Wells – Processes – Placing or shifting well part
Reexamination Certificate
2000-05-12
2001-12-25
Suchfield, George (Department: 3672)
Wells
Processes
Placing or shifting well part
C166S077300, C226S173000
Reexamination Certificate
active
06332501
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to coiled tubing injectors, and apparatus and methods for combining conventional sectional tubing drilling with drilling using coiled tubing. More particularly, a collapsible mast and rotary table can be arranged for operation with both a catwalk for sectional tubulars and with a coiled tubing unit. A linear coiled tubing injector is sufficiently narrow to coexist in the mast while tripping conventional tubulars.
BACKGROUND OF THE INVENTION
The general background relating to coiled tubing injector units is described in U.S. Pat. Nos. 5,83 9,514 and 4,673,035 to Gipson which are incorporated herein by reference for all purposes.
Apparatus for conventional drilling with sectional tubing is very well known.
Coiled tubing has been a useful apparatus in oil field operations due to the speed at which a tool can be run in (injected) and tripped out (withdrawn) from a well bore. Coiled tubing is supplied on a spool. An injector at the wellhead is used to grip and control the tubing for controlled injection and withdrawal at the well. As coil tubing cannot be rotated, drilling with coiled tubing is accomplished with downhole motors driven by fluid pumped downhole from the surface.
SUMMARY OF THE INVENTION
Linear Injector
In one aspect the linear injector of the present invention extends coiled tubing capability beyond that known heretofore. In combination with a conventional jointed drilling rig, none of the functionality of the conventional rig is sacrificed while achieving enhanced capabilities by the addition of coiled tubing.
In the preferred embodiment, coiled tubing is driven along a linear section of an endless chain conveyor with an opposing linear array of rollers. Using prior art dual conveyors, gripper blocks pull on both sides of the coiled tubing and the present invention only pulls on one side. Applicant has found that by eliminating the prior art parallel chain drives, the difficulty to synchronize the two drives is avoided and the substitution of non-driving rollers for one side of the tubing injector results in less damage to the coiled tubing. Further, by eliminating the challenge of maintaining dual chain synchronicity, the novel injector is able to take unrestricted advantage of an extended length of a linear driving section, thus providing superior injection and pulling capability.
Accordingly, in one preferred aspect of the invention, deep wells can be drilled with coiled tubing even from the surface due to the combination of enabling the use of full diameter tubing, implementing a straightener and using an injector which is capable of applying both significant injector force on a drilling bit and full pulling capability f or tripping out of the deep wells. An injector of 20 feet in length is capable of a nominal pulling capacity of about 100,000 lb. force. Further, suspension of the preferred injector in a conventional derrick having strong draw works and a rotary table permits operation with both conventional sectional tubing, including BHA, and simplifying the making up to coiled tubing.
In a broad aspect of the invention then, coiled tubing injection apparatus is provided comprising:
a chain conveyor extending about an endless path and having at least one linear section aligned with the wellbore;
a multiplicity of gripper blocks conveyed and driven by the chain conveyor, the gripper blocks forming a substantially continuous coiled tubing support while traversing the linear portion;
a linear array of a multiplicity of rollers in parallel and opposing arrangement to the linear section of the chain conveyor for forming a corridor therebetween and through which the coiled tubing extends, the rollers urging the coiled tubing into frictional engagement with the gripper blocks;
means for supporting the gripper blocks against the normal forces produced by the linear array of rollers; and
means for driving the chain conveyor along the endless path so as to drive the gripper blocks which frictionally drive the coiled tubing along the corridor.
Preferably idlers extend laterally from the gripper blocks for rolling along a track, thereby supporting the normal forces on the chain conveyor. More preferably, biasing means are provided for adjusting the normal force imposed by the rollers against the coiled tubing. Further, a tubing straightener is positioned between the apparatus and a source of coiled tubing, just preceding the corridor between the linear portion of the gripper blocks and the linear array of rollers.
In another embodiment, the linear injector can be pivotally mounted to a mobile transport for aligning the linear injector with wellheads at any angle to the surface.
In another aspect, the present invention utilizes a combination of apparatus which borrows the best of both the conventional and coiled tubing drilling apparatus for providing improved efficiency in drilling operations. Both the conventional and coiled tubing art is improved to permit even deep wells to be drilled using coiled tubing. While conventional coiled tubing injectors could be used, they must be narrow enough to standby in the mast while sectional drilling is ongoing. One such injector is a novel coiled tubing linear injector which further extends coiled tubing capability beyond that known heretofore. When used in combination with a mast capable of handling conventional tubing, none of the functionality of the conventional rig is sacrificed while achieving enhanced capabilities by the addition of coiled tubing. Where it would normally be required to use a very tall mast for making up stands of sectional pipe, a shorter mast can be implemented with coiled tubing. Further, by providing a mast which is accessible on two sides, and having a side-shifting crown assembly with dual block/hooks combinations, then operations with both conventional sectional and coiled tubing is radically simplified and streamlined.
In a preferred embodiment, two rigs are provided. A first rig comprises a collapsible mast on a trailer, a substructure, rotary tubing drive means (table or power swivel), side shifting crown, dual blocks and dual drawworks. An integrated hydraulic system powers the drawworks, side-shifting crown, rotary table and lifts the collapsible mast. A second rig comprises a coiled tubing injector and a reel of coiled tubing on a trailer. Suitable support equipment is provided such as a mud system, mud pump and control house. The two rigs are arranged tail to tail. The mast, when erected, has a first side open to the deck of the trailer of the first rig, forming a catwalk for drill pipe. The opposing side of the mast is open to the second coiled tubing rig. Accordingly, lengths of sectional tubulars can be handled or drawn up the first open side from the first rig; and coiled tubing can be introduced from the second side.
While other injectors of mast-capable installation are anticipated, in the most preferred embodiment, the novel injector meets all the requirements, having a shallow depth and can idle, set aside in the mast, when handling sectional tubulars (tubing or casing). Simply, the preferred injector comprises a linear section of an endless chain conveyor with an opposing linear array of tubing hold-down rollers. As disclosed above, by eliminating the prior art dual and parallel chain drives it is possible to eliminate the known difficulty of synchronizing the two drives and to avoid the bulky machinery of dual chain drives required to hold the dual drives in facing relation. Further, the substitution of non-driving rollers for one side of the tubing injector results in less damage to the coiled tubing. Further, by eliminating the challenge of maintaining dual chain synchronicity, the novel injector is able to take unrestricted advantage of an extended length of a linear driving section, thus providing superior injection and pulling capability and enabling use of conventional diameter tubing.
Accordingly, in one preferred aspect of the invention, deep wells can now be drilled with coiled tubing, even from the surface, due to the implementati
Precision Drilling Corporation
Sheridan & Ross P.C.
Suchfield George
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