DE1925912A1 - Method and apparatus for establishing a connection between a watercraft and a wellhead assembly located at a considerable depth of water - Google Patents

Description

Method and apparatus for establishing a connection between a watercraft and a wellhead assembly arranged in a considerable depth of water.

The invention relates to methods and apparatus for use in lowering, finishing and Rework of deep boreholes to be drilled underwater near the coast for the extraction of Ul and gas. More precisely, The invention relates to methods and devices for establishing a connection between a floatable vehicle, that is in one position above a deep well and one on the seabed or in a substantial one The depth of the wellhead located below the surface of the water.

In order to find new oil fields, one is constantly increasing volume of underwater deep boreholes near the coast created j this applies, for example, to the coastal areas of the American States of California, Louisiana, and Texas. Usually extend the casing or casing strings in such deep boreholes together with an or several pipe strings arranged therein up to a point above the water surface where the pipe strings similar to wells drilled on land are plugged in a known manner, and where at the top

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of the casing string a wellhead assembly is known Art is attached. With these arrangements there is a hazard to shipping, and therefore are in recent times Methods and devices have been developed that make it possible to create and complete deep boreholes, wherein both the casing head and later the wellhead assembly and the device for closing the casing be arranged under water at such a depth that watercraft are safely above the deep borehole can move. Such underwater structures are naturally exposed to the corrosive effects of seawater and exposed to the presence of living things that tend to cling to the metal parts of the structure underneath settle on the surface of the water and form incrustations.

As from time to time it may be necessary to have a It is necessary to make already completed deep boreholes accessible again in order to carry out maintenance or rework Desirably, a subsea wellhead design is available to have which is designed so that a connection can be made with the interior of the borehole, or that alternatively at least a part of the underwater construction can be released and brought to the surface of the water to carry out maintenance work.

Since such underwater structures are often arranged in such a water depth that they are not for divers are achievable, various methods and devices have already been proposed which should make it possible in Remotely operated to establish a connection between such an underwater structure and a watercraft, so that the necessary rework can be carried out. A procedure that is widely used is a wellhead fitting with the help of a pipe string or an underwater standpipe lowered from the vehicle and anchored to the subsea wellhead assembly. By doing

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Subsea standpipe may include tubing portions that are disposed with similar tubing portions within the wellhead assembly and / or the casing so that the desired work can be carried out. In the patent (patent application cw »v ^ 4t ^« "joj;

our sign 1A-56 240) is an appropriate arrangement for Establishing a connection between a subsea standpipe and a wellhead assembly described, the can be used when carrying out work of the type mentioned above.

One of the difficulties encountered in attempting to remotely operate a wellhead fitting to attach to an underwater structure consists in the fact that it is not only necessary to carry out this operation from a vessel, in some cases at a height of several a hundred meters above the mouth of the borehole floating on the water, but that the watercraft 'together with the underwater standpipe suspended thereon moves up and down, so that it is difficult to get the standpipe and the connecting device to bring into the correct position in relation to the fixed structure at the mouth of the borehole. For example, a sudden downward movement of the vehicle, caused by a wave or some other effect on the surface of the water during the work mentioned kinking of the standpipe or damage to the underwater structure and / or the connection device.

The main object of the invention is now to provide methods and devices that allow it to be regulated Way, enable remote control connection between a subsea wellhead structure and to manufacture an underwater standpipe assembly, the latter one connection device and one from the watercraft underwater pendulum standpipe includes, and

Take measures to establish such a connection regardless of the up and down movements of the vehicle. Furthermore, the invention provides methods and devices which enable an underwater standpipe assembly with a connection device and an underwater standpipe to be pulled down from a watercraft from which the standpipe assembly hangs down in a controlled manner, so that the distance between the standpipe assembly and the subsea structure during

a certain stage of pulling down, essentially regardless of the up and down movements of the vehicle remains constant.

