Blowout preventer ram assembly and method of using same

The techniques herein relate to a ram assembly for a blowout preventer for receiving a tubular of a wellbore. The ram assembly includes a ram block for engagement with the tubular, a ram shaft for selectively extending and retracting the ram block, and a ram connector for operatively connecting the ram shaft to the ram block. The ram block has at least one block groove. The ram shaft has a ram head with at least one shaft groove. The ram connector includes at least one shear connector correspondingly disposable in the block groove and the shaft groove whereby the ram shaft is releasably securable to the ram block.

BACKGROUND

This disclosure relates generally to techniques for performing wellsite operations. More specifically, the present invention relates to techniques, such as blowout preventers (BOPs) and related devices, for controlling leaks at a wellsite.

2. Background of the Related Art

Oilfield operations are typically performed to locate and gather valuable downhole fluids. Oil rigs may be positioned at wellsites, and downhole tools, such as drilling tools, may be deployed into the ground to reach subsurface reservoirs. Once the downhole tools form a wellbore to reach a desired reservoir, casings may be cemented into place within the wellbore, and the wellbore completed to initiate production of fluids from the reservoir. Casing, pipes or other tubing may be positioned in the wellbore to enable the passage of subsurface fluids to the surface. During wellsite operations a blowout preventer (BOP) may be placed at a wellhead to control pressure from the wellbore.

Leakage of subsurface fluids may pose a threat if released from the wellbore. Equipment, such as a BOP, may be positioned about the wellbore to form a seal with and/or sever pipes therein to prevent leakage of fluid as it is brought to the surface. In some cases, the BOPs employ rams and/or ram blocks that seal and/or sever tubing from the wellbore. Some examples of ram BOPs and/or ram blocks are provided in U.S. patent application Ser. No. 12/838,701, U.S. Pat. Nos. 4,647,002, 6,173,770, 5,025,708, 7,051,989, 5,575,452, 6,374,925, 2008/0265188, 5,735,502, 5,897,094, 7,234,530 and 2009/0056132. Some BOPs have bonnets as described, for example, in U.S. Pat. Nos. 5,897,094 and 7,044,430.

Despite the development of techniques relating to rams and/or ram blocks, there remains a need to provide advanced blowout preventer techniques. The present invention is directed to fulfilling these needs in the art.

SUMMARY

In at least one aspect, the disclosure relates to a ram assembly for a blowout preventer for receiving a tubular of a wellbore. The ram assembly has a ram block therein for engagement with the tubular, a ram shaft for selectively extending and retracting the ram block and a ram connector for operatively connecting the ram shaft to the ram block. The ram block has at least one block groove. The ram shaft has a ram head with at least one shaft groove. The ram connector has at least one shear connector correspondingly disposable in the block groove and the shaft groove whereby the ram shaft is releasably securable to the ram block.

The ram connector may be a rod receivable in the block groove and the shaft groove. Optionally, the ram connector may have an elliptical cross-section and/or a rectangular cross-section. The ram connector may have a handle so that an operator, a remotely operated vehicle and/or a replacement system may grip and remove the ram connector from the ram block and/or the ram shaft. The ram connector may also have a lock which may couple the ram connector to the ram block and/or the ram shaft. Optionally, the ram connector extends through the ram block, the ram head, and/or a space between the ram head and the ram block. To receive the ram connector, the block groove and the shaft groove may define a connection angle. Optionally, the shaft groove may be on a horizontal or vertical surface of the ram head. The ram block may have a receptacle for receiving the ram head of the ram shaft. The ram assembly may have a seal disposable about the ram block for sealing engagement with the tubular. The ram assembly may have a blade disposable about the ram block for severing engagement with the tubular. In another aspect, the disclosure relates to a blowout preventer for receiving a tubular of a wellbore. The blowout preventer has a body and at least one ram assembly. The body has a hole therethrough for receiving the tubular and at least one channel therethrough. Each ram assembly is positionable in a corresponding channel. The ram assembly may have a ram block for engagement with the tubular, a ram shaft for selectively extending and retracting the ram block, a ram connector for operatively connecting the ram shaft to the ram block and at least one actuator for selectively activating the ram assembly. The ram block has at least one block groove. The ram shaft has a ram head with at least one shaft groove. The ram connector includes at least one shear connector correspondingly disposable in the block groove and the shaft groove whereby the ram shaft is releasably securable to the ram block. The blowout preventer may further have a controller and/or a remote operated vehicle.

