Remote-controlled Oil Well Pipe Shear And Shutoff Apparatus

Abstract

In an offshore oil well production system including a surface platform, a submerged wellhead, and a pipe string interconnecting the wellhead and platform, the provision of a pipe shear and shutoff apparatus between the platform and wellhead having a housing with a throughbore with an enlarged intermediate chamber and end bores for receiving a section of the pipe and means within the apparatus for shearing the pipe and closing the fluid passage through the apparatus when the pipe is severed, means for selective actuation of the apparatus and remote control means for the actuating means which is operative at a remote location from the wellhead notwithstanding the loss of physical connection between the platform and wellhead through the pipe string, such as when the pipe string is ruptured.

Description

The present invention relates to an apparatus for use in connection with oil well offshore production systems wherein a surface platform is stationed with respect to a wellhead and is interconnected with the wellhead through at least one pipe string. Generally, the platform or floating vessel is maintained in its relative position to the wellhead by suitably securing the floating vessel to the floor of the ocean or sea through mooring lines.

In the above-described system, as well as in various other types of offshore oil well production systems, there may be provided an apparatus for shearing the pipe string and shutting off the fluid passage in the event of rupture of the pipe string so as to prevent blowout of the well. In operation, it is necessary to actuate such apparatus so as to perform the shearing and shutoff functions. Such operation may be manual, such as by sending down a diver, but the disadvantages of such operation are apparent. In the prior art, the operation of shear and shutoff apparatus has been controlled from the surface platform. However, the defect in such prior-art systems is that if the surface platform moves relative to the wellhead so as to rupture the pipe string, it will also likely rupture any other physical means interconnecting the platform and the apparatus to be controlled. For example, if the anchor lines of the surface platform are severed by another vessel, or break because of heavy seas, there is no longer any physical connection between the surface platform and the apparatus.

In the pipe shear and shutoff apparatus known to the prior art, there is also the difficulty of reliably assuring that the fluid flow passage will be completely shut off because of the possibility that the pipe will not be properly severed. In other words, in some prior-art apparatus, the shearing means may result in crushing or deforming of the pipe which would interfere with the effective shutoff of the flow passage.

Accordingly, it is a general object of the present invention to provide a remote-controlled oil well pipe shear and shutoff apparatus that avoids all of the foregoing disadvantages of similar types of apparatus and offshore oil well production systems used heretofore.

It is another object of the present invention to provide an offshore oil well production system including a surface platform, a submerged wellhead, an interconnecting pipe string, a submerged pipe shear and shutoff apparatus, with means for remotely controlling the actuation of the apparatus so that the fluid flow passage may be shut off in the event of pipe string rupture and movement of the platform relative to the wellhead.

It is still another object of the present invention to provide an offshore oil well production system of the above-described type, wherein the remote control means may include signal transmitting and receiving apparatus carried by the platform and the pipe shear and shutoff apparatus for selective operation by an operator aboard the platform.

It is yet another object of the present invention to provide an offshore oil well production system of the above-described type wherein the remote control means may include fixed length means physically interconnecting the platform and wellhead when the platform is in a preselected location relative to the wellhead which is ruptured when the platform is moved from such preselected location so as to automatically actuate the pipe shear and shutoff apparatus.

One more object of the present invention is to provide a submerged pipe shear and shutoff apparatus wherein a pipe string may be simultaneously sheared and shut off and wherein the shutoff means is maintained in sealing relation to prevent fluid passage flow.

It is yet one more object of the present invention to provide an apparatus of the last-described type wherein the seal is maintained without physical contact between a surface platform and the wellhead which was interconnected by the pipe string prior to rupture.

Other objects and advantages of this invention will be readily apparent from the following description when considered in connection with the appended drawings.

IN THE DRAWINGS

FIG. 1 is a schematic view of an exemplary offshore oil well production system including the present invention;

FIG. 2 is a detailed view of the apparatus shown in FIG. 1 illustrating components of the system schematically;

FIG. 3 is a detailed view as in FIG. 2 showing alternate components for use in the system;

FIG. 4 is a side sectional view of the apparatus shown in FIGS. 2 and 3;

FIG. 5 is a side sectional view as in FIG. 4 showing apparatus in shutoff position;

FIG. 6 is a sectional view taken along the plane VI-VI of FIG. 4;

FIG. 7 is a sectional view taken along the plane VII-VII of FIG. 4;

FIG. 8 is a sectional view taken along the plane VIII-VIII of FIG. 4; and

FIG. 9 is a sectional view taken along the plane IX-IX of FIG. 5.

