DRILLING VESSEL AND METHOD FOR OPERATING A DRILLING VESSEL ADAPTED TO RUN LARGE DIAMETER CASING STRINGS

Abstract

The present invention relates to a method for operating a drilling vessel adapted to run large diameters surface casing joints having a diameter of over 20 inch (51 cm) and a length of 30-50 feet (9-15 meters), and build a surface casing string. According to the invention three or more surface casing joints are interconnected into pre-assembled surface casing stands having a length of over 100 feet (30 meters). These surface casing stands are substantially horizontally stored and transferred by a casing stand handling system to a surface casing string handling capacity hoisting device, which subsequently lowers the surface casing string.

Claims

1. A method for running surface casing from a drilling vessel adapted to handle large diameter surface casing joints having a diameter of over 20 inch (51 cm) and a length of 30-50 feet (9-15 meters), and build a surface casing string from said joints, comprising the step of using a drilling vessel which is provided with: a deck with a surface casing stand storage; a casing stand handling system comprising a crane and a catwalk machine; a surface casing string handling capacity hoisting device having a surface casing string lifting tool connectable to a surface casing stand; and a surface casing string hanger, wherein the method comprises the steps of: a) interconnecting, on said vessel, three or more surface casing joints having a diameter of over 20 inch (51 cm) and a length of 30-50 feet (9-15 meters) into pre-assembled surface casing stands having a length of over 100 feet (30 meters); b) storing the pre-assembled surface casing stands in the surface casing stand storage in a substantially horizontal position; c) operating the casing stand handling system to transfer a pre-assembled first surface casing stand from the surface casing stand storage to the surface casing string handling capacity hoisting device; d) connecting the casing lifting tool to said first surface casing stand; e) lifting said first surface casing stand such that the first surface casing stand is suspended from said surface casing string handling capacity hoisting device in a firing line; f) operating the surface casing string handling capacity hoisting device to lower the first surface casing stand in said firing line; g) temporarily holding the lowered first surface casing stand in the firing line by the surface casing string hanger and disconnecting the first surface casing stand from the casing lifting tool; h) repeating steps d)-f) for a second pre-assembled surface casing stand; i) aligning the second surface casing stand above the first surface casing stand; j) interconnecting the second surface casing stand and the first surface casing stand to form a surface casing string; k) releasing the surface casing string from the casing string hanger; l) lowering the surface casing string over the length of the second surface casing stand by the casing lifting tool; m) temporarily holding the surface casing string in the firing line by the surface casing string hanger and disconnecting the surface casing string from the casing lifting tool; n) repeating steps d)-f) and i)-l) for a third pre-assembled surface casing stand.

2. The method according to claim 1, wherein the drilling vessel is provided with a casing pre-assembly installation in which step b) is performed.

3. The method according to claim 1, wherein the drilling vessel is provided with a surface casing storage adapted to store therein multiple surface casing joints, distinct from the surface casing stand storage.

4. The method according to claim 1, wherein the casing stand handling system is adapted to transfer the pre-assembled surface casing stands between the casing pre-assembly installation and the surface casing stand storage.

5. The method according to claim 1, wherein in step b) three or more vertically oriented surface casing joints are interconnected into surface casing stands.

6. The method according to claim 1, wherein in step b) three or more horizontally oriented surface casing joints are interconnected into surface casing stands.

7. The method according to claim 1, wherein the drilling vessel comprises a hull having a moonpool and a main deck and a tower arranged at said moonpool, wherein the surface casing string is lowered relative to said tower through the moonpool.

8. The method according to claim 1, wherein the tower is a mast and wherein the firing line is provided parallel to and outside of a first side of the mast.

9. The method according to claim 1, wherein the vessel is provided with a second hoisting device having a load attachment device, and wherein the method further comprises the steps of performing drilling operations along a second firing line distinct from the first firing line.

10. The method according to claim 1, wherein the catwalk machine includes: a pair of horizontal catwalk machine rails; an elongated catwalk machine frame having a rear end and a front end; and a skate supported by the frame and movable by a drive motor along the length of the frame between a rearward skate position and a forward skate position, and wherein the method comprises the steps of: positioning the frame over the catwalk machine rails in a rearward loading position; loading a surface casing stand in horizontal orientation onto the catwalk machine in the rearward loading position of the frame; moving the frame over the catwalk machine rails to a forward casing release position; and connecting the surface casing stand to be lifted to the surface casing string lifting tool in the forward casing release position.

Description

[0090] The invention will now be described in more detail with reference to the drawings. In the drawings:

[0091] FIG. 1 shows in longitudinal view a vessel according to the invention,

[0092] FIG. 2 shows a plan view of the aft part of the vessel of FIG. 1,

[0093] FIG. 3 shows schematically a step in a surface casing stand upending process of the vessel of FIG. 1.

