FIELD OF THE DISCLOSURE

This disclosure is directed generally to pressure control equipment at the wellhead, and more specifically to a remotely-operated wellhead pressure control apparatus. Broadly, and without limiting the scope of this disclosure, one embodiment of the disclosed pressure control apparatus is a cam-locking wellhead attachment that can secure a connection to a pressurized wellhead connection remotely, without manual interaction at the wellhead. Additional embodiments of other innovative high pressure seals for wellhead pressure control fittings are also disclosed.

BACKGROUND OF THE DISCLOSED TECHNOLOGY

Conventionally, wellhead connections to pressure control equipment are typically made by either a hand union or hammer union. Wellhead operators engaging or disengaging these conventional types of wellhead connections place themselves in danger of injury. The pressure control equipment to be connected to the wellhead is typically heavy, and remains suspended above the wellhead operator via use of a crane. Interacting with the crane operator, a technician at the wellhead below must struggle with the suspended load as it is lowered in order to achieve the proper entry angle into the wellhead to make a secure connection. The wellhead operator must then connect the wellhead to the pressure control equipment to the wellhead, typically via a bolted flanged connection. The bolts must be tightened manually by a person at the wellhead, typically via a “knock wrench” struck with a sledgehammer in order to get the bolts sufficiently tight to withstand the internal operating pressure. During this whole process, as noted, the operator is in physical danger of injuries, such as collision with the suspended pressure control equipment load, or pinched or crushed fingers and hands when securing the connection.

Wellhead operators are exposed to similar risks of injury during conventional removal of the pressure control equipment from the wellhead. The removal process is substantially the reverse of the engagement process described in the previous paragraph.

There is therefore a need in the well services industry to have a way to safely connect and disconnect pressure control equipment from the wellhead while minimizing the physical danger to human resources in the vicinity. The disclosed embodiments of high pressure seals for wellhead pressure control fittings are all hydraulically-actuated and -deactuated systems that lock pressure control equipment to the wellhead via a remote control station.

SUMMARY AND TECHNICAL ADVANTAGES

These and other drawbacks in the prior art are addressed by the disclosed embodiments of high pressure seals for wellhead pressure control fittings. Disclosed embodiments include a cam lock design with a secondary lock, in which the cam lock pressure control apparatus replaces connections done conventionally either by hammering, torquing, or with a quick union nut, all of which require the interaction of an operator to perform these operations. This disclosure describes exemplary cam lock embodiments in both larger and smaller diameter configurations to suit corresponding size ranges of wellheads. In such embodiments, a crane operator may place pressure control equipment (PCE) directly onto the wellhead via the apparatus's highly visible entry guide (“tulip”). The crane operator may then proceed to actuate the cam lock control apparatus and secure the pressure control equipment in embodiments where the crane is equipped with the apparatus's remote controls. In alternative embodiments, a second operator may operate the cam lock control apparatus remotely while the crane holds the pressure control equipment in the tulip. In currently preferred embodiments, the disclosed cam lock pressure control apparatus allows the pressure control equipment to be secured in the wellhead from up to 100 feet away from the wellhead, although the scope of this disclosure is not limited in this regard.

As noted, disclosed embodiments of the disclosed cam lock pressure control apparatus provide a secondary mechanical lock feature that holds the locked pressure connection secure without total loss in hydraulic pressure. Preferably, the apparatus may be adapted to fit any conventional wellhead, and may be available in several sizes, such as (without limitation) for 3-inch to 7-inch pipe. As noted, this disclosure describes exemplary cam lock embodiments in both larger and smaller diameter configurations to suit corresponding size ranges of wellheads. Although not limited to any particular pressure rating, the disclosed cam lock pressure control apparatus is preferably rated up to about 15,000 psi MAWP (maximum allowable working pressure). Although the embodiments described in this disclosure are described for applications in the oilfield industry, the disclosed cam lock pressure control apparatus is not limited to such applications. It will be appreciated that the apparatus also has applications wherever highly pressurized joint connections can be made more safely by remote actuation and deactuation.

Embodiments of the disclosed pressure control apparatus preferably also provide a “nightcap” option to cap the well if there will be multiple operations. Consistent with conventional practice in the field, the apparatus includes a nightcap option, available separately, for sealing off the wellhead while the PCE has been temporarily removed, such as at the end of the day. Embodiments including the nightcap enable the apparatus to remain connected to the wellhead, and wellhead pressure to be retained, in periods when PCE is temporarily removed. In such embodiments, the disclosed pressure control apparatus does not have to be removed and re-installed on the well head every time PCE is removed. Such embodiments obviate the need to suspend wellhead operations unnecessarily just to remove and re-install the apparatus every time PCE is removed.