Finally, in yet another aspect, the disclosure relates to a method of assembling a ram assembly for a blowout preventer for receiving a tubular of a wellbore. The method involves providing a ram assembly having a ram block for engagement with the tubular, a ram shaft for selectively extending and retracting the ram block, a ram connector for operatively connecting the ram shaft to the ram block and a ram connector for operatively connecting the ram shaft to the ram block. The ram block has at least one block groove and a ram head with at least one shaft groove. The ram connector includes at least one shear connector. The method also involves releasably securing the ram shaft to the ram block by correspondingly disposing the shear connector in the block groove and the shaft groove.

The method may also involve disposing the ram head of the ram shaft in a receptacle of the ram block. The step of releasably securing may involve disposing the ram connector in a space between the ram shaft and the ram block, or through one of the ram shaft, the ram block or combinations thereof.

DETAILED DESCRIPTION

The description that follows includes exemplary apparatuses, systems, methods, techniques, and instruction sequences that embody techniques of the present subject matter. However, it is understood that the described embodiments may be practiced without these specific details.

The techniques herein relate to devices, such as ram connectors, used with ram blocks of a blowout preventer. These techniques may be used to provide more efficient removal/installation of ram blocks, and/or to provide a robust connection of the ram blocks to the blowout preventer. These techniques may involve one or more of the following, among others: a robust connection between the ram shaft and the ram block, adaptability to wellsite equipment (e.g., various pipe diameters), enhanced interchangeability, performance under deflection and/or wellsite equipment failures, distribution and/or absorption of loads, reduced space requirements, enhanced manufacturing capabilities (e.g., wider tolerances), balanced pressures, and increased capacity (e.g., load, pressure, etc.)

FIG. 1depicts an offshore wellsite100having a ram block assembly102in a blowout preventer (BOP)104. The ram block assembly102may be configured to seal a wellbore106, and/or sever a pipe108in the wellbore106. The BOP104may be part of a subsea system110positioned on a floor112of the sea. The subsea system110may also comprise the pipe (or tubular)108extending from the wellbore106, a wellhead114about the wellbore106, a conduit116extending from the wellbore106and other subsea devices, such as a stripper and a conveyance delivery system (not shown).

The ram block assembly102may have a ram block118, a ram shaft120and a ram connector122(shown schematically). The ram connector122may be configured to allow for the quick removal and installation of the ram block118from the ram shaft120, as will be discussed in more detail below. A remotely operated vehicle (ROV)136may be deployed from the surface to access the ram block assembly102in the BOP104to complete the removal and/or installation process.

While the offshore wellsite100is depicted as a subsea operation, it will be appreciated that the wellsite100may be land or water based, and the ram block assembly102may be used in any wellsite environment. The pipe108may be any suitable tubular and/or conveyance for running tools into the wellbore106such as a drill string, a casing, a production tubing, a tool joint, a bottom hole assembly, a wireline, a coiled tubing, and the like.

A surface system124may be used to facilitate operations at the offshore wellsite100. The surface system124may include a rig126, a platform128(or vessel) and a surface controller130. Further, there may be one or more subsea controllers132. While the surface controller130is shown as part of the surface system124at a surface location, and the subsea controller132is shown as part of the subsea system110in a subsea location, it will be appreciated that one or more controllers130,132may be located at various locations to control the surface and/or subsea systems.

To operate the ram block assembly102and/or other devices associated with the wellsite100, the surface controller130and/or the subsea controller132may be placed in communication therewith. The surface controller130, the subsea controller132, and/or any devices at the wellsite100may communicate via one or more communication links134. The communication links134may be any suitable communication system and/or device, such as hydraulic lines, pneumatic lines, wiring, fiber optics, telemetry, acoustics, wireless communication, any combination thereof, and the like. The ram block assembly102, the BOP104, and/or other devices at the wellsite100may be automatically, manually, and/or selectively operated via the controllers130and/or132.

