INSERTION OF LINERS INTO HOST
TUBULARS BY FLUID INJECTION
CROSS-REFERENCE TO RELATED
This application is based on and claims priority from U.S. provisional patent application 60/094,585 filed Jul. 29, 1998, in the name of Jack C. Taylor.
This application is related to Ser. No. 08/532,561 filed Jun. 4,1990, now U.S. Pat. No. 5,072,622; and the following provisional applications, all filed in the name of Jack C. Taylor: Ser. No. 60/093,665 filed Jul. 22, 1998 and its corresponding PCT Int'l. Appln. No. PCT/US99/16612 filed Jul. 22,1999; Ser. No. 60/094,326 filed Jul. 28, 1998 and its corresponding PCT Int'l. Appln. No. PCT/US99/16968 filed Jul. 28, 1999; and Ser. No. 60/138,814 filed Jun. 14, 1999.
Some, but not all, of the aspects of the invention described herein have been filed under the USPTO Document Disclosure program by Jack C. Taylor under reference number 424712 (Sep. 18, 1997).
The foregoing disclosures are incorporated by reference herein.
BACKGROUND OF THE INVENTION
Pipe and other tubulars have been lined with tubular polymeric liners, e.g., polyethylene, nylon 11, etc., for many years. These systems have been used principally in offshore and onshore pipelines, and in downhole production tubulars. Generally, the liner resides in close-tolerance with the host pipe along its length, forming a stable composite system. See FIG. 1, which is a cutaway end view of a lined tubular.
Several installation techniques are known to the art. However, they have all retied upon one of two methods to insert the liner into the host tubular; either pulling or pushing from one end or the other. Typically, to pull liners in, a cable is used, or if in the vertical direction, weights in conjunction with gravity have been employed to the same effect. In pushing methods, usually a four-step cycle is used upon the liner, consisting of the steps of clamp-push-releasereposition.
Under the current art, the maximum length of an individual installation segment has been limited by the mechanical properties of the liner in concert with the friction drag accumulated during the insertion process.
For example, for polyethylene liners installed in diameterreduced fashion, e.g., the known TitelinerTM and SwagelinerTM systems and the like, installation lengths tend to average 2500 feet, and the maximum permissible length is approximately 5000 feet. Tensile loads, borne totally by the liner, continually climb throughout the insertion process, in proportion to distance pulled, with all the force being directed through the leading end of the liner. As a result, when longer lengths are attempted, the liner simply pulls apart.
In pushing methods, the practical lengths tend to be even shorter. The relatively flexible liners quickly assume an 'S-curve' within the host due to the pushing. The resultant friction against the host wall is thus amplified, and the process simply stalls.
Generally, in either case, bends in the host pipe substantially diminish achievable insertion length. Drag between the liner and the host pipe increases dramatically due to bends that the liner passes. The increase in lateral pressure due to a bend increases the total friction between the two elements. Lining of reeled pipe is virtually impossible, since all segments that are to be lined must be relatively straight for best effect.
SUMMARY OF THE INVENTION
The invention relates to a method of injecting liners into host tubulars. Fluid is pumped into the host pipe concurrent with introduction of the liner. The momentum and drag imparted by the fluid to the liner induces axial motion of the liner for insertion into the tubular. Also, the pressure of the fluid in the host maintains the liner in a reduced crosssection throughout the insertion process, minimizing drag.
10 The invention extends the maximum installation length. It facilitates the ability to insert a liner over long distances, into those lines where sectioning into short distances is impractical, or impossible; e.g., water crossings and restricted rights-of-way. It can also be used to install liner
15 into reeled pipe as well as straight pipe. These benefits translate directly to lower project costs. Fewer insertion operations are necessary for any in-situ rehabilitation project where the line is multiply sectioned, resulting in reduced time, hardware and overall cost. The invention also permits
20 lining of new host tubulars at a plant-site for improved logistics and quality control. A final benefit of the method is that less longitudinal stress is imparted on the liner, minimizing failure potential and thus enabling longer service life.
25 The method is equally suitable to both pipeline, i.e., essentially horizontal, and downhole, i.e., essentially vertical, applications.
Other features and advantages of the invention will become apparent from the following detailed description, in
30 conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of a conventional lined tubular.
FIG. 2 is a schematic diagram of an apparatus for carrying out a method according to an embodiment of the invention.
FIG. 3a is an isometric view of a deforming apparatus comprising three sets of rollers. 40 FIGS. 3fc-3e are cross-sectional views of a liner showing successive stages in the process of deforming the liner.
FIGS. 4a-4g are cross-sectional views illustrating various configurations of a liner after deformation.
FIG. 5 is an enlarged cross-sectional view of a packing gland/lubricator unit.
FIGS. 6a-6c are cross-sectional views showing various stages in the process of capping a host tubular and expanding the liner to its original shape.
50 DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
The liner to be installed is approximately the same length as, or up to 5% longer than, the host tubular. The initial liner 55 configuration may vary. It may be extruded in one piece on a reel, it may consist of multiple reels joined by fusion techniques known to the art, or, it may consist of multiple joints similarly joined and either reeled or extensively laid out.
60 The liner enters the installation equipment without substantial pre-existing axial longitudinal tensile stress (unlike in known pulling methods). A minimal starting load minimizes the axial force that the flowing fluid must impart on the liner for insertion.
65 In one embodiment, shown in FIG. 2, the liner 10 is on a reel 12 adjacent to the installation point (the packing gland/ lubricator unit 30). The reel is powered or free-wheeling. In