Aluminum drillpipe was used to drill the first five directional wells from a North Sea platform. A comparison with steel drillpipe showed that the operational problems of using the aluminum drillpipe outweighed the benefits in the directional wells drilled. Therefore, steel drillpipe was specified for subsequent, similar platform wells. IntroductionIn 1971, Mobil North Sea Ltd. became the operator of Block 9113 in the U.K. sector of the North Sea. The block is located 215 miles northeast of Aberdeen. The Beryl field was discovered in Block 9/13 in 1972 in water depths from 350 to 400 ft. The Beryl A production platform, a concrete gravity structure equipped with two drilling rigs, was installed in 1975, and oil production began in 1976. The Beryl B production platform, a steel-jacket structure equipped with a single drilling rig, was installed over a drilling template in 1983, and oil production began in 1984. Six wells had been predrilled through the 21-s10t Beryl B drilling template, so the first job of the platform drilling rig was to tie back and complete these wells.Aluminum drillpipe and a top drive were incorporated into the Beryl B drilling rig as a result of recommendations from a jointindustry extended-reach-drilling (ERD) projectl,2 and the local drilling manager's experience with using aluminum drillpipe in remote land operations. This paper presents information on aluminum drillpipe selection, required rig modifications, establishing operating limits, operational benefits and problems, and ways to extend service life. A comparison with steel drillpipe provides a frame of reference, and the results from a drillstring simulator quantify the surface torque reduction achieved in an example Beryl B well.Aluminum drillpipe was used during a series of casing-repair workovers on the predrilled wells and to drill five directional wells from mid-May 1984 to mid-Nov. 1986 (see Fig. 1). The pipe was then taken out of service for a full inspection and was found to require extensive tool-joint rebuilding that could not be done in the U.K. Pending the decision to drill any long-reach wells that required the special attributes of aluminum drillpipe, we stored the pipe and used a string of steel drillpipe for continuing operations on Beryl B. (A steel drillstring was available at no additional cost because only one rig on the Beryl A platform was being used for drilling operations.) Selection and Preparation of Aluminum DrlllpipeSelection. The 21,000 ft of 5-in. aluminum drillpipe with extralong 5'h-in. full-hole (FH) tooljoints purchased for use on the Beryl B rig was chosen because it was comparable to the 5-in., Grade G steel drillpipe used on the Beryl A platform rigs.As the buoyed-weight and available-pull data in Table 1 show, the pull capacity of aluminum drillpipe exceeds that of Grade E drillpipe and compares very favorably with that of Grade G drillpipe. Note that the buoyed weights in lO-lbm/gal fluid and 90% of the new pipe tensile ratings were used to calculate the available pull values at the vertical d...

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