Referring now to FIGS. 1 through 3, there is shown in FIG. 1 an offshore oil well production system generally comprising a surface platform or vessel 20, a wellhead indicated generally at 21, and a production line or pipe string generally indicated at 22. The platform 20 may be fixed or supported by the floor of the body of water, or may be a floating vessel such as that illustrated at 20. The wellhead 21 is submerged or undersea and is mounted to the floor of the sea in a manner well known in the art. While a plurality of production lines or pipe strings may interconnect the wellhead and surface platform, there is shown for purposes of illustration a single pipe string 22 comprising a plurality of pipe sections which may extend generally vertically from the wellhead to the platform.

The platform 20 may be secured in its relation or position to the wellhead by means of anchor lines 23 which may be connected to a subsurface buoy 24 connected through a cable 25 to an anchor 26 on the ocean floor. Obviously, other means for maintaining the floating platform 20 in relation to the wellhead 21 may be provided as are well known in the art.

In the present invention, the offshore oil well production system is also provided with a submerged pipe shear and shutoff apparatus generally indicated at 30, means for selective actuation of the apparatus indicated generally at 80, and remote control means generally indicated at 110. The pipe shear and shutoff apparatus is submerged and may be mounted adjacent the wellhead between the platform and the wellhead. The means 60 for selective actuation of the apparatus may be carried by such apparatus as in the exemplary embodiment.

Remote control means, indicated generally at 110, in the exemplary embodiment illustrated in FIG. 2, may comprise a signal-transmitting means 111, such as a radio transmitter, carried by floating platform 20. The remote control means also includes signal-receiving means 112, as seen in FIG. 2, carried by means 80 for selective actuation of pipe shear and shutoff apparatus 30. There is shown a second exemplary embodiment of means for remote control of the apparatus-actuating means which comprises a fixed length physical means such as a fluid pressure line 115 in operative communication with the means 80 when the pipe string 22 is intact.

In operation, each of the above-described remote control means automatically renders the actuating means operative, or maintains operative connection between the apparatus and surface platform, upon movement of the platform from its preselected position relative to the wellhead. In the first embodiment, rupture of the pipe string 22 which could occur when platform 20 has broken away from its anchor line 23, severs all physical connection between the platform 20 and the pipe shear and shutoff apparatus 30. However, an operator aboard floating vessel 20 may manually transmit a signal from transmitting means 111 to signal-receiving means 112 so as to render actuating means 80 operative thereby shearing pipe string 22 and providing fluid flow shutoff. In the second embodiment, movement of the surface platform 20 so as to rupture pipe string 22 will simultaneously cause rupture of fixed length fluid pressure line 115 opening such line to ambient pressure which will render the actuating means operative so as to shear and shut off pipe string 22.

The submerged pipe shear and shutoff apparatus 30 of the present invention generally comprises a housing 32, carrier means indicated generally at 40, pipe-shearing means indicated generally at 50, closing means indicated generally at 60, means axially urging a shutoff plug into sealing relation indicated generally at 65, and the actuating means indicated generally at 80.

Referring now to FIGS. 4 through 9, there is shown an exemplary embodiment of a pipe shear and shutoff apparatus in accordance with the present invention wherein the housing 32 includes a through bore 33 which defines a work chamber 34 and top and bottom end bores 35, 36 respectively. Chamber 34 is intermediate the end bores 35, 36 and is enlarged and disposed laterally of the longitudinal axis of the pipe passing through housing 32 and indicated at P. Pipe P comprises a first pipe section P1 connected to the platform 20 and a second pipe section P2 connected to the wellhead 21. The intermediate enlarged chamber 34 may also include a second laterally disposed portion indicated at 34a for receiving the cutting blade and any portions of the pipe which may be crushed after the shearing operation is complete.

Carrier means 40 is slidably mounted for movement transverse to the axis of pipe P and is normally disposed in a zone to one side of the axis of pipe P. In the exemplary embodiment, such carrier means may comprise carrier member 41 having a downwardly directed opening 42 for receiving the actuating rod of the actuating means described hereinafter. Carrier member 41 has a generally cylindrical opening 43 for receiving a shutoff plug and has parallel sidewalls 44, 45 as seen best in FIG. 9. The carrier member 41 is slidably supported on longitudinally extending tracks 46, 47 disposed transversely to the axis of pipe P and within chamber 34 and preferably integral with housing 32, as seen in FIG. 9. Housing 32 also includes guideways 37, 38 integral with the vertical walls adjacent the tracks 46, 47, respectively, and extending longitudinally parallel with the tracks on opposite sides of carrier member 41 and in sliding engagement with carrier member sidewalls 44, 45 to guide transverse movement of the carrier member.