For this purpose, the invention provides a device which makes it possible to remotely operate an underwater standpipe assembly, that hangs from a watercraft to connect to an underwater assembly, and which comprises a resilient support device disposed on the vehicle by means of which the underwater standpipe assembly is biased essentially upwards with a force which is greater than the weight of the Subsea standpipe assembly. On the vehicle a pulley comprehensive arrangement is provided through which the Up and down movements of the vehicle are compensated, and also when actuating one of their associated The rope used to pull the assembly down is used to secure the underwater standpipe assembly contrary to the upward force exerted by the resilient support in Bring engagement with the underwater assembly.

The invention and advantageous details of the invention are illustrated below with reference to schematic drawings explained in more detail using an exemplary embodiment.

Fig. 1 is a shortened side view showing the lower part of a watercraft on which one is not yet associated with a subsea wellhead structure

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Underwater standpipe assembly is suspended.

Pig. FIG. 2 shows, in an enlarged section from FIG Device for pulling down the assembly and compensating for the movements of the vehicle.

3 shows, in an enlarged side view, part of a clamp and pulley arrangement which is a component the arrangement of FIG. 2 forms.

4 and 5 illustrate schematically the mode of operation of the movement compensation device according to the invention with upward and downward movements of the watercraft ο

According to FIG. 1, any suitable vehicle or boat 11 floats on the surface of a body of water 12 and is above a predetermined drilling site or a borehole by suitable position determining devices in its Maintained position, or it is anchored on the seabed 13 by anchors, not shown, connected to anchor ropes 14 and 15. Such facilities can be used when reworking a deep borehole at a water depth of about 30 to 500 m or more must be carried out. The vehicle 11 is equipped with a derrick 16 of a known type as well Equipped with other known auxiliary equipment that is required to carry out reworking on a deep well and e.g., a turntable 17 '', a lifting device, etc. The derrick 16 is preferably but not necessarily located on a raised platform 18 overlying a slot or a Opening 20 is supported by a frame structure 19. When using a device according to the invention and the application of the method according to the invention can Slot 12 can either be located in the center of the vehicle or extend inward from one side of the vehicle extend. However, it is also possible to carry out the work in question over a side wall of the vehicle 11, i.e. without

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Use a slot to perform. e.g. from a part of the work platform that protrudes beyond one end of the vehicle.

The one in Pig. 1, designated as a whole by 21 Subsea wellhead structure includes a base plate 22 disposed on the seabed 13 which is attached to a Riser pipe or a large diameter Liner 23 is attached which extends downwardly into a pre-drilled deep well and preferably is cemented into this. For a purpose to be explained, two are perpendicular to the base plate 22 upwardly extending guide columns 24 and 25 attached between in which a production wellhead assembly 26, formed in a generally known manner, is disposed. These Assembly 26 comprises at least one production pipeline connected by a coupling to subsea pipeline 26b 26a. The assembly 26 is through a wellhead connector 27 in operative communication with the casing 23 held. At the uppermost part of the assembly 26 is an elongated guide pin with its lower end or an inlet line 28 firmly connected. From the inlet line or the guide mandrel 28 protrudes radially to the outside a fastening block 29 'to which a single guide column 30 projecting vertically upward is fastened.

At the upper end of the individual guide column 30 is a single one extending upwards to the vehicle 11 Fixed guide rope, which can be permanently connected to the column 30 or thereon with the aid of a locking device can be attached, which previously with the aid of a device operated from the vehicle 11 in engagement with the column 30 has been brought; for example, a specially designed device can be used for this purpose Apparatus for locating and locating the wellhead assembly such as a television camera and / or Sound location device, using a pipe string from

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lower a vehicle to the wellhead assembly, to anchor a locking device and an attached guide rope to the column 30. As already mentioned, however, the rope 31 can be permanently connected to the column 30, and grappling hooks or similar devices are used, to initially establish a connection between the free end of the rope and the vehicle. G according to FIGS. 1 and 2 the guide rope 31 runs over a rotatable on an arm 33 mounted pulley 32 and from this to a winch that is firmly anchored on a cover part 35 of the vehicle 11 34 of known construction.