It is therefore a technical advantage of the disclosed pressure control apparatus to reduce substantially the possibility of personal injury to wellhead operators during engagement and disengagement of pressure control equipment from wellheads. In addition to the paramount importance of providing a safe workplace, there are further ancillary advantages provided by the disclosed pressure control apparatus, such as improved personnel morale and economic advantages through reduction of lost time accidents and increased efficiency gains of more rapid rig ups.

Another technical advantage of the disclosed pressure control apparatus is that it provides a hands-free, secure, predictable connection between pressure control equipment and the wellhead. The disclosed primary cam-lock, in combination with the secondary lock feature, provides a predictable serviceably-tight connection every time. This is distinction to possible variances in the tightness provided by conventional hand- and knock wrench-tightening of the connection, whose degree of tightness may vary according to the technique and physical strength of the manual operator.

A further technical advantage of the disclosed pressure control apparatus is that, in embodiments in which a quick test port is provided, a conventional hand pump can conveniently deliver high pressure fluid to a portion of the pressure connection sealed between two sets of o-rings. It will be appreciated that the o-rings will limit or impede high pressure fluid flow into or out of the portion of the pressure connection between the two sets of o-rings. Embodiments of this disclosure provide a quick test port though the pressure control assembly into the flow-limited portion of the pressure connection. A hand pump may then be used to deliver fluid through the quick test port to the flow-limited portion. This allows the pressure integrity of the seals provided by the o-rings to be tested prior to applying high fluid pressures from the wellhead onto the pressure control apparatus's pressure connection. In other applications, the quick test port may be used to equalize pressure in the flow-limited portion of the pressure connection during service engagement and disengagement of the pressure control apparatus from the wellhead.

Disclosed additional embodiments of high pressure seals for wellhead pressure control fittings describe a wedge seal design and a spring-driven ball race seal design that substitute for the cam lock design. The wedge seal design and spring-driven ball race seal design differentiate functionally over the cam lock design primarily in the mechanism by which a high pressure seal is provided. The cam design provides piston-actuated rotating cams whose perimeter curvatures bear down on a shaped shoulder formed in the exterior surface of a PCE adapter. The adapter is received into a receptacle assembly connected to the wellhead, so that the cams compress the adapter into the receptacle to form a high pressure seal. By contrast, the wedge seal design provides opposing sliding wedges. Opposing sloped sides on the wedges slide together in reciprocating motion responsive to hydraulic pressure, causing the PCE adapter to be compressed into the wellhead assembly to form a high pressure seal. By contrast again, the spring-driven ball race seal design compresses the PCE adapter into the wellhead assembly by forcing, again responsive to hydraulic pressure, an annular member over a cylindrical ball race and into a tight fit (1) inside an annular receptacle, and (2) between ball bearings in the ball race and receiving grooves in the adapter. Similar to the cam lock design, the wedge seal design and spring-driven ball race seal design are both also remotely actuated and deactuated via hydraulic control, and therefore provide many of the same technical advantages described above.

According to a first cam lock aspect, therefore, this disclosure describes embodiments of a wellhead pressure control fitting comprising a generally tubular Pressure Control Equipment (PCE) adapter having first and second adapter ends, the first adapter end configured to mate with pressure control equipment, the second adapter end providing a shaped end including an adapter end curvature; a generally tubular pressure control assembly having first and second assembly ends, the first assembly end providing a first assembly end interior and a first assembly end exterior, the second assembly end configured to mate with a wellhead; the first assembly end exterior having an exterior periphery, the exterior periphery providing a plurality of cam locks, each cam lock disposed to rotate about a corresponding cam lock pin, each cam lock pin anchored to the first assembly end exterior, each cam lock further providing a cam perimeter curvature; the first assembly end exterior further providing a plurality of cam lock pistons, one cam lock piston for each cam lock, wherein extension and retraction of the cam lock pistons causes rotation of the cam locks in opposing directions about their corresponding cam lock pins; the first assembly end exterior further providing a plurality of locking ring pistons, a locking ring connected to the locking ring pistons at a distal end thereof, the locking ring encircling the first assembly end proximate the cam locks, wherein extension of the locking ring pistons causes the locking ring to move to a position free of contact with the cam locks as the cam locks rotate about the cam lock pins, and wherein retraction of the locking ring pistons causes the locking ring to move so as to restrain the cam locks from rotation about the cam lock pins; the first assembly end interior providing a receptacle for receiving the second adapter end, the second adapter end and the receptacle further each providing cooperating abutment surfaces, the cooperating abutment surfaces forming a high pressure seal between the second adapter end and the receptacle when the second adapter end is compressively received into the receptacle; wherein, as the second adapter end enters the receptacle and engages the cooperating abutment surfaces, extension of the cam lock pistons causes the cam locks to rotate about the cam lock pins, which in turn causes the cam perimeter curvatures on the cam locks to cooperatively bear down on the adapter end curvature, which in turn compresses the second adapter end into the receptacle to form the high pressure seal; and wherein, once the high pressure seal is formed, retraction of the locking ring pistons causes the locking ring to move so as to restrain the cam locks from rotation about the cam lock pins.

