Expandable drilling template system

Abstract

A template that can be used for drilling subsea wells in proximity at the seafloor is provided. The template is first placed over an existing protuberance above the seafloor, which is usually the conductor casing of an existing well. The template has a plurality of cans or guide slots, of which one has a J-slot that can be engaged by a running tool. The template is placed near the seafloor and plates are released to rest on the seafloor and support the template. After wells are drilled through the slots, the template can be rotated or moved to additional well casings for the drilling of additional wells.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention pertains to subsea wells. More particularly, a template for drilling wells on the seafloor and apparatus and method for placement of the template are provided.

[0003] 2. Description of Related Art

[0004] Offshore oil and gas well drilling is usually conducted by placing multiple wells in close proximity where they penetrate the seafloor. To assist in placing the wells at a known location closely spaced, a drilling template is usually employed. The template is used for guiding drill strings, tubulars and tools into the seafloor. Templates may be placed directly on the seafloor and held in place by their mass or they may be affixed to piles or other equipment. Submerging or uneven settling of templates has caused problems in some areas.

[0005] U.S. Pat. No. 4,706,757, discloses a template that is supported by a wellhead. A central support member of the template engaged with the wellhead is supported above the seafloor. A number of guide slots are attached to the central support member, which may be prevented from rotating on the wellhead. The central support member fits coaxially over the upper portion of the wellhead. In one embodiment, a running tool is used to install the template, with J-slots engaging lifting dogs on the central support member. The running tool is cylindrical and fits over an upper portion of the central support member.

[0006] U.S. Pat. No. 5,244,312, discloses a method for installing a drilling template that is supported on preset piles. The template is leveled while supported on the piles. U.S. Pat. No. 4,784,527 discloses a modular template. In one embodiment, the template is secured to the seafloor by piles and is leveled by adjustment of gimbaled jack mechanisms associated with individual latches.

[0007] What is needed is a versatile template system that can be used to drill closely spaced wells on the seafloor and that can be deployed and re-positioned simply to allow drilling of a selected number of closely spaced wells, thereby effectively making the template expandable.

SUMMARY OF THE INVENTION

[0008] A template having guide slots or cans supported in a frame is provided. In a preferred embodiment, the template is first placed over casing of an existing well on the seafloor. Leveling plates attached to rods are placed on the seafloor when rod guides release and then re-grip the rods. Devices on the template can determine if it is horizontal. A running tool that can be attached to drill pipe and is sized for attaching to the template by a J-mechanism is also provided. A TV camera can be placed in the running tool and used, along with a jet sub, to place the template. A gyroscope can be used to determine compass direction of the template. The template can be rotated around the original well and can be moved to other well casings to drill additional wells.

BRIEF DESCRIPTION OF THE FIGURES

[0009] FIG. 1 is a top view of the disclosed subsea template.

[0010] FIG. 2 is an elevation view of the disclosed subsea template.

[0011] FIG. 3 is a detailed view of a rod guide and leveling plate assembly of the disclosed template.

[0012] FIG. 4 is an elevation view of a running tool for placing a subsea template disclosed herein on the seafloor with drill pipe.

[0013] FIG. 5 is a top view of a template before and after re-positioning for drilling additional wells.

DETAILED DESCRIPTION

[0014] A top view of one embodiment of the subsea template disclosed herein is shown in FIG. 1 at 10. Beams 12 form a frame in which cans (or guide slots) 14, 16 and 18 are held in place by cross support members 20. Center can 14 includes top funnel guide 22 and gussets 24. Gussets 24 are sized such as to center can 14 over a protrusion extending from the seafloor, which is normally a conductor casing. The sizing of center can 14 including gussets 24 can be adjusted to allow centering of can 14 over a protuberance extending above the seafloor. Cans 16 and 18 are sized such as to allow conductor casing of adjacent wells to be run through the cans. Pad eyes 26 may be placed on frame 12 for use in lifting the template. Preferably, the structure of template 10 is symmetrical with respect to orthogonal planes that extend through the center of can 14. This allows template 10 to be suspended in a horizontal plane when the template is supported only through can 14.

[0015] Leveling plate rod guides 28, 29 and 30 are extended from frame 12 and are used to receive leveling plate rods (not shown) used for leveling and supporting template 10 on leveling plates (not shown). Each rod guide includes a mechanism for controlling movement of leveling plate rods through the rod guide. An enlarged view of one embodiment of such mechanism for rod guides 28, 29 and 30 is shown in the inset below rod guides 30. By applying torque to bolts 33, bracket 31 can be adjusted to control friction on a rod that is sized for passing through the rod guide. Level devices 32 are used for leveling template 10. The levels may be simple devices based on the location of a bubble, which must be observed by a diver or a TV camera, or may be an electronic device.

