, the rams may be used to maintain or hold the weight of the rod while work is performed upon components downstream of the BOP. Where the pump is a rotary style pump, the rams may be used to both hold the weight of the polished rod and to prevent rotation caused through backspin forces applied to the rotor of the pump by the head of fluid in the well. In either case, use of the BOP rams to not only seal the well but to grasp or clamp the rod can have the effect of marking or scoring the exterior surface of the rod and/or the face of the ram, neither of which is desirable. Further, when the metallic faces of the rams contact the exterior of the polished rod an electrical connection will be formed therebetween, which in some circumstances may also be undesirable.

Currently available polished rod clamps are also not without their limitations. Where the well is equipped with a separate polished rod clamp the overall height of the wellhead will be increased by the height of the clamp. Use of a dedicated rod clamp also results in an increase in equipment cost and represents a further mechanical component that may malfunction or fail. In addition, the use of a separate polished rod clamp does not prevent an operator from over tightening the BOP rams and causing their metal faces to score or damage the surface of the polished rod.

SUMMARY OF THE INVENTION

The invention therefore provides a pump rod clamp and blowout preventer that is in the form of a single component capable of both sealingly engaging a polished rod to prevent the escape of fluid from a well, while at the same time providing an enhanced ability to clamp or grip the rod and to prevent or retard axial and/or rotational movement. In one embodiment the invention further provides a mechanism by which the polished rod may be clamped and securely held without scoring or damaging the exterior surface of the rod, and without the formation of an electrical bonding between the invention and the pump rod.

Accordingly, in one of its aspects the invention provides a pump rod clamp for gripping a pump rod in an oil, gas or water well, the pump rod clamp comprising a central housing having a longitudinal bore for receiving a pump rod; a plurality of clamping members receivable within said central housing; and, one or more actuators to cause said clamping members to be moved between an activated position where they grippingly engage the exterior surface of the pump rod and a deactivated position where they are released from contact with the exterior surface of the pump rod, each of said clamping members having a leading face that includes one or more gripping inserts releasably secured thereto, said gripping inserts having outer faces generally aligned with the exterior surface of the pump rod and for grippingly engaging the pump rod when said clamping members are in said activated position such that force exerted by each individual clamping member against the pump rod is concentrated and distributed over said outer faces of said one or more gripping inserts of said individual clamping member.

In a further aspect the invention provides a pump rod clamp for gripping a pump rod in an oil, gas or water well, the pump rod clamp comprising a central housing having a longitudinal bore for receiving a pump rod, said central housing including at least one pair of opposed radial bores generally perpendicular to said longitudinal bore and having interior ends terminating at said longitudinal bore; a ram received within each of said opposed radial bores, each of said rams having a leading face generally directed toward the exterior surface of the pump rod; and, one or more actuators to cause said rams to be moved within said opposed radial bores between an activated position where said rams grippingly engage the pump rod to limit rotational and axial movement thereof, and a deactivated position where said rams are disengaged from the pump rod, each of said rams including one or more gripping inserts releasably securable to their leading faces such that when said rams are in said activated position said gripping inserts contact the exterior surface of the pump rod, said gripping inserts having outer faces with an arcuate shape generally corresponding to the curvature of the exterior of the pump rod and coated with a ceramic material, said ceramic material enhancing the ability of said gripping inserts to grippingly engage the pump rod and providing an electrically insulative barrier between said pump rod clamp and the pump rod when said clamping members are in said activated position.

The invention also concerns a clamping blowout preventer for gripping a pump rod in an oil, gas or water well, the clamping blowout preventer comprising a central housing having a longitudinally oriented bore for receiving a pump rod, said central housing including at least two radially opposed bores generally perpendicular to said longitudinal bore and having interior ends terminating at said longitudinal bore; a ram received within each of said radially opposed bores, each of said rams having a leading face generally directed toward the exterior surface of the pump rod, said leading faces of said rams including one or more gripping inserts releasably secured thereto; at least one actuator to cause said rams to be moved between an activated and deactivated position, when in said activated position said rams driven inwardly toward the pump rod causing said gripping inserts to grippingly engage the exterior surface of the pump rod and to limit axial and rotational movement thereof, when in said deactivated position said rams retracted from the pump rod permitting said gripping inserts to be released from engagement with the pump rod; and, a seal secured to each of said rams such that the seals on opposed rams engage both the exterior surface of the pump rod and one another when said rams are in said activated position, to limit well fluids from escaping from the well.

In yet a further aspect the invention provides a pump rod clamp for gripping a pump rod in a oil, gas or water well, the pump rod clamp comprising central housing having a longitudinal bore for receiving a pump rod; a plurality of clamping members received within said central housing; and, one or more actuators to cause said clamping members to be moved between an activa