High velocity and pressure BOP ram seal, ram body, and ram seal assembly

A polished rod blowout preventer (BOP) ram seal is created by installing a rubber seal component onto a movable metal ram block that allows the ram to be opened and closed. The rubber seal is installed into a corresponding groove on the metal ram block or body that allows for compression of the seal between the polished rod, BOP ram housing, and ram bodies. The anti-extrusion features allow for use in high velocity and high-pressure applications. A blind seal embodiment is also disclosed.

BACKGROUND

Polished rod blow out preventers (rod BOPs) are a common piece of equipment that have been used for years to seal off wells when the fluids are not at the planned operational conditions. As oil wells have evolved due to the changing operational conditions, so to have the BOPs needed to change.

The current method of sealing a well consists of a combination of a rubber seal material and a rigid metal body. These designs either involve molding the rubber entirely around the metal body or into a groove on the face and around the outside of the metal body. Previously as the rubber seal component would wear due to extended use, the entire ram assembly would be discarded and replaced. However, due to new environmental and economic concerns, the need for a replaceable rubber seal has developed.

New oil extraction methods are also causing a change in the conditions these BOPs have historically seen. From a combination of hydraulic fracturing and horizontal drilling, existing oil wells can see increased oil pressure that they were not initially designed to handle.

With the need for a replaceable seal and new oil extraction methods arose new problem, as rams were closed the annulus between the polished rod and BOP body would decrease. The decrease in the area causes and increase in the velocity of the fluid as it continues to flow at high pressure. This combination of high velocity and high pressure often would cause the seals to be ripped out of the groove on the metal block. Examples of known seals and ram seal assemblies that seek to address these concerns are disclosed in in U.S. Pat. No. 10,221,646 and Canadian Patent No. 2,716,430. These prior seals and ram seal assemblies have been found to be sub-optimal and a need has been identified for a new and improved seal, ram seal assembly, and ram body for receiving a seal that overcome deficiencies with known designs while providing better overall results.

SUMMARY OF THE PRESENT DEVELOPMENT

In accordance with one aspect of the present development, a blowout preventer ram seal includes a first section including a curved region with opposite first and second ends and a central portion that extends between and interconnects the first and second ends. A second section extends between and interconnects the first and second ends of the first section such that a seal opening is defined between the first section and second section. The second section includes a sealing region comprising a sealing region thickness. A central retention boss is connected to the sealing region and projects into the seal opening toward the first seal section. The central retention boss includes a retention boss thickness that is greater than the sealing region thickness such that the central retention boss is enlarged relative to the sealing region. First and second lateral retention bosses are respectively connected to the first and second opposite ends of the first seal section. The first and second lateral retention bosses extend outward from one side of the first seal section such that both of the first and second lateral retention bosses extend outwardly from the first seal section in the same direction and are arranged parallel and spaced-apart from each other.

In accordance with another aspect of the present development, a ram seal assembly for a blowout preventer includes a metal ram body including a cylindrical outer surface and opposite inner and outer faces. The outer face includes a ram shaft coupling structure adapted to be connected to an associated ram shaft. The ram body further includes a continuous outwardly opening seal-receiving groove that extends along the ram body. The groove comprising a first section including first and second ends located respectively on first and second lateral sides of the ram body, a second section that extends across the inner face of said ram body between the first and second ends of said first section, a third section connected to the second section, and first and second lateral boss recesses located on the opposite lateral sides of the ram body. An elastomeric ram seal is located in the seal-receiving groove. The seal includes a first seal section comprising a curved region including opposite first and second ends and a central portion that extends between and interconnects the first and second ends. A second seal section extends between and interconnects the first and second ends of the first seal section such that a seal opening is defined between the first seal section and second seal section. The second seal section includes a sealing region comprising a sealing region thickness. A central retention boss is connected to the sealing region and that projects into the seal opening toward the first seal section. The central retention boss includes a retention boss thickness that is greater than the sealing region thickness such that the central retention boss is enlarged relative to the sealing region. First and second lateral retention bosses are respectively connected to the first and second opposite ends of the first seal section. The first and second lateral retention bosses extends perpendicularly outward from one side of the first seal section such that both of the first and second lateral retention bosses extend outwardly from the first seal section in the same direction and are arranged parallel and spaced-apart from each other. The first seal section is seated in the first groove section, the second seal section is seated in the second groove section, the central retention boss is seated in the third groove section, and the first and second lateral retention bosses are respectively seated in the first and second lateral boss recesses.