FIGS. 2 and 3show schematic views of BOPs104a,104busable as the BOP104ofFIG. 1. While the BOPs104a,104bare depicted as having specific configurations, it will be appreciated that the BOP used with the ram assembly102and ram connector122provided herein may be any conventional BOP that provides access thereto. Examples of BOPs that may be used are described in U.S. Pat. Nos. 5,735,502, 5,897,094 and 7,044,430. The selected BOP may have a variety of shapes, and be provided with other devices, such as sensors (not shown).

The BOP104aofFIG. 2has a hole200through a central axis202of the BOP104a. The hole200may be for receiving the pipe108. The BOP104ahas multiple ram block assemblies102. The BOP104amay have one or more channels204for receiving the ram block assemblies102. As shown, there are two channels204, each with a ram block assembly102therein. The channels204may be configured to guide the ram blocks118radially toward and away from the pipe108. The BOP104amay allow the pipe108to pass through the BOP104aduring normal operation, such as run in, drilling, logging, and the like. In the event of an upset, or a pressure surge, the BOP104amay sever the pipe108and/or seal the hole200in order to prevent fluids from being released from the wellbore106.

The BOP104a, as shown, has one ram block assembly102with blades206for severing the pipe108, and one ram block assembly102with a seal208for sealing the hole200and/or the annulus around the pipe108. Each of the ram block assemblies102may have the ram blocks118, the ram shaft120and the ram connector122. The ram shaft120may couple to an actuator210(shown schematically). The actuator210may be configured to move the ram shaft120and the ram blocks118between an operating position, as shown inFIG. 2, and an actuated position wherein the ram blocks118have severed the pipe108and/or sealed the hole200. The actuator210may be any suitable actuator such as a hydraulic actuator, a pneumatic actuator, a servo, and the like.

The ram block assembly102ofFIG. 3includes the ram block118, the ram shaft120, and the ram connector122as previously described. The ram block118shown inFIG. 3, is configured to support a seal338. The BOP104bmay have a bonnet320(or door) for accessing the ram block assembly102. The bonnet320, as shown, has a hinge322, a ram cylinder324, an alignment channel326, and a connection system328. The hinge322may be for pivotally mounting the bonnet320to the BOP104b. The ram cylinder324may provide stroke, or length, for the ram shaft120between the ram block118and an actuator310(or cylinder). The alignment channel326may be configured to align with one or more channels325of the BOP104bwhen the bonnet320is closed. The alignment channel326may be configured to house the ram block assembly102, or a portion thereof, when the ram block assembly102is in the operating position.

The connection system328, as shown, may be any suitable device, or system for sealing and coupling the bonnet320to the BOP104b, and thereby aligning the ram block118with the alignment channel326. Although, the bonnet320, is shown, as a hinged bonnet, it should be appreciated that any suitable bonnet or door may be used to allow access to the ram blocks118, and/or the ram connector122. When the bonnet320is open, the ram connector122may be accessed in order to remove and/or replace the ram block118.

The ram block118may be configured to couple to the ram shaft120with the ram connector122. The ram block118may be any suitable ram block for supporting the blade206and/or the seal338, so long as the ram block118is configured to receive the ram connector122. The ram shaft120may be configured to couple to the actuator310in order to move the ram block118. The ram shaft120may be any suitable ram shaft for moving the ram block118.

The ram connector122may be a removable shear connection configured to couple the ram shaft120to the ram block118(as will be discussed in more detail below). To uncouple the ram block118from the ram shaft120, an operator, ROV136(FIG. 1), and/or a replacement system may grip the ram connector122and remove it from the ram block118and/or the ram shaft120. When the ram connector122is removed, the shear connection between the ram block118and the ram shaft120is lost and the ram block118may be disconnected (or separated) from the ram shaft120.

The ram connector122may allow for a robust connection between the ram block118and the ram shaft120. The connection may not require the ram block118to be moved perpendicular to the ram shaft120in order to disconnect. This may allow a portion of the ram block118to be located within the bonnet320while the ram connector122is removed. This may allow the ram shaft120to be shorter than traditional ram shafts, thereby saving space and money. The ram connector122may have a number of configurations so long as the ram connector122is configured to be a removable shear connection between the ram block118and the ram shaft120.