[0016] Although three cans are shown in template 10, it should be understood that only two cans may be used or more than three cans may be used and the same principles can be applied as described herein. The template should be weight-balanced such that it lies in a horizontal plane when supported. The distance between cans can be adjusted by varying the length of members of frame 12 between the cans. For example, members can be inserted such that the cans have spacings of 7.5 feet, 8.5 feet or 10 feet, which correspond to distances between wells often used on platforms. Other distances may be selected, depending on the design of a structure to be used for drilling through the template.

[0017] Dimensions of can 14 may be as follows: funnel guide 22 may have an outside diameter of 61.5 inches, an inside diameter of 41 inches and a sloping surface 10 inches wide; gussets 24 may have a protrusion distance into the can of 3 inches, a thickness of 0.75 inch and a length of 1.5 feet, with slope angles of 45°. The body of can 14 may have an OD of 42 inches and an ID of 40.75 inches, which provides a diameter within the gussets of 34.75 inches. Cans 16 and 18 may have an OD of 36 inches and an ID of 34.75 inches. These cans would be suitably sized for 30-inch OD conductor casing extending through the cans. Funnel guides on cans 16 and 18 may have an OD of 55.5 inches, an ID of 35 inches and a sloping surface 10 inches wide. Lower funnel guides (not shown) may be added to these cans.

[0018] In one embodiment, distances between cans 14 and 16 are 9 feet center-to-center The overall length of frame 12 is 25.5 feet and the width is 9 feet to the exterior of the frame. Pad eyes 26 may be placed at a distance 5 feet from the ends of frame 12. The frame may be made of 8-inch schedule 40 pipe having a wall thickness of 0.322 inch. The frame and cans may be joined using conventional welding techniques.

[0019] FIG. 2 depicts an elevation view of template 10. Center can 14 has upper funnel guide 22 and lower funnel guide 25. Lower funnel guide 25 is used for guiding center can 14 over a protrusion from the seafloor and upper funnel 22 is used for guiding tubulars or tools into can 14. Center can 14 also includes J-slot 54, which is used in placing template 10 on the seafloor, as will be described below. Frame 12 of template 10 is supported on or near the seafloor by leveling plate rods that pass through rod guides 28, 29 and 30. The rods may be held in place by friction caused by tightening of bracket 31, which is shown in more detail in FIG. 1.

[0020] FIG. 3 shows details of a leveling plate assembly that may be adapted for use in rod guides 28, 29 and 30 of FIGS. 1 and 2. Rod 34 may be placed through the rod guides before template 10 is deployed subsea. The rod may be lifted using eye 35. Leveling plate 38 may be attached to leveling plate rod 34 using pin 39. Leveling plate 38 is stabilized by gussets 40. Leveling plate rod 34 may have a length of 10 feet. Leveling plate 38 may be rectangular in shape with sides of 3 feet and 4 feet, for example. Larger area of a leveling plate is desirable when softer seafloor is expected. Leveling plate rod 34 may be made of 5-inch drill pipe, for example.

[0021] FIG. 4 illustrates running tool 42. Running tool body 44 is sized to be placed over a protrusion extending above the seafloor, such as 30-inch conductor casing. Body 44 of the running tool may have a diameter of 36 inches and a wall thickness of ⅝ inch, for example. Body 44 is attached to tubular support 46, which may be 4½ inch-drill pipe terminating in box 47. Gussets 48 are used in attaching support 46 to body 44. The top of the body is preferably open around the gussets, providing for passage of a TV camera and cable into running tool 42. At the lower end of body 44 are gussets 50, which may have a thickness of about 2 inches in the radial direction and a thickness of about 0.75 inch and a length along the radius of body 44 of about 1.3 feet, for example. Lugs 52 protrude from gussets 50. Normally, gussets 50 are spaced at 90° angles around body 44. Painted stripes 54 may be provided on the inside surface of body 44 to assist a TV camera operator in keeping a camera within the body as the running tool is lowered on drill pipe.

[0022] For this size protrusion, running tool body 44 should have an OD of 36 inches with a ⅝-inch wall. Gussets 50 have a depth of 2 inches, a width of ¾ inch and a length of about 1.5 feet. They may be placed at 45°(90° shown in FIG. 4). Lugs 52 are sized to be used in J-slot 54 (FIG. 2). The lugs may have a diameter of 2.5 inches and a length of 3.5 inches. The running tool gussets then extend to an outside diameter of 40 inches and can be accommodated in can 14, having a J-slot and an inside diameter of 40.75 inches. Lugs 52, having an OD of 43 inches, are accommodated within the 3-inch slot width of J-slot 54.