DETAILED DESCRIPTION OF THE PRESENT DEVELOPMENT

A first aspect of the present development relates to a blowout preventer (BOP) ram seal S as shown inFIGS.1A-1C. In addition to the seal S, itself, the present development comprises a metal ram body RB (shown by itself inFIGS.2A-2E) onto which the seal S can be operatively installed as shown inFIGS.3A-3Dto form a ram seal assembly RSA in accordance with an embodiment of the present development. The ram seal assembly RSA for the BOP is comprised of two components, the rubber seal S and the metal ram body RB.

The seal S and ram body RB can each be made from a variety of conventional materials and manufacturing techniques without departing from the scope and intent of the invention. In one embodiment, the seal S comprises a one-piece molded polymeric structure such as a one-piece elastomeric structure comprising nitrile rubber, a fluorinated, carbon-based synthetic rubber (fluoroelastomer) such as FKM, or another suitable elastomeric compound or blend thereof. In one embodiment, the seal is injection molded but it can be formed using any other suitable process. The ram body RB can be a one-piece or structure comprising a metal such as high-grade carbon steel or high-grade stainless steel or another suitable metal. Other materials and structures can be used as are generally known in the art.

Referring particularly toFIGS.1A-1C, the seal S comprises a one-piece elastomeric seal body SB including a central seal opening SO. The seal body SB comprises four main sections or regions or portions that work in combination to minimize the amount of displacement or movement of the seal S relative to the ram body RB during use.

The one-piece elastomeric seal body SB comprises a first portion or first section S1comprising a curved (e.g., semi-circular) central region or portion S1cwith opposite first and second ends S1a, S1bthat are arranged parallel to each other. The curved central portion S1cextends between and interconnects the opposite first and second ends S1a, S1b. The first section S1comprises a mid-point S1dlocated on the curved central portion S1chalfway between the opposite first and second ends S1a, S1bwhich is the deepest point of the curved portion S1c. The first section S1is shown with a circular cross-section such that it comprises a cylindrical outer surface S1e. The first section S1defines a substantial part of the periphery such as at least a majority of the periphery (e.g., >50%) of the seal opening SO.

The seal body SB further comprises a second, inner section S2that extends between and interconnects the opposite first and second ends S1a, S1bof the first section S1to complete the periphery of the seal opening SO such that the first and second sections S1,S2cooperate to define the seal opening SO and its periphery, i.e., the periphery of the seal opening SO is defined by the first and second seal sections S1,S2. The second section S2lies in the same plane as the first section S1and comprises opposite first and second ends S2a, S2bthat are connected respectively to the first and second ends S1a, S1bof the first section S1. The first and second ends S2a, S2bof the second section S2are coaxially aligned along a second section axis S2X that extends between the opposite first and second ends S1a, S1bof the first section S1.

Between its opposite first and second ends S2a, S2b, the second section S2defines an enlarged seal region or sealing region SR that, in the illustrated embodiment, comprises a semi-circular seal recess RC with a circular radiused inside surface that is adapted and configured to sealingly engage the outer cylindrical surface of an associated polished rod or other cylindrical rod or member of an associated oil or gas well. In the illustrated embodiment, the seal recess RC is semi-circular and extends through an arc of or comprising 180 degrees as it extends between and interconnects the opposite first and second ends S2a, S2bof the second section S2. The arcuate seal recess RC is terminated at it opposite first and second ends RC1, RC2by first and second seal (or sealing) faces RC1f, RC2fthat can be planar as shown or otherwise conformed and adapted to mate in a fluid tight manner with corresponding seal faces RC2f, RC1fof a second identical seal S of an adjacent second ram seal assembly RSA of a pair of ram seal assemblies RSA such as the first and second ram seal assemblies RSA1, RSA2as described in further detail below and shown inFIG.7. In the illustrated embodiment, the seal region SR in which the seal recess RC is located comprises first and second parallel, spaced-apart side walls SRa, SRb and an end wall SRc that extends between and interconnects the first and second side walls SRa, SRb. As shown inFIG.1B, the sealing region SR further comprises opposite parallel upper and lower faces SRd, SRe and a maximum thickness T1of the sealing region SR (i.e., a sealing region thickness T1) is defined between the upper and lower faces SRd, SRe.

