Apparatus, system and method for installing and retrieving pipe in a well

This application is a continuation-in-part to U.S. patent application Ser. No. 09/571,134 filed May 15, 2000 entitled “Apparatus, System and Method for Installing and Retrieving Pipe in a Well,” now U.S. Pat. No. 6,250,395, which is related to Provisional Application 60/163,869, filed Nov. 5, 1999. Said applications are incorporated herein for all purposes and the benefit of the earlier filing dates of said application is claimed herein.

The present invention, as with the inventions in the previously mentioned patent applications, relates to apparatus systems and methods for running and storing pipe used in the drilling and completion of wells.

Currently, pipe used in drilling and completing wells is stored in the derrick or stored in racks on the drilling structure. When the pipe is being temporarily removed from the well, it is pulled from the well in stands of three or four joints and stored vertically in the derrick. Going back into the well, the process is reversed.

When using a top drive or traveling block to run pipe in and out of the well, the time required to come out of the well includes the time required to attach to the top of the drill string, pull a stand up above the floor, unthread the stand, set it back in the derrick, and return the top drive or traveling block down to the floor to engage the drill string to pull another stand.

In an invention described in the previously identified patent applications, the pipe used to drill and complete an offshore well is run into and out of the well in a continuous string of jointed pipe sections. The water area surrounding the drilling structure is used to store the pipe in a continuous string or in a series of relatively long string segments. The pipe string is conveyed through a curved guide extending from the drilling rig to the water area adjacent the drilling structure. The radius of curvature of the guide is greater than the minimum permitted non-yielding radius of curvature for the stiffest string of pipe to be used in the drilling or completion of the well.

The large drill pipe used to drill wells in deep water can have a cross sectional diameter of 6 ⅝ inches or larger. A curved guide capable of handling such drill pipe preferably has a radius of curvature of approximately 160 ft. The distance from the point on the drilling rig floor at which the pipe exits the well to the point at which the pipe is redirected back into the water is therefore approximately 320 ft. Very large drill ships have adequate room to accommodate the required 320 ft. spacing between the drilling rig floor and the water entry point. Such is not the case in smaller rigs such as semi-submersible rigs.

The distance from the rotary table to the furthest edge of a semi-submersible drilling structure is typically less than 200 ft. One object of this invention is to adapt the pipe handling system, method and apparatus described in the previously identified applications for use on a semi-submersible rig.

It may be desirable to maintain circulation through the string of pipe stored in the sea. It may also be desirable to displace the drilling fluid contained within the drill pipe before it is stored in the sea.

Very long strings of pipe inserted into a storage sleeve may require a means for assisting the insertion of the drill string into the sleeve.

It may also be desirable to have multiple strings of pipe stored in the sea with multiple systems available for separately, or simultaneously, supplying the strings to the drilling rig floor. Such is the case, for example, when two completion strings are simultaneously run into the well in what is termed a “dual completion.”

Drilling structures that lack sufficient deck space to accommodate a large bending radius guide are provided with a platform extension to position a work area at the location where the string completes its 180-degree curve and extends vertically into the water. In a preferred embodiment, the platform extension is positioned at one corner of a four-cornered deck of a semi-submersible drilling rig to minimize the length of the platform required to extend to the point of the completion of the drill pipe curve.

Multiple guides may be employed for simultaneously running two strings of pipe. The string may be stored in one or more long sections or in a single continuous string. The major portions of the string or long pipe sections may be stored below the surface of the water. Provision is made for pumping fluids through the pipe string, and/or the pipe sections stored in water, to the well. The string may be stored in a sleeve. A flexible hose attached to the end of the drill string permits pumping of fluids into the well through the string while the string is in the sleeve. An air supply to the sleeve assists in maintaining the buoyancy of the sleeve and its contents. A pulling system is provided to assist in pulling the drill string through the sleeve.

FIG. 1 is a schematic illustration of a semi-submersible rig equipped with a platform extension for accommodating a 320 ft. diameter pipe string curve;

FIG. 2 is a top view of the rig illustrated in FIG. 1;

FIG. 3 is a top view of a semi-submersible rig equipped with multiple curved guides for simultaneous handling of multiple pipe strings;

FIG. 4 is a schematic illustration of a drill string stored in a storage sleeve equipped with fluid circulation through the stored drill string and buoyancy control for the sleeve;

FIG. 5 is a schematic illustration of a drill string equipped with a circulation hose disposed within an optional storage sleeve; and

FIG. 6 is a schematic illustration of vertically racked pipe strings equipped with circulation hoses for pumping into the well.

FIG. 1 illustrates a semi-submersible rig indicated generally at 10 having a platform extension 11 provided at one corner. FIG. 2 illustrates a plan view of the rig illustrated in FIG. 1 . Placing the platform extension 11 at the corner of the rig permits maximum usage of the semi-submersible deck surface. The platform extension 11 is illustrated extending away from the corner of the rig sufficiently to accommodate a curving guide 12 having a radius of curvature sufficient for handling pipe 13 requiring a bending radius of 160 ft. Guide supports 14 , 15 and 16 hold the guide in position as the pipe is moved between a drilling rig floor 17 through a mast 18 to a work area mast 19 .