FIGS. 4A-4Cdepict various exploded views of the ram block assembly102. The ram block assembly102has the ram block118, the blade206, the ram shaft120and the ram connector122. The ram shaft120may have an actuator portion440, a shaft portion442and a shaft connector444. The actuator portion440of the ram shaft120may be configured to couple to the actuator210(as shown inFIG. 2). The shaft portion442may be any device suitable for moving the ram blocks118between the operating position and the engaged position. As shown, the shaft442is a cylinder.

The shaft connector444may be any suitable device capable of forming a shear connection with the ram connector122. As shown, the shaft connector444may be a shaped head446having one or more shaft grooves448for receiving a portion of the ram connector122. As shown, the one or more shaft grooves448are two semi-circular grooves on a top450and a bottom452of the shaped head446. The ram connector122may be configured to rest partially within the semi-circular grooves in a connected position, thereby preventing the ram shaft120from uncoupling from the ram block118. Having one or more shaft grooves448extend along a length of the shaped head446may further prevent pivoting between the ram shaft120and the ram blocks118during operation. Although the shaft connector444is shown as having the two semi-circular grooves on the top450and the bottom452of the shaped head446, any suitable design for creating a shear connection between the ram connector122and the ram shaft120may be used. For example, the one or more shaft grooves448may extend from the top450to the bottom452of the shaped head446, the one or more shaft grooves448may be holes, apertures, square, hexagonal, polygonal, triangular, and the like.

The ram blocks118may have a tool receiving end454and a ram connector end456. The tool receiving end454may be for receiving the blade206, and/or the seal208(as shown inFIG. 2). The ram connector end456may be any suitable device for forming a shear connection with the ram connector122, and thereby the ram shaft120. As shown inFIG. 4A, the ram connector end456may have one or more apertures458and a ram shaft receiving portion460(or receptacle) as shown inFIG. 4B. The one or more apertures458may be located on the outer surface of the ram block118. The one or more apertures458may be configured to receive the ram connector122into the ram block118. The apertures458may allow the ram connector122to pass through the outer surface of the ram block118, and into the ram shaft receiving portion460. One or more additional holes459may be provided for connecting portions of the ram block118.

The ram shaft receiving portion460, as shown inFIG. 4B, may be specifically shaped to receive the shaped head446of the shaft connector444. The ram receiving portion460may further have one or more block grooves462. The one or more block grooves462may be configured to substantially mirror the one or more shaft grooves448on the shaped head446. As shown inFIG. 4B, the one or more block grooves462may be any suitable shape, or may not be present at all. If the one or more block grooves462are not present, the one or more apertures458may extend partially, or wholly, through the other side of the ram block118in order to provide stability.

The ram connector122may be any suitable, removable device for forming a shear connection between the ram block118and the ram shaft120. The ram connector122as shown, has one or more shear connectors464and a handle466. The shear connector(s)464, as shown, are two cylinders configured to pass through the apertures458and into a space formed by the one or more shaft grooves448and the one or more block grooves462. Although the shear connectors464are shown as two cylinders, the shear connectors464may be any suitable shaped device for being received by the ram blocks118and the ram shaft120. Further, there may be any suitable number of shear connectors464.

The handle466, as shown inFIGS. 4A-4C, may be an extension that the operator, the ROV136(FIG. 1) and/or a replacement system may grip. The handle466may be any suitable shape that allows for the gripping and removal of the ram connector122from the ram block118and/or the ram shaft120.

The ram connector122may lock to the ram block118and/or the ram shaft120using any suitable method. For example, a lock467, such as a bolt, may couple to the ram block118through a handle aperture468, as shown inFIG. 4B.

FIGS. 5A and 5Bdepict schematic, vertical cross-sectional views of a portion of a ram block assembly102a,busable as the ram block assembly102ofFIG. 1. In each of these figures, the ram block assembly102a,bhas the ram blocks118with the ram shaft120and the ram connector122in a connected position. In the position shown, any movement (or force) experienced by the ram shaft120and/or the ram blocks118may be transferred through the ram connector122. Although, the ram connector122is shown as coupling the ram block118to the ram shaft120along a wide axis of the ram block118, it should be appreciated that the ram connector122may extend from the top to the bottom of the ram block118(as shown schematically inFIG. 2).