[0023] The following procedure may be used to place template 10 on a casing or other protrusion from the seafloor. The dust cover on a casing is first removed. A trash cap is then preferably placed on the casing. The height of the casing or other protrusion above the seafloor should be determined so as to insure that the running tool is long enough to go over the protrusion and set a template at the desired height off the seafloor. The template is then moved to the cellar deck on the drilling vessel. Leveling pads including rods 34 and leveling plate 38 are installed in guide sleeves 28 and 30 and, optionally, guide sleeves 29. Running tool 42 may be made up with muleshoe sub 49 for orientation of template 10, using a gyroscope landed in the sub, and jet sub 51, which may be used to force the running tool over the protrusion on which it is to be placed. The J-slot running tool is then placed in center can 14 of template 10 and the template is then lowered on drill pipe to about 20 feet above the mud line. Preferably, center can 14 is observed going over the protrusion, such as a 30-inch drive pipe or casing, with a remotely operated vehicle (ROV) or a diver and by a TV camera suspended on a cable passing into the top of body 44. The template is then preferably lowered to about 3 feet above the mud line. Preferably, a single shot gyroscope is used to align the template in the desired direction by landing the gyroscope is mule shoe sub 49. The alignment may be verified by re-running a single shot gyroscope. Then the template is lowered to tag bottom and leveling devices 33 are checked with an ROV or diver to determine if the template is level. If necessary, the drill pipe and template are raised slowly until the template is observed to be level. At this point, torque is applied to bolts 33 of brackets 31 around the template, using a diver or ROV. This allows leveling pads 38 to drop to the seafloor. Then bolts 33 on each of the leveling pads are re-tightened using a diver or ROV. The drill pipe is then lowered until the J-slot running tool is at the bottom of the “J”. Again the bubble leveling device or devices are checked to determine if the template is level. If it is not, the template is pulled up slowly until the template is level and the leveling pad lock bolts are again released and re-tightened as explained above. After a check of the leveling device with the J-slot running tool at the bottom of the J shows that the template is level, the running tool is then “unjayed” from center can 14 of template 10 and retrieved on the drill pipe. Although the J-mechanism is the common method for attaching and releasing such loads, it is clear that other mechanical mechanisms may be used to achieve the same result.

[0024] The entire apparatus can be conveniently assembled for shipment by clamping legs 34 within frame 12, attaching leveling plates 44 to the bottom of frame 12 and storing running tool 42 on posts 17 that protrude above frame 12. The entire assembly then can be lifted and located using a clevis which is attached to cables and inserted in each pad eye 26 with a pin.

[0025] When more wells are to be drilled from a subsea location than the number of cans in the template, template 10 can be successively rotated or moved from the first wells drilled. Rotation is accomplished by lowering a running tool, such as shown in FIG. 4, on drill pipe with muleshoe sub 49 and jet sub 51 present between the running tool and the drill pipe. Preferably, a TV camera is placed in body 44 of running tool 42 before the running tool is placed subsea. As the running tool is lowered on drill pipe, cable supporting the TV camera is reeled off to maintain the camera within body 44. Preferably, stripes 54 of black and white are placed on the inside surface of body 44 to assist the cable operator in maintaining the camera within body 44. Using the camera to locate body 44 with respect to the J-slot of the can to be engaged by lugs 52 of running tool 42, jet sub 51 can be operated to move body 44 in the direction necessary to place lugs 52 in the J-slot of the can. After the J-mechanism is engaged, drill pipe at the surface is rotated, usually by 90 degrees, to rotate the template. A one-shot gyroscope may then be run through drill pipe to muleshoe sub 49, where a measurement can be made to verify direction of the template after its rotation. Two additional wells can then be drilled from the cans 16 and 18, as shown in FIG. 5. This allows a total of five wells to be drilled using template 10.

[0026] If additional wells are to be drilled in the selected location, template 10 can be lifted off the original well (well 1, which is drilled before template 10 is deployed) using the same technique as described before. Center can 14 can then be placed on one of the wells drilled off the line of the original wells, such as well 5. Wells 6 and 7 (not shown) could then be drilled such that wells 5, 6 and 7 are aligned in the same direction as wells 1, 2 and 3. Similarly, template 10 may be placed over well 4 and wells 8 and 9 (not shown) could be drilled with the same alignment as wells 1, 2 and 3. A jackup platform can usually accommodate nine wells. Template 10 may then be recovered from the seafloor before the wells are tied back

[0027] If more than nine wells are to be drilled, such as from a semisubmersible rig, using techniques described before, template 10 can be placed such that an end can, such as can 16 of FIG. 2, is around well 3, for example. Template 10 can then be aligned in the direction of wells 1, 2 and 3, and the direction verified using a gyroscope. Additional wells can be drilled as described before. Preferably, if more than nine wells are to be drilled, a lower funnel, such as funnel 25 of FIG. 2, is also placed on cans 16 and 18 (not shown) to facilitate lowering of one of these cans over the conductor casing of an existing well.