FIG. 3 illustrates a platform extension 20 formed on the side of the drilling structure 21 and illustrates the use of two guides 25 and 26 for simultaneously handling two separate strings 27 and 28 . A drill string or completion string 27 and a completion string 28 are illustrated extending from the water area 30 adjacent the drilling structure 21 and through the guides 25 and 26 to the drilling rig. The use of multiple guides permits drilling and/or completion operations to be conducted simultaneously and speeds the conversion between running the drill pipe and running the completion string or other type of work string. Thus, a string of drill pipe may be moved through one guide to permit the well bore to be drilled in one well and a string of tubing may be simultaneously moved through another guide to conduct a completion operation in another well being completed from the same drilling structure. Similarly, two drill strings may be simultaneously moved in the multiple guides to drill two separate wells. Dual completions are also made possible with the multiple guides. In a dual completion, two tubing strings may be simultaneously run in two separate guides to install two tubing strings in a single well. There are other occasions where it may also be desirable to have multiple strings of pipe stored in the sea with multiple systems available for separately, or simultaneously, supplying the strings to the drilling rig floor. Multiple guides and pipe drive systems also permits one system to be used while the other system is being serviced or repaired.

FIG. 4 illustrates a system indicated generally at 40 used to provide circulation through a drill string 41 stored within a storage sleeve 42 submerged in the sea 43 . A flexible hose 44 is supplied with fluid pressure to circulate mud through the far end 45 of the drill string and back into the well bore to provide circulation into or from the well. The hose may also be used to displace the mud in the drill string as it is being removed from the well. The flow of the fluid through the hose and drill string may be reversed if desired.

The circulation hose 44 is stored on a hose reel 47 that has sufficient capacity to extend out to the end of the storage sleeve 42 . A suitable mechanism such as the illustrated sprocket 49 is secured to the end 48 of the storage sleeve to feed the hose 44 into and out of the end of the sleeve. A sliding seal 50 positioned about the hose and within the storage sleeve provides a sliding engagement with the hose that prevents seawater from entering into the storage sleeve and prevents fluid within the sleeve from flowing into the sea. The hose and reel also function as a mechanism for pulling the drill string through the storage sleeve toward the end 48 of the storage sleeve. If desired, the sprocket may have a rotary power supply 52 providing motive power to directly pull the hose and drill pipe through the sleeve.

A flotation system 55 maintains the storage sleeve at a desired location below the water surface. An additional flexible hose 56 may be included to supply flotation air to the sleeve. The flotation air is injected into the sleeve at a point 57 between the sliding seal and the surface entrance 58 to the storage sleeve causing the water density in the sleeve to be reduced to the point required to allow the sleeve and its contents to achieve positive buoyancy. The flotation air may also be employed to positively displace water from the storage sleeve to attain the desired buoyancy.

FIG. 5 illustrates a form of the invention, indicated generally at 60 , in which the circulation hose is attached to the end 61 of the pipe 62 before the pipe is run into the sea. The end of the hose and the end of the drill pipe are connected together to provide communication between the end of the drill pipe and the hose. The drill pipe and attached hose may be inserted into a storage sleeve 63 if desired. As with the previously described embodiments, circulation may be established between the mud system and the drill pipe 62 through the hose. A flotation system 65 is employed to maintain the drill pipe and attached hose at a desired depth below the water surface. The flotation system is attached to the sleeve when the sleeve is used.

When a storage sleeve system is employed, the far end of the sleeve 66 may be looped back to the drilling structure with the circulating hose being supplied from the outside of the sleeve at the far end of the sleeve. In this embodiment, which is similar to that illustrated in FIG. 4, the storage sleeve will loop from the drilling structure out into the sea and back to the drilling structure forming a large circular path. This embodiment minimizes the amount of hose required to connect between the drilling structure and the end of the drill pipe. In operation, before the drill pipe is introduced, the hose is fed from one end of the tube to the other, beginning from the exit end 66 of the sleeve and advancing to the entrance 68 to the sleeve at the work area 70 . Before the drill pipe is introduced into the entrance to the sleeve, the hose contained within the sleeve is connected at its end, at the entrance to the sleeve, to the free end of the drill string extending from the curved guide into the work area. Once the hose is attached to the end of the drill string, circulation flow can be established from the pumping system on the drilling vessel. The circulation path is from the pumping system, through the hose reel 71 , through the circulation hose as it extends through the sleeve in the sea, through the drill string and down the drill string into the well. As the drill pipe is pulled from the well and advanced into the sleeve, the reel takes up the hose coming from the exit end of the sleeve. The reel may also assist in pulling the hose and attached drill pipe through the sleeve. The hose may be equipped with an integral cable or other strong tension structure that permits it to exert a strong pulling force on the drill string.

FIG. 6 illustrates a technique for hanging off continuous lengths of jointed pipe from the drilling structure, such as indicated at 80 . The bottoms 81 and 82 of the pipe strings are connected with flexible hoses 83 and 84 that are supplied with pressurized fluid from the pumping system. The work area platform 85 provides a rack or support structure 86 from which the stands may be supported. One stand 80 is illustrated supported from the work area platform. A second stand 87 is being moved through the curved guide 88 either into racking position or from the racking position to the well. As this movement occurs, the flexible hose 84 can continuously supply pressurized fluid to maintain circulation in the well or to displace fluid from the drill string. The water depth limits the length of the stands supported from the work platform. A remotely operated release may be provided for the hose connectors 89 and 90 to permit removal of the hoses from the end of a racked stand. The released connectors 89 and 90 may be retrieved to the support platform for use with the next stand to be racked.

While preferred forms of the present invention have been described in detail herein, it will be appreciated that many variations in the apparatus, methods and systems described may be made without departing from the spirit or scope of the inventions.