The pipe shear and shutoff apparatus 30 also includes pipe-shearing means indicated generally at 50 which comprises blade means 51 and anvil means 55. Blade means 51, in the exemplary embodiment, is carried by carrier member 41 for movement transverse to pipe P. The blade means comprises a blade or cutting edge 52 fixedly mounted on the forward end of carrier member 41 with fasteners 53. The cutting edge 52 has a width greater than the diameter of pipe P and has an upper edge in the same horizontal plane as the upper surface of the carrier member 41, as seen in FIGS. 4 and 5. In the preferred embodiment, the cutting edge 52 is straight and is angularly oriented with respect to the direction of movement.

The anvil means in the exemplary embodiment is fixedly mounted in the housing 32 and comprises an annular member 56 of hardened steel retained in the housing at the upper surface of the chamber by studs 57. Annular anvil member 56 is mounted at the periphery of through bore portion 35 and is sealed within the chamber housing by means of annular sealing ring 58. The lower plane of anvil member 56 is coplanar with the upper plane of carrier member 41 and cutting edge 52 so as to define a shear plane.

The pipe shear and shutoff apparatus 30 also includes closing means 60 for preventing fluid passage through housing 32 when pipe P has been severed. In the exemplary embodiment, such closing means comprises a shutoff plug 61 carried by carrier member 41 in opening 43 for transverse movement into an operative position (as seen in FIG. 5) axially aligned with through bore 33. Shutoff plug 61 comprises a substantially cylindrical, solid, metallic body 62 having an axis substantially parallel to the axis of pipe P. The shutoff plug 61 carries an annular sealing member 63 on the peripheral edge of the upper surface for sealing engagement with anvil member 56 when the shutoff plug is in the operative position.

Means 65 for axially urging the shutoff plug 61 is provided in apparatus 30 and in the exemplary embodiment comprises ramp or cam means 66 carried by housing 32 in the path of carrier member 41. Ramp means 66 includes a pair of ramp members 67, 68 positioned on opposite sides of through bore 35 within chamber 34 and integral with tracks 46, 47, as seen best in FIG. 9. The means for axially urging the shutoff plug into sealing relation with the anvil member 56 mounted in housing 32 also includes ramp surfaces 69, 70 on the lower side of shutoff plug body 62 defined by cutout portions thereof. The ramp surfaces 69, 70 have the same slope and are complementary with the ramp members 67, 68. Preferably, the ramp members and ramp surfaces have a slope so as to provide substantial friction through the metal-to-metal contact thereof so as to maintain the shutoff plug and anvil member in sealing relation.

The pipe shear and shutoff apparatus 30 includes actuating means 80 which in the exemplary embodiment comprises an actuator housing 81 defining a cylindrical chamber 82 open at one end and sealed by an end plate 83 through a plurality of fasteners 84. The opposite end of housing 81 is secured through studs and nuts 85 to the end of housing 32 of the apparatus. The engaging wall 86 of actuator housing 81 is provided with an opening 87 for receiving the actuator member 88 of a piston 89 slidably mounted in chamber 82. Piston 89 carries annular sealing members 90 while end wall 86 of housing 81 carries sealing members 91 for sealing engagement with actuator rod 88. The actuating means also comprises a high-pressure fluid source 92 as seen in FIGS. 2 and 3, in fluid communication with piston chamber 82 through a conduit 93, valve 94, and conduits 95, 96.

In the embodiment illustrated in FIG. 2, the valve 94 may be a simple single-gate valve controlled by signal receiving means 112 so as to allow the high-pressure gas to flow from source 92 through the valve through conduit 95 thereby moving piston 89 and carrier member 41 to the right, as viewed in FIGS. 4 and 5. Conduit 96 is provided for relief and for returning the carrier means to the inoperative position after the shear and shutoff apparatus has been used. In the embodiment illustrated in FIG. 3, the valve 94 is actuated by rupture of the fluid pressure line 115 opening such line to ambient pressure so that the high-pressure gas source may open the gate allowing the high-pressure gas to pass through conduit 95 and to move piston 89 as previously described.

