Compact insert for variable bore ram packer in a ram type blowout preventer

Abstract

A variable bore ram packer designed for use in a standard ram-type blowout preventer used in oil and gas drilling operations is disclosed. The variable bore ram packer is molded of an elastomeric material having a central semi-circular opening sized to fit closely about a tubular member. The packer member includes a plurality of pillar inserts molded within the elastomeric material around the central semi-circular opening. The packer member and the plurality of pillar inserts are molded into a unitary structure allowing the plurality of pillar inserts to move and seat against different diameter tubular members to prevent extrusion of the elastomeric material between the pillar inserts and the tubular member. The pillar inserts include a top plate, a bottom plate and a reduced cross section central column integrally formed therebetween. The reduced cross section central column allows a rubber with higher moduli to be used.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to an improvement in variable bore ram packers for a ram-type blowout preventer used in oil and gas drilling operations. The improved ram packer is designed to reduce the overall stiffness of the packer, thereby allowing it to be more elastic and to better seal on the contours of the drill pipe disposed within the bore of the blowout preventer. This configuration allows the use of rubber having higher moduli which is desirable in high temperature well conditions. Ram-type blowout preventers are part of a pressure control system used in oil and gas drilling operations to control unexpected well bore pressure spikes or “kicks” as they are commonly referred to in the industry.

[0003] The blowout preventer has a body with a vertical bore and a pair of laterally disposed opposing bonnet assemblies. Each bonnet assembly includes a piston which is laterally moveable within the bonnet assembly by pressurized hydraulic fluid. Replaceable sealing elements called “packers” are mounted within rams attached to the ends of the pistons which extend into the blowout preventer bore. When these pistons are moved to a closed position, commonly referred to as “closing the blowout preventer” or “closing the rams”, the vertical bore of the blowout preventer is sealed and the kick is contained. These packers are available in a variety of configurations designed to seal the blowout preventer bore when the opposing rams and pistons are moved to their closed position.

[0004] One type of ram with packer has ends designed to seal around pipe of a specific size in the blowout preventer bore when the blowout preventer is closed. Other rams with packers are configured to seal around a range of pipe sizes. It is the type designed to seal around a range of pipe sizes, called variable bore ram packers to which the present invention is directed. The ram packers form a pressure tight seal during a kick until the well bore pressure can be controlled. The well bore pressure can reach several thousand pounds per square inch during a kick. Each ram packer has a semicircular opening in its front face to form a seal around 180° of the outer periphery of the pipe. When the rams are closed as described above, the opposing ram packers meet and seal the entire 360° periphery of the pipe. The novel variable bore ram packer of the present invention is designed to reduce the stress in the rubber by utilizing a reduced cross section metal insert.

[0005] In an effort to minimize the tearing and loss of mass of the elastomeric sealing element, numerous modifications and additions to the ram packer and particularly the elastomeric sealing element in ram-type blowout preventers have been used. The variable bore ram packer of the current invention offers a substantial improvement by offering a variable bore ram packer with increased elasticity which improves the service life of the packer and reduces the forces needed to operate the variable bore packer.

[0006] 2. Description of Related Art

[0007] The use of metal inserts in a conical-type blowout preventer is disclosed in U.S. Pat. No. 2,846,178 to B. S. Minor.

[0008] U.S. Pat. No. 3,897,038 to R. K. Le Rouax shows a ram type blowout preventer using metal inserts as an anti-extrusion means.

[0009] The use of metal inserts in an annular blowout preventer to control the stress level in the elastomeric packer unit is shown in U.S. Pat. No. 3,917,293 to G. E. Lewis et al.

[0010] U.S. Pat. No. 4,099,699 to H. Allen shows the use of irising metal inserts in an annular blowout preventer.

[0011] Another example of metal inserts in a variable bore blowout preventer in disclosed in U.S. Pat. No. 4,229,012 to B. C. Williams, III.

[0012] U.S. Pat. No. 4,444,404 to G. C. Parks, Jr. shows an example of a variable bore ram packer with interlocking anti-extrusion metal inserts.