In a second cam lock aspect, embodiments of the wellhead pressure control fitting include that each cam lock further provides a cam perimeter notch, each cam perimeter notch configured to engage the second adapter end as the second adapter end approaches entry into the receptacle.

In a third cam lock aspect, embodiments of the wellhead pressure control fitting include that the second assembly end further provides a vent line.

In a fourth cam lock aspect, embodiments of the wellhead pressure control fitting include that the second adapter end provides at least one o-ring seal configured to mate with the receptacle when the second adapter end is received into the receptacle.

In a fifth cam lock aspect, embodiments of the wellhead pressure control fitting include that the second adapter end provides at least first and second o-ring seals, and in which the first assembly end further provides a quick test port, the quick test port comprising a fluid passageway from the first assembly end exterior through to the first assembly end interior, wherein the quick test port is open to the first assembly end interior at a location selected to lie between the first and second o-ring seals when the second end adapter and the receptacle form the high pressure seal.

In a sixth cam lock aspect, embodiments of the wellhead pressure control fitting include that the locking ring is in an interference fit with the cam locks when retraction of the locking ring pistons causes the locking ring to move so as to restrain the cam locks from rotation about the cam lock pins.

In a seventh cam lock aspect, embodiments of the wellhead pressure control fitting include that each cam lock piston is connected to its corresponding cam lock via a pinned cam linkage, each pinned cam linkage including a link arm interposed between the cam lock piston and cam lock, each link arm connected to the cam lock via a first linkage pin, each link arm connected to the cam lock piston by a second linkage pin.

In an eighth cam lock aspect, embodiments of the wellhead pressure control fitting include that the cooperating abutment surfaces include a machined shoulder surface and a machined slope surface provided on the second adapter end, the receptacle further providing machined surfaces to mate with the shoulder surface and slope surface in forming the high pressure seal.

In a ninth cam lock aspect, embodiments of the wellhead pressure control fitting include that the PCE adapter is interchangeable with a generally tubular night cap adapter, the night cap adapter having first and second night cap ends, wherein the first night cap end is closed and sealed off against internal pressure, and wherein the second night cap end is dimensionally identical to the second adapter end on the PCE adapter.

According to a first aspect of the disclosed additional embodiments of high pressure seals for wellhead pressure control fittings, therefore, this disclosure describes embodiments of a wellhead pressure control fitting comprising a generally tubular Pressure Control Equipment (PCE) adapter having first and second adapter ends, the first adapter end configured to mate with pressure control equipment, the second adapter end providing an annular first adapter rib, a generally tubular pressure control assembly having first and second assembly ends and a longitudinal centerline, the centerline defining axial displacement parallel to the centerline and radial displacement perpendicular to the centerline, the first assembly end providing a first assembly end interior, the second assembly end configured to mate with a wellhead, the first assembly end interior providing a PCE receptacle for receiving the second adapter end, the second adapter end and the PCE receptacle further each providing cooperating abutment surfaces, the cooperating abutment surfaces forming a pressure seal between the second adapter end and the PCE receptacle when the second adapter end is compressively received into the PCE receptacle, the first assembly end interior further providing a lower wedge assembly, the lower wedge assembly including a plurality of lower wedges, each lower wedge having first and second opposing lower wedge sides, each first lower wedge side providing protruding top and bottom lower wedge ribs, a generally hollow lower wedge receptacle, the lower wedge receptacle further providing a plurality of shaped lower wedge receptacle recesses formed in an interior thereof, one lower wedge receptacle recess for each lower wedge, the lower wedge receptacle further having first and second opposing lower wedge receptacle sides in which the lower wedge receptacle recesses define the first lower wedge receptacle side, and wherein each lower wedge is received into a corresponding lower wedge receptacle recess so that the first lower wedge receptacle side and the second lower wedge sides provide opposing sloped lower wedge surfaces, wherein axial displacement of the lower wedge receptacle relative to the lower wedges causes corresponding radial displacement of the lower wedges, and wherein, as the second adapter end enters the PCE receptacle and engages the cooperating abutment surfaces, axial displacement of the lower wedge receptacle relative to the lower wedges causes corresponding radial constriction of the top and bottom lower wedge ribs around the first adapter rib and the PCE receptacle, which in turn compresses the second adapter end into the PCE receptacle to form the pressure seal.