The ram block assemblies102a,bmay be the same as the ram block assembly102previously described herein. The ram block assemblies102a,bof FIGS.5A,5B have a shear connector464a,b, one or more shaft grooves448a,band one or more block grooves462a,bhaving elliptical and square cross-sections, respectively. Each of the shear connectors464a,bof the ram connector122is located in corresponding space(s)570a,bcreated by the one or more shaft grooves448a,bof the ram shaft120, and the one or more block grooves462a,bof the ram block118. The ram connector122forms the shear connection with an elliptical and square cross section, and the space(s)570a,bformed by the one or more shaft grooves448a,band the one or more block grooves462a,bare elliptical and square, respectively.

FIGS. 6A-6Care schematic, horizontal cross-sectional views of a portion of ram block assemblies102d-fusable as the ram block assembly102. Each of the ram block assemblies102d-fhave various ram connectors122d-fusable as the ram connector122for forming a shear connection between the ram shaft120and the ram block118.

In the version ofFIG. 6A, the ram connector122dis positionable vertically through the ram block assembly102d. The ram connector122dmay extend from the top of the ram block118toward the bottom of the ram block118in corresponding space(s)670dcreated between one or more shaft grooves448dof the ram shaft120dand one or more block grooves462dof the ram block118. The shaft grooves448dare positioned along opposite lateral sides of the shaped head446of the ram shaft120. The corresponding block grooves462dare positioned along the ram block118adjacent to the shaft grooves448d. The grooves462d,448dare positioned to receive the ram connector122dtherethrough.

In the version ofFIG. 6B, the ram connector122emay extend from the ram shaft120into the ram block118in a radial manner. Shaft grooves448eare positioned in the shaped head446of the ram shaft120and corresponding block grooves462eare positioned in the ram block118for receiving the ram connector122e. With the ram connector122eextending radially through the ram shaft120, corresponding space(s)670e, and into the ram block118, a shear connection is formed by the angle of the ram connector122e. Although, the ram connector122eis shown extending radially away from the ram shaft120, it may be formed in any suitable direction.

In the version ofFIG. 6C, the ram connector122fmay extend through the ram block118, corresponding space(s)670f, and the ram shaft120. Shaft grooves448fare positioned in the shaped head446of the ram shaft120and corresponding block grooves462fare positioned in the ram block118for receiving the ram connector122f. With the ram connector122fextending through the ram block118and the ram shaft120, a shear connection is formed therethrough. Although, the ram connector122fis shown extending horizontally through the ram block118and ram shaft120, it may be formed in any suitable direction.

FIG. 7is a flow chart depicting a method700of assembling a ram block assembly for a blowout preventer. The method involves providing (770) a ram assembly including a ram block for engagement with the tubular (the ram block having at least one block groove), a ram shaft for selectively extending and retracting the ram block (the ram shaft having a ram head with at least one shaft groove), and a ram connector for operatively connecting the ram shaft to the ram block (the ram connector including at least one shear connector). The method further involving releasably securing (772) the ram shaft to the ram block by correspondingly disposing the shear connector in the block groove and the shaft groove.

The steps of the method may be performed in any order, and repeated as desired.

It will be appreciated by those skilled in the art that the techniques disclosed herein can be implemented for automated/autonomous applications via software configured with algorithms to perform the desired functions. These aspects can be implemented by programming one or more suitable general-purpose computers having appropriate hardware. The programming may be accomplished through the use of one or more program storage devices readable by the processor(s) and encoding one or more programs of instructions executable by the computer for performing the operations described herein. The program storage device may take the form of, e.g., one or more floppy disks; a CD ROM or other optical disk; a read-only memory chip (ROM); and other forms of the kind well known in the art or subsequently developed. The program of instructions may be “object code,” i.e., in binary form that is executable more-or-less directly by the computer; in “source code” that requires compilation or interpretation before execution; or in some intermediate form such as partially compiled code. The precise forms of the program storage device and of the encoding of instructions are immaterial here. Aspects of the invention may also be configured to perform the described functions (via appropriate hardware/software) solely on site and/or remotely controlled via an extended communication (e.g., wireless, internet, satellite, etc.) network.

While the embodiments are described with reference to various implementations and exploitations, it will be understood that these embodiments are illustrative and that the scope of the inventive subject matter is not limited to them. Many variations, modifications, additions, and improvements are possible. For example, one or more BOPs with various combinations of one or more shear connections between the ram block and the ram shaft may be used.