[0013] Another example of a variable bore ram packer with interlocking anti-extrusion metal inserts is disclosed in U.S. Pat. No. 4,458,876 to G. R. Schaeper et al.

[0014] U.S. Pat. No. 4,550,895 to D. U. Shaffer shows an early version of a variable bore ram packer. This apparatus utilizes a plurality of annular segments embedded in the elastomeric rubber to aid in effectuating a seal.

SUMMARY OF THE INVENTION

[0015] The variable bore ram packer of the present invention is designed for use in a standard ram-type blowout preventer used in oil and gas drilling operations. The blowout preventer has a body with an axial bore, a pair of opposing bonnet assemblies and a pair of opposing rams laterally moveable within the bonnet assemblies by a pressurized fluid source to control flow of well fluids through the blowout preventer body axial bore. The variable bore ram packer includes a ram body, a top seal and a packer member. The packer member is molded of an elastomeric material having a central semi-circular opening sized to fit closely about a tubular member. The packer member includes a plurality of pillar inserts molded within the elastomeric material around the central semicircular opening. The packer member and the plurality of pillar inserts are molded into a unitary structure allowing the plurality of pillar inserts to move and seat against different diameter tubular members to prevent extrusion of the elastomeric material between the pillar inserts and the tubular member.

[0016] The pillar inserts include a top plate, a bottom plate and a reduced cross section rectangular column positioned therebetween and integrally formed therewith. The top and bottom plates are a substantially triangular shape and each of the top and bottom plates includes a guide lip and a guide shoulder. The guide lips and guide shoulders of adjacent top plates and the guide lips and guide shoulders of adjacent bottom plates coact to provide an irising motion to the top and bottom plates as the top and bottom plates move and seat against different diameter tubular members. The simultaneous movement of the top and bottom plates of the insert allows the top and bottom plates to move and seat against the tubular member.

[0017] A principal object of the present invention is to provide a variable bore ram packer that allows sealing over a wide range of tubular member diameters that minimizes the force required to operate the variable bore ram packer.

[0018] Another object of the present invention is to provide a variable bore ram packer that will reliably maintain a seal against different sized tubular members while minimizing damage to the elastomeric sealing element of the packer.

[0019] A final object of the present invention is to provide a variable bore ram packer that can utilize a rubber compound with higher moduli of elasticity to seat and seal around tubular members within a designated size range.

[0020] These with other objects and advantages of the present invention are pointed out with specificness in the claims annexed hereto and form a part of this disclosure. A full and complete understanding of the invention may be had by reference to the accompanying drawings and description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] These and other objects and advantages of the present invention are set forth below and further made clear by reference to the drawings, wherein:

[0022] FIG. 1 is a perspective view with a cutaway section of the variable bore ram packer of the present invention installed in a typical ram-type blowout preventer used in oil and gas drilling operations.

[0023] FIG. 2 is a perspective view of the variable bore ram packer of the present invention in an exploded view.

[0024] FIG. 3 is a perspective view of the pillar insert for the variable bore ram packer.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0025] With reference to the drawings, and particularly to FIG. 1, an isometric view of a ram type blowout preventer 10 used in oil and gas drilling operations is shown. The ram type blowout preventer 10 includes a body or housing 12 with a vertical bore 14 and laterally disposed ram guideways 16. Bonnet assemblies 18 are mounted to the body 12 with suitable securing means such as studs or bolts 20 and aligned with laterally disposed guideways 16. Each bonnet assembly 18 includes an actuation means 22, including a piston 24 and connecting rod 26. While only one guideway 16 and actuation means 22 is shown, it is understood by those of ordinary skill in the art that there is a pair of opposed guideways 16 and actuation means 22. Each connecting rod 26 is connected to a ram 28 which includes the variable bore ram packer 30 of the present invention. Actuation means 22 allows ram 28 and variable bore ram packer 30 to be reciprocated within guideways 16 or “opening and closing the rams” as it is referred to in the industry.