The seal body SB further comprises a bulbous central retention boss S3that is connected to and that projects from the end wall SRc of the seal region SR of the second section S2opposite the seal recess RC outwardly or rearwardly into the seal opening SO away from the seal recess RC toward the mid-point S1dof the first seal section S1. The central retention boss S3is aligned with the seal recess RC but on the opposite side of the second section S2as compared to the seal recess RC. In the illustrated embodiment, the retention boss S3comprises a partially cylindrical cross-section and partially cylindrical outer surface S3a(where “partially cylindrical” means a radiused cross-section or radiused outer surface that extends for less than 360 degrees about its center), and the central retention boss S3is bulbous or enlarged relative to the adjacent connecting part or neck S3C of the second section S2by which the retention boss S3is attached to the second section S2. As shown, the central retention boss S3comprises a maximum thickness or outside diameter OD (FIG.1B) that is greater than the maximum thickness T1of the sealing region SR when both are measured along an axis parallel to the central axis OX of the seal opening SO such that the central retention boss S3is bulbously enlarged relative to the seal region SR of the second section S2. The retention boss S3extends axially toward and away from the first and second opposite ends S1a, S1bof the seal first section S1along an axis that is parallel to the second axis S2xand defines a partially cylindrical body that is centrally and symmetrically located relative to the seal recess RC such that a center of the retention boss S3is aligned with the midpoint Std (the deepest point) of the seal recess RC and such that the retention boss S3extends laterally outward from its center in opposite first and second directions respectively toward the first and second ends S1a, S1bof the first seal section. The central retention boss S3thus defines an axial length L (FIG.1A) along which its outer partially cylindrical surface S3aextends. Furthermore, the retention boss S3is connected to the seal region SR by the connecting portion or neck S3C of the second section S2that preferably also extends coextensively with the retention boss S3for at least the axial length L. Those of ordinary skill in the art will recognize that the axially length L of the central retention boss S3and its connecting region S3C overlaps or coincides with an axial length RL (FIG.1b) of the deepest or innermost region of the seal recess RC such that the central retention boss S3effectively retains and minimizes movement or extrusion of the seal recess RC in its operative position during use.

The seal body SB further comprises first and second lateral retention bosses S4a, S4bthat are respectively connected to the first and second opposite ends S1a, S1bof the first seal section S1. These lateral retention bosses S4a, S4bextend perpendicularly outward from one side of the first seal section S1in the same direction with respect to each other such that the lateral retention bosses S4a, S4bare arranged parallel and spaced-apart relative to each other. The first and second lateral retention bosses S4a, S4bare thus arranged to extend perpendicularly outward from the plane in which the first and second seal sections S1,S2and the seal retention boss S3are located.

The metal ram body RB is dimensioned and conformed for operative securement of the seal S thereto to define the ram seal assembly RSA. The seal S is removable from the ram body RB by manual operation for installation and repair or replacement, but the seal S is designed to resist movement or “extrusion” during use so that it remains connected to the ram body RB in its operative position as shown inFIGS.3A-3D.

Shown by itself inFIGS.2A-2E, the ram body RB is generally cylindrical in shape and comprises a cylindrical outer surface RB1. The ram body RB comprises opposite inner and outer faces F1, F2that can be planar and parallel with respect to each other. The inner face F1comprises a semi-circular or semi-cylindrical body recess BR centered on a longitudinal axis LX (FIG.7) to closely receive the outer cylindrical surface of a polished rod or other cylindrical member PR. The outer face F2includes a ram shaft coupling structure F2C that is adapted to be connected to a ram shaft (not shown) that moves the ram body RB.

A continuous outwardly opening seal-receiving groove G extends along the ram body RB and is adapted and configured for operative installation and securement of the seal S. The groove G comprises a first section G1adapted to receive and retain the first section S1of the seal. The first groove section G1extends from a first end G1alocated on a first lateral side of the ram body RB across the ram body outer surface RB1to a second end G1blocated on a second lateral side of the ram body RB.

The groove G further comprises a second section G2adapted to receive and retain the second section S2of the seal S. The second section G2of the groove extends across the inner face F1and includes opposite first and second ends G2a, G2bthat connect respectively to the first and second ends G1a, G1bof the first groove section G1. The second groove section G2includes a portion Glc that extends through the semi-cylindrical body recess BR to receive the sealing region SR of seal S so that the seal recess RC is aligned with the body recess BR and positioned to engage the cylindrical outer surface of a polished rod or other cylindrical member located in the body recess BR as shown inFIG.7.