In a second aspect of additional seals, embodiments of the wellhead pressure control fitting include that axial displacement of the lower wedge receptacle relative to the lower wedges is enabled by hydraulically-actuated forces exerted against the second lower wedge receptacle side by a hydraulic mechanism selected from the group consisting of (a) a plurality of cooperating hydraulically-pressurized lower chambers acting on the lower wedge receptacle, and (b) at least one extensible and retractable hydraulic lower piston acting on the lower wedge receptacle.

In a third aspect of additional seals, embodiments of the wellhead pressure control fitting include that the adapter provides an annular second adapter rib distal from the first adapter rib towards the first adapter end, and in which the first assembly end interior further provides an upper wedge assembly, the upper wedge assembly including a plurality of upper wedges, each upper wedge having first and second opposing upper wedge sides, each first upper wedge side providing protruding top and bottom upper wedge ribs, a generally hollow upper wedge receptacle, the upper wedge receptacle further providing a plurality of shaped upper wedge receptacle recesses formed in an interior thereof, one upper wedge receptacle recess for each upper wedge, the upper wedge receptacle further having first and second opposing upper wedge receptacle sides in which the upper wedge receptacle recesses define the first upper wedge receptacle side, and wherein each upper wedge is received into a corresponding upper wedge receptacle recess so that the first upper wedge receptacle side and the second upper wedge sides provide opposing sloped upper wedge surfaces, wherein axial displacement of the upper wedge receptacle relative to the upper wedges causes corresponding radial displacement of the upper wedges, and wherein, as the second adapter end enters the PCE receptacle and engages the cooperating abutment surfaces, axial displacement of the upper wedge receptacle relative to the upper wedges causes corresponding radial constriction of the top and bottom upper wedge ribs around the second adapter rib, which in turn restrains the adapter from axial displacement relative to the PCE receptacle.

In a fourth aspect of additional seals, embodiments of the wellhead pressure control fitting include that axial displacement of the upper wedge receptacle relative to the upper wedges is enabled by hydraulically-actuated forces exerted against the second upper wedge receptacle side by a hydraulic mechanism selected from the group consisting of (a) a plurality of cooperating hydraulically-pressurized upper chambers acting on the upper wedge receptacle, and (b) at least one extensible and retractable hydraulic upper piston acting on the upper wedge receptacle.

In a fifth aspect of additional seals, embodiments of the wellhead pressure control fitting include that he upper and lower wedge assemblies operate independently.

In a sixth aspect of additional seals, embodiments of the wellhead pressure control fitting include that the cooperating abutment surfaces include a machined shoulder surface and a machined slope surface provided on the second adapter end, the PCE receptacle further providing machined surfaces to mate with the shoulder surface and slope surface in forming the pressure seal.

In a seventh aspect of additional seals, embodiments of the wellhead pressure control fitting comprise a generally tubular Pressure Control Equipment (PCE) adapter having first and second adapter ends, the first adapter end configured to mate with pressure control equipment, the adapter providing an annular adapter rib distal from the first adapter end towards the second adapter end, a generally tubular pressure control assembly having first and second assembly ends and a longitudinal centerline, the centerline defining axial displacement parallel to the centerline and radial displacement perpendicular to the centerline, the first assembly end providing a first assembly end interior, the second assembly end configured to mate with a wellhead, the first assembly end interior providing a PCE receptacle for receiving the second adapter end, the second adapter end and the PCE receptacle further each providing cooperating abutment surfaces, the cooperating abutment surfaces forming a pressure seal between the second adapter end and the PCE receptacle when the second adapter end is received into the PCE receptacle, the first assembly end interior further providing a wedge assembly, the wedge assembly including a plurality of wedges, each wedge having first and second opposing wedge sides, each first wedge side providing protruding top and bottom wedge ribs, a generally hollow wedge receptacle, the wedge receptacle further providing a plurality of shaped wedge receptacle recesses formed in an interior thereof, one wedge receptacle recess for each wedge, the wedge receptacle further having first and second opposing wedge receptacle sides in which the wedge receptacle recesses define the first wedge receptacle side, and wherein each wedge is received into a corresponding wedge receptacle recess so that the first wedge receptacle side and the second wedge sides provide opposing sloped wedge surfaces, wherein axial displacement of the upper receptacle relative to the wedges causes corresponding radial displacement of the wedges, and wherein, as the second adapter end enters the PCE receptacle and engages the cooperating abutment surfaces, axial displacement of the wedge receptacle relative to the wedges causes corresponding radial constriction of the top and bottom wedge ribs around the adapter rib, which in turn restrains the adapter from axial displacement relative to the PCE receptacle.