An underwater standpipe 36 hangs from the vehicle 11 down, in which tubing strings 36a and 36b are arranged; this Underwater standpipe is through a hydraulic tensioning device 37 of known type with a predetermined, substantially constant force biased upwards. The in Fig. schematically shown clamping device 37 comprises essentially a housing 38 in which a double-acting hydraulic Piston 39 is mounted, which is firmly connected to the upper part of the standpipe 36. On the piston 39 and thus also on the standpipe 36 is via a .Zuleitung

40 with the aid of a hydraulic pressure medium an essentially constant upward pressure applied. With the line 40 and a corresponding line

41 near the upper end of the housing 38 is a hydraulic accumulator arrangement, not shown, of a known type Kind in connection to keep the upward force at a substantially constant value. It should be noted that instead of the hydraulic clamping device just described to generate an upward force other devices such as a counterbalance arrangement can also be used.

According to Fig. 1 is with the lower end of the standpipe a wellhead fitting 42 of any suitable type. The connecting device 42 is so dimensioned and with a bore of such a diameter

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provided that they rest on the mandrel 28 of the wellhead assembly 26 can be pushed open, whereby a seal to the outside is effected »d. If necessary, with the connection device 42 through a frame structure guide

■ rope fasteners connected to the laying of guide ropes 43 and 44 between the vehicle 11 and the subsea wellhead structure 21

. possible. These devices for securing the guide ropes do not form part of the invention, however they are shown here for the sake of clarity. It should only be noted that these devices have cylindrical shapes Housing parts 45 and 46 include, in which anchoring parts 47 and 48 are mounted freely movable. The anchoring parts 47 and 48 are held in their position shown in Fig. 1 that the guide cables 43 and 44 of the vehicle 11 from with the help of lifting devices 49 and 50 below be kept at a constant voltage. The lifting devices 49 and 50 for applying this constant tension can be of any construction and designed in such a way that they exert tensile forces on the guide ropes 43 and 44 Apply to components of the anchoring parts 47 and 48 forming funnel-shaped components 51 and 52 in contact with the lower ends of the cylindrical housing parts 45 and 46 to keep. It should be noted that the lifting devices 49 and 50 can be made ineffective, so that the anchoring parts 47 and 48 fall freely within the cylindrical housing parts 45 and 46. This is briefly described here Arrangement is described in further details in the patent application mentioned at the beginning. As already mentioned, however, the devices for connecting the guide ropes do not form an object of the present invention,

According to FIG. 1, the connecting device 42 is a Guide housing 53 connected to a through hole through a frame structure. The single guide rope 31 extends through the bore of the guide housing 53,

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around the connection device 42 and other associated devices during their lowering from the vehicle 11 stabilize out. This work is explained in more detail below.

According to FIGS. 1 and 2, the rope 54 used for pulling down is connected by a fastening part 55 to a projection 56 which projects outwardly with respect to an upper section of the underwater standpipe 36. The rope 54 runs on a pulley 57 through _s which is rotatably supported at a predetermined distance below the shoulder 56 over the single guide cable 31st While any suitable device could be used to connect the pulley 57 to the individual guide rope 31, the use of a hydraulic clamping device is preferred because this offers the advantage that an operator can attach the pulley 57 to any desired portion of the individual guide rope at any time 31 can connect, and that the applied hydraulic pressure ensures that the individual guide rope 31 is reliably gripped by the clamping device. An embodiment of a hydraulic clamping device 58 suitable for this purpose is shown in FIGS. Such devices are known and therefore a further description is unnecessary. It should only be noted that the clamping device 58 comprises clamping or jaw parts 59 and 59 which are movable relative to one another and which can be brought into firm contact with the individual guide cable 31 by supplying a hydraulic pressure medium via lines 61 and 62.

