A method called "scoping" for installing solid expandable tubular (SET) drilling liners across pressure-depleted zones has been developed and demonstrated. High overbalance pressures associated with pressure-depleted zones are known to interfere with conventional SET expansion. Scoping is a dynamic expansion method that keeps the expandable tubing in continuous motion thus reducing risk of stuck pipe and SET failures related to differential sticking. This paper describes how scoping is performed and how it worked in a test well. Introduction The concept of solid tubular expansion in wells is fundamentally proven. A growing body of literature describes expandable tubulars mechanics, applications and field case histories.1–7 The most common expansion method involves deployment of a solid expandable tubular (SET) liner on an expansion cone assembly connected to a work string. The SET is run to within 5 to 10 feet of the well bottom then expanded hydraulically from the bottom upward. Initially the expansion cone remains stationary as the liner is hydraulically pushed downward while it expands. The expanded liner stops advancing when it reaches bottom, then the cone and work string are hydraulically pushed upward as expansion continues. Both the pipe OD and ID are enlarged in the expansion process. If the ends of the expandable tube are "fixed" and unable to move, then expansion occurs entirely through thinning of the pipe walls. Wall thinning reduces tubular strength and can be particularly detrimental to the "flush type" threaded connections of the SET. Solid expandable tubulars in contact with a pressure-depleted zone can be susceptible, like other tubulars, to "differential sticking" over a portion of the length thus placing that pipe length in a "fixed - fixed" condition (Fig. 1). If a SET system becomes differentially stuck above the expansion cone (i.e., before expansion), the sticking force may prevent the pipe from shortening during expansion. Thus, the pipe walls may thin excessively. If this occurs, the risks to damage or failure at the connection are increased. Prevention of wall thinning at the connection of a SET system is one of the keys to successful installation. To minimize wall thinning, one end of the expandable tube (in this case the upper end) should be free to move so that diametric expansion occurs primarily through shortening of the pipe. Scoping was invented as a method to expand SET systems in the presence of pressure-depleted zones. The purpose is two-fold:to expand the pipe before it comes into contact with pressure-depleted zones, so that expansion occurs primarily through shortening of the pipe with a minimum of wall thinning;to keep the pipe, once expanded, continuously advancing toward bottom while in contact with such zones to further reduce the risks of differential sticking. Scoping differs from standard expansion in that the expansion cone assembly is initially positioned far off-bottom in the open hole between the previous casing shoe and the depleted zone. The liner is then extruded off of the expansion cone face, literally pumping the expanded liner to bottom. The continuous movement of the expanding casing reduces risks of differential sticking. A purpose-built scoping shoe permits cementing after pipe expansion on the same trip in the well. System Overview Expandable Liner Assembly The expandable liner system design for scoping is the same as for conventional bottom-up expansion, except a scoping shoe (a sliding valve that allows circulation around the liner after expansion is initiated) was used. Differences between conventional and scoping expansion are depicted in Fig. 2 and Fig. 3.
TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractIn November 2002 BP America installed four expandable tubular casing patches, totaling 5,000 feet in length, in three Texas Panhandle gas wells that had been shut-in due to corrosion leaks. The casing repairs were successful and the wells were restored to production. The jobs were completed consecutively in rapid sequence. This contributed to improved workover economics and quick implementation of lessons learned. This paper details project objectives, job design and implementation, plus problems encountered, unique solutions and best practices established as the result of this work. Successful application of this new technology has given the producing asset a cost-effective alternative to the standard practice of squeeze cementing to fix casing leaks.
Congenital lower-limb deficiencies, which have not been converted by amputation, usually present with shortening as well as deformity and joint defects. It is normal practice to equalize the length by the use of a bootee, prepared from a cast, which is attached to a platform mounted above appropriate prosthetic components. In writing the prescription for the prosthesis (Fig. I), con
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