[0028] Although the present invention has been described with respect to specific details, it is not intended that such details be regarded as limitations upon the scope of the invention, except as to the extent they are included in the following claims.

Claims

1. A drilling template for subsea drilling, comprising:

a plurality of cans supported by a frame and cross-supports, one of the cans having a J-slot therein for support of the template in a horizontal plane and being adapted to be lowered over a selected protrusion extending from a seafloor location;

a plurality of leveling plate rod guides affixed to the frame and a plurality of leveling plate rods, each of the leveling plate rod guides having a mechanism for controlling movement of one of the leveling plate rods through the rod guide; and

a leveling plate affixed to each of the leveling plate rods.

2. The template of claim 1 further comprising a level-measuring device attached to the frame and cross-supports for determining if the frame is horizontal.

3. The template of claim 1 wherein each of the cans adapted to be lowered over the protrusion is adapted by gussets affixed therein.

4. The template of claim 1 wherein the mechanism for controlling movement of the leveling plate rods is a bracket having bolts therein.

5. The template of claim 1 wherein the plurality of cans is three cans.

6. The template of claim 1 further comprising a shipping bracket attached to the frame.

7. A running tool for placing a subsea drilling template, comprising:

a body, the body having an outside diameter and an inside surface and being sized to be lowered inside a selected can of the drilling template, the can having a J-slot therein;

a plurality of lugs attached to the outside diameter of the body, the lugs being adapted to move inside the J-slot; and

a support attached to the body.

8. The running tool of claim 7 further comprising a stripe painted on the inside surface for adjusting the position of a TV camera in the body.

9. A method for placing a drilling template over a protrusion extending above a seafloor location, comprising:

assembling the template, the template having a frame, a plurality of cans including a can adapted for lowering over the protrusion, the can having a J-slot therein, and a plurality of leveling plates attached to a plurality of leveling plate rods, each of the leveling plate rods being attached to the frame by a mechanism to control movement of the leveling plate rods with respect to the frame;

lowering the template with drill pipe, the drill pipe supporting the template by a J-mechanism, to place the can having the J-slot therein over the protrusion with the template a selected distance above the seafloor location;

operating the mechanism to control movement of the leveling plate rods to release the plurality of leveling plate rods such that the plurality of leveling plates rest on the seafloor location;

operating the mechanism to control movement of the leveling plate rods to prevent further movement of the leveling plate rods; and

operating the J-mechanism to release the drill pipe from the template.

10. The method of claim 9 further comprising determining if the frame of the template is in a horizontal plane before operating the J-mechanism to release the drill pipe from the template.

11. The method of claim 9 further comprising operating an orienting device to determine compass orientation of the drilling template.

12. The method of claim 9 further comprising operating a TV camera while lowering the drill pipe.

13. The method of claim 9 further comprising operating a jet sub to assist in the step of placing the can having the J-slot therein over the protrusion.

14. The method of claim 9 wherein the protrusion is a conductor casing of a well.

15. A method for drilling a plurality of subsea wells through a drilling template, the drilling template comprising a plurality of cans supported by a frame and cross-supports, one of the cans having a J-slot therein for support of the template in a horizontal plane and being adapted to be lowered over a conductor casing extending from a seafloor location, a plurality of leveling plate rod guides affixed to the frame and a plurality of leveling plate rods, each of the leveling plate rod guides having a mechanism for controlling movement of one of the leveling plate rods through the rod guide, and a leveling plate affixed to each of the leveling plate rods, comprising:

assembling the template, lowering the template with drill pipe, the drill pipe supporting a running tool having lugs to engage the template by the J-slot, to place the can having the J-slot therein over the conductor casing with the template a selected distance above the seafloor location;

operating the mechanism to control movement of the leveling plate rods to release the plurality of leveling plates and leveling plate rods such that the leveling plates rest on the seafloor location;

operating the mechanism to control movement of the leveling plate rods to prevent further movement of the leveling plate rods;

operating the J-mechanism to release the drill pipe from the template and retrieving the drill pipe;

drilling at least one well through at least one of the cans and placing an added conductor casing therein;

running the running tool with drill pipe and engaging the running tool and the can having the J-slot therein;

rotating the template through a selected angle by rotating the drill pipe;

operating the J-mechanism to release the drill pipe from the template and retrieving the drill pipe; and

drilling at least one well through at least one of the cans and placing an added conductor casing therein.

16. The method of claim 15 further comprising running drill pipe with the running tool and engaging the running tool and the can having the J-slot therein, removing the template from the conductor casing and placing a can of the template not having a J-slot therein on the added conductor casing; and

drilling at least one well through one of the cans.

17. The method of claim 15 further comprising operating a jet sub to assist in the step of placing the can having the J-slot therein over the added conductor casing.