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Initial liner top integrity is a primary concern for most operators. If the liner top fails routine or regulatory integrity tests, expensive and time-consuming remedial operations increase direct costs for equipment and services. This remediation delays well completion, which ultimately delays revenue generation. These expenses often exceed the initial cost of the liner equipment. Liner top failure continues to challenge the industry despite improvements in integrally run liner top packers, special cements, and cementing pratices. Even newer generation liner top packers, run either integrally with the liner hanger or as a second trip packer, have multiple sealing surfaces that must function under rigorous conditions to achieve liner top isolation. The expandable liner hanger has been developed and successfully field-tested as an alternative to conventional "cone and slip" liner hangers and liner top isolation packer systems. The expandable liner hanger combines the functions of the liner hanger and the isolation packer into a single component. The expandable liner hanger uses elastomeric "bands" to provide the axial load capacity of a conventional liner hanger and the annular sealing capability of the liner top isolation packer. The expandable liner hanger is expanded hydraulically with the liner running/setting tool assembly. During expansion, the elastomeric bands are compressed into contact with the ID of the supporting/intermediate casing, virtually eliminating the annular space between the liner hanger and the casing. This paper discusses expandable liner hanger design criteria and testing undertaken to qualify the expandable liner hanger as a reliable liner top isolation system. Initial field installations and the lessons learned are also discussed. Introduction The importance of the liner-casing overlap is illustrated by the efforts and expense taken by operators to ensure hydraulic integrity of the overlap. Typical methods of achieving pressure integrity include the following:Cement "squeezes," including a liner top packer as a component of the initial liner hanger settingOne or more "second-trip" liner top isolation packers installed to control gas migration at the liner top The typical liner top is complex in its design (Fig. 1) and can develop leaks due to a myriad of causes1. A recent informal survey of several GOM operators revealed that 30 to 50% of pressure seals in overlaps fail. One operator made a concerted effort to improve liner running and cementing procedures. Data gathered over an 18-month period was used to shed light on possible causes of overlap failure by gathering information on liner/casing sizes, types of equipment, overlap length, mud data, annular cross section, equipment, and service suppliers. The study concluded the chances of having a liner overlap seal failure did not depend on any single factor and the chances for an incident were nearly the same regardless of the factors associated with any given well2.

A 3,142-ft length of solid expandable openhole liner was installed successfully in a BP-operated well in November 2001. This established an industry record length and demonstrated two improvements:654 ft of liner were simultaneously expanded and pumped to the bottom of the well without the need to stop to make connections;a sliding sleeve valve permitted cement placement postexpansion prior to drill-out. These improvements delivered significant time savings and offer reduced risk plus greater flexibility in the use of solid expandable liners. This work was conducted as a technology field trial at an onshore location before trying it in the higher cost offshore environment. Key steps were taken to reduce the risks of this trial, including provisions to completely recover the expandable equipment from the well in the event of a problem. Also, risks unique to the relatively shallow depth of this installation were addressed and minimized. Introduction Expandable tubulars introduce promising solutions to some of the challenges encountered in engineering and economics of wells. A growing body of literature describes expandable tubulars mechanics, applications and field case histories.1-6 The first commercial installation of an expandable openhole liner was accomplished in November 1999. The work presented here was the 16th of 18 expandable liner installations undertaken by industry in year 2001. This paper reports fresh progress with upgrades to the knowledge and applicability of solid expandable tubulars. The concept of solid tubular expansion in wells is fundamentally proven, but as with many new technologies the commercial uptake can be slowed by end-users' concerns about risk, reliability, versatility, etc. BP's offshore operations teams have been instrumental in voicing their expectations and requirements for expandable tubulars. This in turn has enabled our drilling technology group to prioritize the goals of an onshore expandables field trials program. We believe that field trials such as the one described here are an effective way to identify areas for improvement, demonstrate progress and ultimately gain confidence that leads to faster and more efficient utilization of the new technology. Project Goals Three technical advances and a fourth technical objective were sought in this field trial: Expand more than 3,000 ft of liner. Certain deepwater drilling environments require dependable 3,000+ ft capability in order for expandable liners to be of practical use. End-users tend to view solid expandable tubulars as an unwarranted risk if success in their well entails doing something not previously accomplished. The greatest lengths run prior to this test were in the range of 2,462 ft, 2,342 ft and 2,186 ft; hence the goal was to demonstrate deployment of more than 3,000 ft length, with deepwater drilling staff present to gain first-hand experience. Expand via "scoping" technique. The term scoping describes extruding the liner off the face of the expansion cone while literally pumping the expanding liner to the bottom of the wellbore.

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.