In an eighth aspect of additional seals, embodiments of the wellhead pressure control fitting include that axial displacement of the wedge receptacle relative to the wedges is enabled by hydraulically-actuated forces exerted against the second wedge receptacle side by a hydraulic mechanism selected from the group consisting of (a) a plurality of cooperating hydraulically-pressurized chambers acting on the wedge receptacle, and (b) at least one extensible and retractable hydraulic piston acting on the wedge receptacle.

In a ninth aspect of additional seals, embodiments of the wellhead pressure control fitting comprise a generally tubular Pressure Control Equipment (PCE) adapter having first and second adapter ends, the first adapter end configured to mate with pressure control equipment, an elongate adapter sealing portion formed on the second adapter end, a generally tubular receptacle, the receptacle having first and second receptacle ends, the second receptacle end configured to mate with a wellhead, an elongate receptacle sealing portion formed on the first receptacle end, wherein a pressure seal is formed between the adapter sealing portion and the receptacle sealing portion when the adapter sealing portion is fully received over the receptacle sealing portion and constrained radially outwards, a generally tubular lower body, the lower body having first and second lower body ends, the lower body received over the receptacle and rigidly affixed to the receptacle at the lower body second end, the first lower body end extending parallel with the receptacle sealing portion and positioned to constrain the adapter portion radially when the adapter sealing portion is fully received over the receptacle sealing portion, a generally cylindrical ball race, the ball race having first and second ball race ends, the ball race providing a plurality of holes in a circumferential pattern proximate the second ball race end, the ball race positioned such that the second ball race end contacts the first lower body end, a plurality of ball bearings each received from outside the ball race into a corresponding hole, the holes each having a hole diameter such that the ball bearings protrude through the holes without passing through the holes while still allowing the ball bearings to roll freely as received in the holes, at least one annular adapter groove formed on an exterior of the adapter, the adapter groove positioned and shaped to receive the ball bearings through the ball race holes when the adapter sealing portion is fully received over the receptacle sealing portion, wherein the adapter sealing portion and the receptor sealing portion are locked in sealing engagement when the ball bearings are compressed radially into the adapter groove, a generally tubular floating member, the floating member having first and second floating member ends, the floating member received over the ball race and the lower body, wherein an interior of the first floating member end is in rolling engagement with the ball bearings while retaining the ball bearings in their holes, and wherein an interior of the second floating member end is in sliding sealing engagement with an exterior of the first lower body end, a generally tubular sleeve, the sleeve having first and second sleeve ends, the sleeve received over the ball race, the floating member and the lower body wherein the an exterior of the second floating member end is in sliding sealing engagement with an interior of the sleeve, the second sleeve end rigidly and sealingly affixed to the lower body at the lower body second end so as to create a lower chamber below the second floating member end, the first sleeve end rigidly and sealingly affixed to the ball race so as to create an upper chamber above the first floating member end, wherein hydraulic pressure introduced into the upper chamber encourages the floating member to slide towards the second sleeve end, which in turn causes a thicker portion of the floating member to compress the ball bearings radially, and wherein hydraulic pressure introduced the lower chamber encourages the floating member to slide towards the first sleeve end, which in turn causes a thinner portion of the floating member to release the ball bearings from radial compression.

In a tenth aspect of additional seals, embodiments of the wellhead pressure control fitting further at least one o-ring on an exterior of the receptacle sealing portion.

The foregoing has outlined rather broadly some of the features and technical advantages of the technology embodied on the disclosed high pressure seals for wellhead pressure control fittings, in order that the detailed description that follows may be better understood. Additional features and advantages of the disclosed technology may be described. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same inventive purposes of the disclosed technology, and that these equivalent constructions do not depart from the spirit and scope of the technology as described and as set forth in the appended claims.