Beyond the pulley 57, the rope 54 used for pulling down runs upwards and over another pulley 63, which is rotatably mounted on the free end of the arm 33, and from there on the cover part 35 of the vehicle 11 arranged lifting device or a power-operated Winch 64. The arm 33 is firmly connected to the piston rod 65 of a hydraulic piston, in one of the working

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Platform 18 attached cylinder 66 works ₀ On the cylinder 66, a hydraulic accumulator 67 is attached, which is connected in a known manner to the interior of the cylinder that the piston rod 65 is biased upward to a predetermined tensile force both on the pulley 32 running individual guide rope 31 as well as on the rope 54 running over the pulley 63 and serving for pulling down.

4 and 5 schematically illustrate the mode of operation the device described above. Fig. 4 shows the relative position of the various parts of the according to the invention Device in the event that the vehicle 11 is under the action of waves or other influences assumes its lowest position, i.e. when the vehicle is in its smallest distance from the subsea wellhead structure 21 is located. In contrast, FIG. 5 shows the vehicle 11 in FIG its highest position, at which there is a maximum distance between the vehicle and the wellhead structure 21 is. It should be noted that, in both cases, the wellhead fitting 42 is substantially through the same distance marked X from the wellhead construction 21 is separated. This is primarily due to the fact that the above-described, the piston part '65, the cylinder 66 and the accumulator 67 comprising Arrangement works essentially as a pneumatic spring, which allows the arm 33 to move against the Cylinder 66 to move outward or inward, that arrangement holds the individual guide rope 31 on regardless the upward and downward movements of the vehicle 11 are constantly tense, the piston part 65 being in the cylinder 66 reciprocated to compensate for these movements of the vehicle. Any specific point, e.g. point A on the individual guide rope 31 »therefore retains relative to the sea floor 13 its position essentially unchanged. tie already described, the pulley 32 are for the individual

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Guide rope 31 and pulley 63 are both rotatably mounted on arm 33. Therefore, a certain point, e.g. the Point B on the rope 54 serving for pulling down between the rope pulley 63 and the rope pulley 57 is essentially a unchangeable position both with respect to point A on the guide rope 31 and also with respect to the seabed 13 then occupy when the vehicle 11 moves up or down.

Since the pneumatic force applied to the piston part 65 is somewhat greater than that acting on the piston 39 Force, the underwater standpipe 36 retains its position opposite the sea floor 13, while upward and downward movements of the vehicle relative to the vehicle. Therefore, the one at the bottom of the standard is 36 suspended connecting device 42 despite the movements of the Vehicle 11 at a substantially fixed distance X from the subsea wellhead assembly 21 held. When the connector 42 and standpipe 36 onto the wellhead assembly 21 should be released, winch 64 on the vehicle 11 iam actuates the pull-down button Rope 54 to be hauled in. Since the pulling force of the winch 64 is greater than that applied by the piston 39 to the standpipe 36, force acting upwards, the standpipe 36 and the connecting device 42 are pulled downwards until initially the guide housing 53 (Fig. 1) on the individual

Guide pillar 30 is pushed on. When lowering further of the standpipe 36, the connection device 42 is pushed onto the guide mandrel 28 of the wellhead assembly 21. The single guide pillar 30 and the guide housing 53 are preferably provided with an orientation device (not shown), for example with slots includes cooperating guide pins to ensure that the connecting device 42 assumes the correct position relative to the guide mandrel 28 before these parts engage be brought together. Such a device

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is described e.g. in the patent application mentioned at the beginning. As this device is not an object of the present Forms invention, a more detailed description should be superfluous.

After the wellhead fitting 42 has passed known anchoring devices on the muck 28 has been attached, the tension of the guide ropes is increased and 44 removed, so that the anchoring parts 47 and 48 fall down and slide onto the guide pillars 24 and 25, a solid connection between the guide pillars and the ropes 43 and 44. As already mentioned, this feature is also not an object of the present invention Invention, and it has been described only for the convenience of understanding the invention.