[0094] FIG. 1 shows a mono-hull vessel 1 having a hull 2 with a bow 3, a stern 4, and a moonpool 5 that extends through the hull 2.

[0095] The vessel 1 is adapted to perform subsea wellbore related operations involving running large diameter surface casing strings from the vessel. Advantageously, the vessel can also perform other subsea wellbore related operations, e.g. drilling operations, in particular involving a riser string, and wellbore intervention.

[0096] In this example, the vessel 1 has an accommodation topside 6 at the bow 3, including crew quarters and a bridge.

[0097] The vessel 1 has an engine room 7, generally below the accommodation topside, with exhausts 7a extending at the rear of the topside 6, above the topside 6.

[0098] The moonpool 5 has, as is preferred, a rectangular shape with opposed lateral sides, a front side and a rear side.

[0099] A front main deck 8 extends between the moonpool 5 and the topsides.

[0100] A rear main deck 9 extends between the moonpool 5 and the stern of the vessel 4.

[0101] The vessel is equipped with a tower 10, which is, as is preferred, embodied as a hollow construction mast having a top 11 and having a base 12 that is integral with the hull 2. The base 12 extends between sections of the hull on opposed lateral sides of the moonpool 5 and the base 12 is spaced from each of the front side and the rear side of the moonpool, thereby forming a front moonpool area 5a forward of the mast 10 and a rear moonpool area 5b rearward of the mast 10.

[0102] The mast 10 has a front side 10a and an opposed rear side 10b as well as opposed lateral sides 10c, 10d.

[0103] In this example, drill pipe racks, here embodied as carrousel type racks 14, are located adjacent the lateral sides of the mast 10, as is known in the art.

[0104] At the rear moonpool area 5b, the vessel is provided with a working deck 15 arranged above the rear moonpool area 5b. As is preferred the working deck 15 is a mobile working deck, here liftable along the mast 10 to such a height that a blow-out preventer can be brought and held underneath the working deck 15 in raised position thereof at an elevated position relative to the mast 10. In a lowered, operative position, the working deck 15 preferably, as here, is level with the adjacent main deck area 9.

[0105] In view of assembly of a surface casing string along a firing line 20 through the rear moonpool area 5b the vessel is equipped with a casing string hanger 17 that is adapted to temporarily hold and suspend therefrom a surface casing string in the firing line 20 into the sea during the surface casing assembly process. As preferred, this hanger 17 is mounted on the working deck 15. Possibly, the hanger 17 is provided with a gimballing support so as to allow for angular variation between the casing string and the working deck, e.g. due to sea motion of the vessel.

[0106] The vessel 1 has a surface casing string handling capacity hoisting device including a casing string lifting tool 25, visible in FIG. 3, which is movable up and down relative to the tower 10 and that is adapted to connect to a surface casing stand 62 and is embodied to support the weight of a surface casing string in the firing line 20 when released from the surface casing string assembly hanger 17.

[0107] The surface casing string lifting tool 25 here is suspended from a travelling hanger device 26 that is movable up and down along the rear side of the mast 10 along one or more vertical rails 27.

[0108] The hanger device 26 is suspended by one or more cables 28 from a sheave arrangement 29 at the top of the mast, which one or more cables 28 are connected to one or more winches 29a, e.g. arranged within the mast 10 (see FIG. 3).

[0109] It is noted that in the shown embodiment the firing line 20 is outside of the rear side 10b of the mast 10 so that the firing line 20 can be reached without hindrance in the process of upending a surface casing stand from the rear of the vessel.

[0110] The vessel further comprises a casing stand handling system that is embodied to transfer surface casing stands between the surface casing stand storage and the casing handling capacity hoisting device. Advantageously, the casing stand handling system comprises a catwalk machine known per se, which is schematically indicated with reference number 45. The casing stand handling system furthermore comprises a crane, which is not visible.

[0111] Such a catwalk machine 45 is commonly known, and comprises: [0112] a pair of horizontal catwalk machine rails 85; [0113] an elongated catwalk machine frame having a rear end, a front end, wherein the frame is movable over the catwalk machine rails at least in a rearward loading position and a forward casing release position, wherein—in the rearward loading position—a surface casing stand in horizontal orientation can be loaded onto the catwalk machine, and wherein—in the forward casing release position—the surface casing stand to be lifted is connectable to the surface casing string lifting tool 25, [0114] a skate which is supported by the frame and is movable by a drive motor along the length of the frame between a rearward skate position and a forward skate position.

[0115] The drilling vessel further comprises a surface casing storage 60, adapted to store therein multiple surface casing joints 61 having a diameter of over 20 inch (51 cm) and a length of 30-50 feet (9-15 meters). In the shown embodiment, the surface casing storage 60 is provided in the hull of the vessel, adjacent a riser storage hold 40.