The groove G further comprises a third, central boss receiving section G3connected to the second section G2that is adapted to receive and retain the retention boss S3of the seal S. As best seen inFIG.2Dand alsoFIG.3C, the third section G3of the groove G comprises an inner portion or inner region G3awith a partially cylindrical cross section that is dimensioned and conformed to closely receive and retain the seal central retention boss S3with a close, resilient snap fit such that the central retention boss S3is resiliently captured in the inner region G3aof the third groove section G3. An outer portion or outer region G3bof the third groove section G3is reduced in height as compared to the inner semi-cylindrical section G3aso that the retention boss S3must be compressed and forced therethrough into the inner section G3ato achieve the noted snap-fit engagement of the retention boss S3in the inner section G3a. The outer portion G3bclosely accommodates the thickness T1of the seal region SR. The neck S3cof the seal S that connects the retention boss S3to the end wall SRc is located in the outer portion G3bof the third groove section G3. The outer portion G3bof the third groove section G3is connected to the second groove section G2, and the third groove section G3is preferably located midway between the opposite first and second ends G2a, G2bof the second groove section G2.

The groove G further comprises first (left) and second (right) lateral boss recesses G4aand G4bthat are located on opposite lateral sides of the ram body RB. The first lateral boss recess G4ais located at the intersection of the first end G1aof the first groove section G1and the first end G2aof the second groove section G2. Likewise, the second lateral boss recess G4ais located at the intersection of the second end G1bof the first groove section G1and the second end G2bof the second groove section G2. The first and second lateral boss recesses G4a, G4bare adapted to closely receive and retain the lateral retention bosses S4a, S4bof the seal S, respectively, as shown inFIGS.3A &3D.

As shown inFIG.7, those of ordinary skill in the art will recognize that a blowout preventer BOP will comprises a pair of like ram seal assemblies RSA (RSA1,RSA2) as shown herein that are adapted to cooperate with each other to sealingly engage the entire cylindrical outer surface of polished rod PR or other cylindrical member of an associated oil or gas well installation when the pair of ram seal assemblies RSA1,RSA2are moved toward each other so that the respective seals S thereof sealingly engage the cylindrical outer surface polished rod PR. In such case, the respective seal recesses RC closely surround and seal against the outer cylindrical surface of the polished rod PR and the seal faces RC1f, RC2fof one seal S engage the opposite corresponding seal faces RC2f, RC1fof the other seal S to define a 360-degree sealing interface around the polished rod PR.

In an alternative embodiment, the ram seal assemblies RSA are configured as blind ram seal assemblies as shown at RSA′ inFIG.4A-4D, which correspond respectively toFIGS.3A-3D. In such case, the blind ram seal assemblies RSA′ are adapted to sealingly engage each other when no polished rod or other cylindrical pipe or rod is present as shown inFIG.8and described below. The ram seal assembly RSA′ comprises a blind ram seal S′ shown by itself inFIGS.5A-5Cwhich correspond respectively toFIGS.1A-1C. The ram seal assembly RSA′ also comprises a blind ram body RB′ shown by itself inFIGS.6A-6Ewhich correspond respectively toFIGS.2A-2E(except thatFIG.6Ais a section view). Like components of the ram seal assembly RSA′ relative to the ram seal assembly RSA are shown with like reference characters that include a primed (′) designation. Similarly, like components of the seal S′ relative to the seal S are shown with like reference characters that include a primed (′) designation. Like components of the ram body RB′ relative to the ram body RB are shown with like reference characters that include a primed (′) designation.

Unlike the seal S, the second section S2′ of the blind ram seal S′ comprises a straight sealing region SR′ that comprises a flat seal face SRF′ in the illustrated embodiment. The seal face SRF′ can alternatively comprise curved or angled regions instead of a planar or flat face. The central, semi-cylindrical central retention boss S3′ of the seal S′ is aligned with and extends for a length L′ along the straight sealing region SR′ on the rear side, opposite the flat seal face SFR′ such that the central retention boss S3′ overlaps or is axially coextensive with the straight sealing region SR′ for a length RL′. Correspondingly, the inner face F1′ of the ram body RB′ is flat and omits the recess BR of the ram body RB. The second groove section G2′ of the ram body RB′ extends straight across the inner face F1′.

As shown inFIG.8, when first and second ram seal assemblies RSA′ (RSA1′, RSA2′) are abutted to obtain a blind seal, the respective straight sealing regions SR′ (and the flat or otherwise correspondingly shaped seal faces SRF′ thereof) are mated and sealingly engaged to provide the required seal.

Accordingly, those of ordinary skill in the art will recognize that a ram seal S, S′ provided in accordance with the present development can comprise at least one seal face such as the seal face SRF′ of the seal S′, or the first and second seal faces RC1f, RC2fof the seal S.