[0026] Variable bore ram packer 30 is shown in an exploded view in FIG. 2 to aid in understanding the relationship between the parts. Variable bore ram packer 30 includes packer member 32 of an elastomeric material with suitable rheological characteristics and pillar inserts 34 molded into one unitary structure with pillar inserts 34 arranged around a central semi-circular opening 36 to form an insert array 38 that is sized to fit closely about a tubular member. Packer pins 40 are molded into variable bore ram packer 30 for connecting variable bore ram packer 30 to ram 28. Packer member 32 is molded to form side packers 42 on its lateral edges. Ram 28 includes top seal 44 on its upper face. Top seal 44 and side packers 42 combine to seal ram 28 in guideways 16 of ram type blowout preventer 10 in a manner well known to those of ordinary skill in the art. When rams 28 are closed around a tubular member disposed in bore 14 of ram type blowout preventer 10, packer members 32 seal around the tubular member in a manner to be described more fully hereinafter.

[0027] As seen in exploded view in FIG. 2 and in an enlarged view in FIG. 3, pillar inserts 34 include top plate 46, bottom plate 48 and central column 50. Top plate 46 and bottom plate 48 are substantially triangular in shape with central column 50 positioned thereon. Central column 50 is integrally formed with top plate 46 and bottom plate 48 by suitable means as casting. Other means of forming pillar insert 34 such as attaching central column 50 to top plate 46 and bottom plate 48 by welding are envisioned and within the scope of the present invention. Central column 50 is shown having a rectangular cross section but differently shaped cross sections would be suitable provided they give sufficient bending strength to pillar insert 34. Central column 50 is sized to have a relatively small cross section to allow the elastomeric material of packer member 32 to more easily move around central column 50 as packer 30 is moved from its open to closed positions. This results in a substantial reduction in the overall stiffness of packer member 32. Therefore, packer member 32 and insert array 38 a greater elasticity or flexibility even though rubber having higher moduli of elasticity may be used. This allows packer member 32 and insert array 38 to move with greater ease and more readily seal against a tubular member in bore 14. Additionally, the increased flexibility of packer member 32 and insert array 38 aids in allowing an increased diameter range for the tubular members to be sealed against.

[0028] Top plate 46 and bottom plate 48 are mirror images of one another and include guide lip 52 and guide shoulder 54 formed on top plate 46 and guide lip 56 and guide shoulder 58 formed on bottom plate 48. Thus, when pillar inserts 34 are molded into packer member 32, guide lips 52 and guide shoulders 54 of adjacent top plates 46 overlap. Similarly, guide lips 56 and guide shoulders 58 of adjacent bottom plates 48 overlap. Thus, as seen in FIG. 2, the assemblies of top plates 46 and bottom plates 48 are arranged to form semi-circular steel arcs similar to that of an “iris” shutter of a camera that acts to prevent extrusion of the elastomeric material of packer member 32 in use.

[0029] The movement and actual irising motion of the insert array 38 is well known to those of skill in art and will be only briefly described here. With drill pipe or similar tubular member positioned within the bore 14 of ram type blowout preventer 10 actuation means 22 is operated to move variable bore ram packer 30 to the closed or sealing position. In this position, pillar inserts 34 along with packer member 32 have moved inward. Top plates 46 and bottom plates 48 have moved spirally inward like the iris of a camera shutter to form a continuous band of steel around the drill pipe in bore 14. As pillar inserts 34 move inwardly in an irising motion, guide lips 52 and guide shoulders 54 of adjacent top plates 46 and guide lips 56 and guide shoulders 58 formed on bottom plates 48 also slide over one another to insure proper movement. The relatively small cross section of central column 50 serves to reduce the stress in the elastomeric material or rubber of packer member 32 as it is forced radially inward to seal against the tubular member. This reduced cross section allows the use of rubber with higher moduli of elasticity as previously discussed.