In operation, when the carrier means is moved transverse to the pipe, the blade or cutting edge 52 severs the pipe P into portions P.sub.1 and P.sub.2. Simultaneously the shutoff plug 61 is moved into axial alignment with the through bore 33 and pipe sections P.sub.1 and P.sub.2 and is axially urged through ramp members 67, 68 and ramp surfaces 69, 70 into sealing relation with anvil member 56 so as to prevent fluid flow through the apparatus thereby preventing blowout of the well. The shutoff plug is maintained in the sealing relation by virtue of the low slope and high friction between the ramp members and ramp surfaces which maintains the shutoff plug and anvil member in contact. Moreover, it is an important feature of this invention that the shutoff plug is maintained in sealing relation by the differential in pressure across the shutoff plug. Specifically, if pipe section P.sub.2 is connected to the wellhead whereas pipe P.sub.1 is connected to the platform and is the pipe that will be ruptured, the pressure acting on the underside of the shutoff plug will be the well pressure whereas the pressure acting on the upper surface will be ambient pressure. This difference in pressure will tend to maintain the shutoff plug in sealing relation with the anvil member.

It is also to be understood that the drill string pipe section connections are not easily severable by the apparatus of the present invention, and it is therefore contemplated that a pair of such apparatus may be employed in spaced relation such that one of such apparatus will necessarily be positioned on a nonconnection portion of the drill string.

It will now be seen that all of the above-mentioned objects are accomplished by the invention and the preferred embodiment described and illustrated herein. Other modifications and variations of the present invention are possible in light of the above teachings and it is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

Claims

We claim:

1. A combination pipe shear and shutoff apparatus for use in well operations to sever a pipe string and provide immediate complete shutoff in the event of pipe string rupture, comprising:

a housing defining a work chamber and including a through bore for receiving a pipe;

carrier means slidably mounted in said work chamber for movement transverse to said pipe;

pipe-shearing means including blade means carried by said carrier means to effect cutoff of said pipe;

a shutoff plug carried by said carrier means in a direction transverse to said pipe into an operative position;

means axially urging said shutoff plug into sealing relation with said housing through bore when in the operative position; and

actuating means for selective movement of said pipe-shearing blade means and said shutoff plug.

2. The apparatus of claim 1 wherein said means axially urging said shutoff plug into sealing relation with said housing through bore comprises ramp means carried by said housing within said work chamber in the path of slidable movement of said shutoff plug and said plug includes complementary ramp surfaces whereby transverse sliding movement of said plug into sealing relation with said chamber through bore.

3. The apparatus of claim 1 wherein said actuating means comprises an actuator housing defining a cylinder, a piston slidably mounted in said cylinder and in operative engagement with said carrier means, a high-pressure fluid source in fluid communication with said piston cylinder, and valve means for selectively controlling fluid flow to and from said piston cylinder.

4. The apparatus of claim 1 wherein said pipe-shearing means additionally includes annular anvil means fixedly supported by said housing and at the periphery of said through bore.

5. The apparatus of claim 1 wherein said shutoff plug, after cutoff of said pipe, is in sealing relation with said housing through bore portion receiving that section of the pipe extending away from a wellhead, the other through bore portion receiving that section of the pipe connected to the wellhead, whereby said shutoff plug surface in sealing relation is exposed to ambient pressure when said pipe section extending away from the wellhead is ruptured and the opposite surface of said shutoff plug is exposed to well fluid pressure thereby urging said shutoff plug into further sealing relation with said housing through bore.

6. The apparatus of claim 1 wherein said shutoff plug comprises a substantially cylindrical solid metallic body having an axis substantially parallel to the axis of said housing through bore and carries an annular sealing member for engagement with said annular anvil means when said shutoff plug is in the operative position.

7. The apparatus of claim 1 wherein said housing includes longitudinally extending tracks disposed transversely to said pipe and within said work chamber for slidably supporting said carrier means, and longitudinally extending guide ways substantially parallel to said tracks and within said chamber disposed on opposite sides of said carrier means.

8. In a combination pipe cutoff and shutoff apparatus for use in well operations for severing a pipe having a longitudinal axis, the combination of:

a housing having an internal chamber disposed laterally of said pipe axis and having a through bore extending along said axis for receiving a portion of said pipe in said chamber;

carrier means guidably mounted within said chamber in a zone transverse to and at one side of said axis for cutting said pipe and sealing said through bore by movement of said carrier means in one direction in said zone;

said carrier means including a fixed cutting edge and a shutoff plug behind said fixed cutting edge and movable relative to said carrier means in the axial direction of said pipe;

and actuating means for said carrier means whereby movement of said carrier means in said one direction is adapted to cut said pipe portion within said chamber and to immediately thereafter move said plug to seal said through bore.

9. An apparatus as stated in claim 8 wherein said internal chamber includes a chamber portion on the opposite side of said axis for receiving said fixed cutting edge on said carrier means and the crushed severed end of said pipe.

10. An apparatus as stated in claim 8 including cam means on said housing engageable by said plug during movement of said carrier means to move said plug into sealing relation with said through bore.