Wells – Guide for device or conduit – On sucker or pump rod
Reexamination Certificate
1998-11-04
2001-07-17
Bagnell, David (Department: 3673)
Wells
Guide for device or conduit
On sucker or pump rod
C166S241400, C166S241600
Reexamination Certificate
active
06260617
ABSTRACT:
FIELD OF THE INVENTION
The instant invention relates to a method and apparatus of injecting tubing down a pipe or open hole. In particular, the instant invention relates to a method and apparatus of injecting coiled tubing down a pipe in deep water to provide servicing of the pipe to remove paraffinic blockages, hydrates, scale, or solid debris from the pipe. More particularly, the instant invention relates to a method and apparatus of injecting tubing into a pipe, wherein a substantial portion of the pipe is horizontal.
BACKGROUND OF THE INVENTION
In the development and production of subterranean hydrocarbon deposits and other energy sources there are many occasions when it is necessary to insert an elongated tube from the surface deep into a pipe or open hole. Such pipes or holes may be vertical, horizontal, curved or combinations thereof and may be part of, for example, a well, pipe line, production line, or drill pipe. The inserted tube has an outer diameter that is smaller than the inner diameter of the pipe or open hole. The insertion of the tube may be for such purposes as, for example, removing blockages or general servicing.
Often during repair or servicing of a pipe a rig capable of handling long lengths of straight screw-type pipes is not available. In many cases the strength of larger diameter straight screwed tubing is not needed, so the cost of running this type of tube is not justifiable. In these cases it is often advantageous to use a long, continuous injected tubing called coiled tubing. Many apparatus have been developed to insert or inject a continuous length of relatively thin walled steel tubing into a pipe or open hole from a large reel or spool on the surface.
Large forces are often necessary to insert and withdraw thousands of feet or more of steel tubing into a pipe or open hole which may be filled with hydrocarbons or other materials. Most apparatuses developed heretofore have focused on the injector head located where the smaller tubing is injected into the larger tubing. The injector head grips the tubing along its length and, in conjunction with a motor, guides and forces the tubing into the pipe via, for example, a dual, opposed conveyor belt on the surface of the well. Typical injector heads are described in, for example, U.S. Pat. No. 3,827,487; 5,309,990; 4,585,061; 5,566,764; and 5,188,174 which are incorporated herein by reference.
Unfortunately, the apparatuses of these patents are problematic in many respects. One such problem is that the tubing may be bent or kinked, i.e., the tubing becomes helical, down the well due to the large forces pushing against it and the weight of the tubing itself. This is especially problematic when the pipe is deviated from vertical. As the pipe becomes more horizontal, the weight of the coiled tubing itself no longer acts as a force pulling the tubing along, and instead acts against the wall of the pipe, creating friction. In addition, the weight of the tube no longer acts to straighten the coiled tubing, and the coil encourages coiling in the pipe. Such a coil, coupled with friction, results in increased force between the coiled tube and the inner diameter of the pipe, and this effectively binds the tubing. As a result of this and other problems, such prior art devices cannot effectively insert more than about 3,000 to about 5,000 feet (900 to 1500 meters) of tubing in substantially horizontal pipe.
Another typical problem with prior art devices is that the injector equipment associated with such devices is often relatively heavy, difficult to move, and complex due to a large chain assembly machinery which serves as a conveyor belt to force the tubing into the pipe.
Other methods have been employed to increase the length to which tubing can be injected. U.S. Pat. No. 5,704,393 describes an apparatus that can be set in the well at the end of the coiled tubing string at a determinable location. The apparatus is a valve apparatus, a packer apparatus, and a connector. Seals are provided which allows the coiled tubing, but not fluid, to move in a centrally located bore through the packer apparatus. The apparatus is immobile against the outer pipeline, and has the ability restrict or prevent fluid flow. Once the packer is set, the annular pressure , i.e., the pressure differential between the pipeline and the interior of the coiled tubing, is increased by injecting fluid into the annular volume. This increased pressure stiffens and straightens the coiled tubing, allowing for increased distance of injection of coiled tubing into the pipeline.
One method of reducing friction in injected tubing is the tubing friction reducer described in U.S. Pat. No. 5,692,563. This patent describes a friction reducer that contains multiple bearings set in legs that extend outward from a body. The friction reducers described by the patent did not have the mechanical integrity needed to support the weight of larger diameter tubing. Applicant also found that the design of the friction reducers described therein could not be used in field conditions where obstructions in the pipeline are common.
It is apparent that what is needed in the art is a method and apparatus which allows one to readily insert and withdraw tubing from a pipe for long distances, i.e., greater than about 6,000 feet (1830 meters), without bending or kinking the tubing. It would be beneficial if such a method and apparatus could be employed to insert and withdraw tubing from a substantially horizontal pipe of extended length of greater than 6,000 feet (1830 meters), and that the tubing can extend past turns. Moreover, it would be of great benefit if such an apparatus was portable, easily handled, and could be adapted to handle tubing of differing diameters.
SUMMARY OF THE INVENTION
A new method and apparatus have been developed which inserts and withdraws tubing from pipes or open holes. Beneficially, the new method and apparatus may be employed to insert and withdraw tubing to lengths of over 6000 feet (1830 meters), preferably greater than 26,000 feet (9900 meters), and more preferably greater than 60,000 feet (18,300 meters). Advantageously, the apparatus is portable, easily handled, and adaptable to handle tubing of differing diameters.
The instant invention comprises a skate apparatus for attachment onto the outer diameter of injected tubing. The skate apparatus has a body diameter greater than the diameter of the injected tubing, and has a cylindrical port capable of fitting around a portion of the injected tubing. The body is openable lengthwise by a width sufficient to insert the injected tubing. This allows the skate apparatus to securely fit around the outer diameter of the injected tubing. There is a means of fastening the skate apparatus to the outer diameter of the injected tube. Finally, there is a set of three to six, preferably three to four, rigid arms extending in a plane in a direction toward the interior surface of the pipe, wherein each of said arms contains one or more wheels on the distal end of the arms. By in a plane it is meant that there is a cross-section of the skate that will include at least a portion of the three to four arms that radiate out from the body. There may be more than one set of three to four arms on a body, provided the sets are displaced axially along the body from one another.
The wheels are capable of movable communication with the inner surface of said pipe. The radius from the center of the injected tubing to the outermost edge of the wheels or rollers is not smaller than 0.5 times the radius of the pipe. This skate apparatus maintains a portion of the tubing in the center of the pipe such that the movement-restricting force for at least a portion of the injected tubing is rolling friction rather than a combination of sliding friction and the force needed to overcome the shear viscosity of the fluid within the pipe.
REFERENCES:
patent: 712486 (1902-11-01), Black
patent: 712487 (1902-11-01), Black
patent: 712488 (1902-11-01), Black
patent: 712901 (1902-11-01), Black
patent: 879822 (1908-02-01), Karns
patent: 12817
Baugh Benton F.
Crawford James R.
Bagnell David
Howrey Simon Arnold & White , LLP
Singh Sunil
Superior Energy Services, L.L.C.
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