[0030] The construction of our improved variable bore ram packer will be readily understood from the foregoing description and it will be seen that we have provided an improved variable bore ram packer to allow sealing on tubular members within a predetermined range while reducing stresses in the elastomeric rubber compound. Furthermore, while the invention has been shown and described with respect to certain preferred embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of the specification. The present invention includes all such equivalent alterations and modifications, and is limited only by the scope of the appended claims.

Claims

1. A variable bore packer used in a ram-type blowout preventer for oil and gas drilling operations, comprising:

a packer member molded of elastomeric material having a central semi-circular opening sized to fit closely about a tubular member;

a plurality of pillar inserts molded within said elastomeric material around said central semi-circular opening to form an insert array;

said packer member and said insert array being molded into a unitary structure allowing said insert array to move and seat against different diameter tubular members to prevent extrusion of said elastomeric material between said pillar inserts and the tubular member;

said unitary structure is molded to form a pair of side packers integral with said packer member;

said pillar inserts include a top plate, a bottom plate and a central column positioned therebetween; and,

said central column is sized to allow a substantial reduction in the stiffness of the packer member and insert array when said elastomeric material is a higher modulus rubber.

2. A variable bore packer used in a ram-type blowout preventer for oil and gas drilling operations according to claim 1, wherein:

said central column has a rectangular cross section.

3. A variable bore packer used in a ram-type blowout preventer for oil and gas drilling operations according to claim 2, wherein:

said top plate, said bottom plate and said central column are integrally formed.

4. A variable bore packer used in a ram-type blowout preventer for oil and gas drilling operations according to claim 3, wherein:

each of said top and bottom plates includes a guide lip and a guide shoulder; and,

said plurality of pillar inserts coact to provide an irising motion to move and seat against different diameter tubular members.

5. A variable bore packer used in a ram-type blowout preventer for oil and gas drilling operations according to claim 4, including:

a plurality of packer pins molded in said packer member to connect said variable bore packer to a ram-type blowout preventer.

6. A ram-type blowout preventer used in oil and gas drilling operations having a variable bore ram assembly, comprising:

a body with a vertical bore;

a pair of opposing bonnet assemblies laterally disposed in said body;

a pair of opposing variable bore rams laterally moveable within said bonnet assemblies;

said variable bore rams providing a seal around a tubular member having a diameter within a predetermined range, said tubular member disposed within said vertical bore upon closing of said variable bore rams;

said pair of variable bore rams each includes a ram body, a top seal and a packer member;

said packer member molded of elastomeric material having a central semi-circular opening sized to fit closely about a tubular member;

said packer member includes a plurality of pillar inserts molded within said elastomeric material around said central semi-circular opening to form an insert array;

said packer member and said plurality of pillar inserts being molded into a unitary structure allowing said insert array to move and seat against different diameter tubular members to prevent extrusion of said elastomeric material between said pillar inserts and the tubular member;

said unitary structure is molded to form a pair of side packer seals integral with said packer member;

said pillar inserts include a top plate, a bottom plate and a central column positioned therebetween; and,

said central column is sized to allow a substantial reduction in the stiffness of the packer member and insert array when said elastomeric material is a higher modulus rubber.

7. A ram-type blowout preventer used in oil and gas drilling operations having a variable bore ram assembly according to claim 6, wherein:

said central column has a rectangular cross section.

8. A ram-type blowout preventer used in oil and gas drilling operations having a variable bore ram assembly according to claim 7, wherein:

said top plate, said bottom plate and said central column are integrally formed.

9. A ram-type blowout preventer used in oil and gas drilling operations having a variable bore ram assembly according to claim 8, wherein:

each of said top and bottom plates includes a guide lip and a guide shoulder; and,

said plurality of pillar inserts coact to provide an irising motion to move and seat against different diameter tubular members.

10. A ram-type blowout preventer used in oil and gas drilling operations having a variable bore ram assembly according to claim 9, including:

a plurality of packer pins molded in said packer member to connect said variable bore packer to a ram-type blowout preventer.