Patent claims:

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Claims (9)

PATENT CLAIMS 1. A device that enables a remote operation to connect an underwater standpipe assembly suspended from a vehicle floating on the surface of a body of water to a wellhead assembly attached to a well casing head above the ground underwater, the assembly being a underwater standpipe and a terminal device comprises, in the fixed to the upper part of the lower water level pipe (36) by a fixed to the floating ^s vehicle (11) resilient support (37) "and serves to the underwater standpipe assembly (36 '42) substantially biasing upward with a force exceeding the weight of the subsea standpipe assembly, a first pulley (57) "means to support the first pulley at a substantially fixed distance from the wellhead assembly (21), a second supported on the floating vehicle Rope pulley (63) and one that is used to pull down Cable (54), one end of which is attached to the underwater standpipe and the other end of which is connected to a first cable winch (64) arranged on the floating vehicle, the cable used for pulling down cooperating with the first cable pulley and the second cable pulley, so that a Actuation of the first winch causes the subsea standpipe assembly to be pulled downward against the force applied by the resilient support to engage the connector (42) with the wellhead assembly. 2. Device according to claim 1, characterized in that g e k e η η, that on the floating vehicle (11) a device is arranged to a substantially fixed distance (X) between the connecting device (42) and 9 0 9 8 49/0923 of the wellhead assembly (21) regardless of the upward and downward movements associated with the floating vehicle can be communicated by the action of waves and other processes on the surface of the water. 3. Apparatus according to claim 1, characterized in that the device for supporting the first pulley (57) is attached to the wellhead assembly (21), up to the floating vehicle (11) extending guide rope (31) and a device (58 ), by means of which the mounting of the first pulley ψ can be braced with the guide rope, so that the first pulley is firmly connected to the guide rope at a certain point and is rotatably mounted. 4 · Device according to claim 3 »characterized in that on the floating vehicle (11) a third pulley (32) is mounted, and that the guide rope (31) cooperates with the third pulley and is connected to a second winch (34 ·) arranged on the floating vehicle. 5. Apparatus according to claim 4, characterized in that g e k e-nnzeich that the second pulley (6.3) and the third pulley (32) are both rotatably mounted on a reciprocating device (33) and together can perform uniform linear movements, and that the device can be moved back and forth by a pretensioning device is pretensioned to a constant even tension in the serving for pulling down rope (54) and to maintain the guide rope (31). 6. Apparatus according to claim 5> characterized in that the resilient support (37) and the biasing device each comprise a hydraulic cylinder and piston assembly (37, 39; 65, 66, 67). 909849/0923 7. Apparatus according to claim 1, characterized in that the rope used for pulling down (54) is attached to the underwater standpipe (36) at a distance from the wellhead assembly (21) which is greater is than that provided by the first pulley (57) between the lower end of the stand pipe and the wellhead assembly maintained substantially fixed distance (X). 8. Apparatus according to claim 7, characterized in that the serving for pulling down Rope (54) extends downward from the underwater standpipe (36), passes under the first rope pulley (57), extends upwards, runs over the second pulley (63) and cooperates with the two pulleys. 9. Procedures that enable them to act by way of fraud one at a floating on the surface of a body of water Vehicle suspended subsea standpipe assembly to a wellhead assembly located above the In the ground underwater is attached to a well casing head, the assembly being an underwater standpipe and a connector, characterized in that the underwater standpipe assembly is brought into position above the wellhead assembly that the subsea standpipe assembly by deposition an upward force of predetermined magnitude is resiliently biased upward that a substantially fixed distance between the connector and the wellhead assembly is sustained without concern for the upward and downward movements of the vehicle which the Vehicle can be notified by the action of waves or other occurrences on the surface of the water by the TX underwater standpipe assembly is moved relative to the vehicle, and that the connecting device is thereby in engagement with the Wellhead assembly is brought onto the subsea standpipe assembly a force that exceeds the upward force, downward force is applied. 09849/0923
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