[0116] Advantageously, both the surface casing storage 60 and the riser storage hold 40 are provided below the main deck area 9. This allows the provision of a surface casing stand storage 65 on the main deck, as visible in FIG. 3, for storing multiple surface casing stands in a substantially horizontal position, and preferably parallel to a longitudinal axis of the vessel 1. As visible in FIG. 3, the surface casing stand storage 65 is adapted to store therein multiple pre-assembled surface casing stands 62, e.g. at least 25 surface casing stands 62. As is shown here, and as preferred, each surface casing stand 62 consists of four interconnected surface casing joints.

[0117] The surface casing storage 60 comprises one or more surface casing storage racks adapted to store therein multiple surface casing joints 61 in horizontal orientation. Similarly, the surface casing stand storage 65 also comprises one or more surface casing storage racks 63 adapted to store therein multiple surface casing stands 62 in horizontal orientation, e.g. each storage rack 63 being embodied to support a surface casing stand 62 at end portions thereof as well as at an intermediate portion thereof at or near each connection between surface casing joints of the surface casing stand 62.

[0118] In this example the surface casing stands 62 are assembled from four surface casing joints of 45 feet (14 meters), thus having a stand length of 180 feet (55 meters).

[0119] The vessel of the invention is furthermore provided with a casing pre-assembly installation 135, adapted to interconnect three or more surface casing joints 61 into surface casing stands 62 having a length of over 100 feet (30 meters). In the shown embodiment, the casing pre-assembly installation 135 is schematically indicated. It is conceivable that the casing pre-assembly installation is provided on the main deck of the drilling vessel, but alternative locations are also conceivable. Pre-assembly, also referred to as stand building, of surface casing joints may take place horizontally on deck. Alternatively, vertical stand building with a vertically orientated pre-assembly installation is conceivable as well.

[0120] In embodiments, the casing stand handling system is also adapted to transfer the pre-assembled surface casing stands between the casing pre-assembly installation and the surface casing stand storage. This can be performed by a crane.

[0121] In embodiments, the surface casing joints are interconnected in the surface casing stand storage. For example, the surface casing stand storage is provided with welding equipment to interconnect casing joints into casing stands.

[0122] Advantageously, as shown in detail in FIG. 3, the vessel also has a second hoisting device having a load attachment device 30 which is movable up and down relative to the mast at a side 10b opposed from the riser firing line 20, so as to allow for handling of items passing through the other moonpool area along a second firing line 21 distinct and spaced from the first firing line 20 where the surface casing string assembly takes place.

[0123] The second firing line 21 extends through the front moonpool area 5a. Along this firing line 21 primarily drilling operations are performed.

[0124] The second hoisting device is embodied as a drilling drawworks, and is provided with a topdrive 31 suspended from the load attachment device 30 to perform drilling operations. The load attachment device 30 is preferably embodied similar as the travelling hanger device 26.

[0125] A working deck 32 is arranged above the moonpool area 5a and may include a rotary table, iron roughneck machine, etc.

[0126] Furthermore, in FIG. 2 are visible hatches 103, 104 forming the roof of a blow out preventer BOP storage, and a BOP support cart 137 which is displaceable on rails 138 extending between the one or more roof openings (with hatches 103, 104) of the BOP hold on the one hand and a docking station, generally in longitudinal direction of the vessel.

[0127] The vessel 1 is thus capable of assembly of a surface casing string in firing line 20.

[0128] Advantageously, the vessel 1 is also capable of assembly of a riser string in firing line 20. For transfer of the riser string to the other firing line 21 a riser string support cart 35 is provided that is displaceable within the moonpool, e.g. skiddable over rails 36 along the lateral sides of the moonpool 5 (see FIG. 3).

[0129] The vessel has a riser storage hold 40, here as is preferred, within the hull 2 aft of the moonpool 5. The riser storage hold 40 is embodied to store the riser stands therein in horizontal position and parallel to a longitudinal axis of the vessel 1. In FIG. 2 the riser stands are visible to illustrate the location of the hold 40. As will be explained the hold 40 is covered in this design by a roof that is formed by the rear main deck 9 so that in practice the riser stands in the hold 40 are not visible from above.

[0130] The riser storage hold 40 is adapted to store therein, or has stored therein, multiple pre-assembled riser stands 42, e.g. at least 25 riser stands 42. As is shown here, and as preferred, each riser stand 42 consists of two riser sections.

[0131] The riser storage hold 40 comprises one or more riser storage racks 41 adapted to store therein multiple riser stands 42 in horizontal orientation, e.g. each storage rack being embodied to support a riser stand at end portions thereof as well as at an intermediate portion thereof at or near each connection between riser sections of the riser stand.

[0132] In this example the riser stands 42 each have a length of 150 ft. (45.72 m).

[0133] The riser storage hold 40 has a roof 44 formed by the structure of the main deck 9.