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Abstract The techniques applied to control down-hole sand production have not changed for very many years. Almost every sand control solution involves the installation of a pipe-based filter that is either gravel packed or left as a "stand alone" screen. Gravel packing has evolved over more than 70 years, but still involves complex fluid and gravel pumping operations. Standalone screens, while being operationally very simple, do not support the formation, leading to a number of well reliability and production issues. Expandable sand screens were developed to overcome the shortcomings of both existing techniques, while also providing some unique benefits. The first commercial application of this technology took place in January 1999. Since then, their use has spread quickly to all parts of the world and in many diverse applications. As of November 2000, over 23,000ft of expandable sand screen had been run in over 25 applications. However, its introduction and acceptance into the U.S. has been slower in coming. It was not until early in 2000 that Chevron decided to complete its West Delta 117 field, well G- 7 S/T1 sidetrack, using expandable sand screen for sand control, thus making it the first such completion in the Gulf of Mexico This paper will provide a brief overview of expandable sand screen, its construction and advantages and will describe some of the issues addressed in this well completion. It will provide details of the installation procedure, the fluids employed and well production results achieved. It will conclude that the use of expandable sand screen as an alternative to conventional sand control methods in the Gulf of Mexico is viable. Background Field and well history. The West Delta 117 Field was discovered in 1962 and has since been developed by Chevron with over 100 wells drilled in the field. The pay sands are stacked deltaic deposits from 4900' to 14,500' and range in age from early Pleistocene to late Miocene. Sand control is installed in most wells in the field to address historical sand control problems. Objectives of sidetrack and re-completion. In May 2000, the OCS-G 9690 G-7 S/T1 well was drilled as an extended reach well to a seismic bright spot in the B-1 Sand at 4865' TVD. One other takepoint in the B-1 Sand had successfully produced gas in a separate fault block with a high rate water pack installed for sand control. The G-7 S/T1 well logged 16' corrected gas on water. Initial appraisal indicated that completing this well with a conventional gravel pack would not generate the best economic solution and that a completion with stand alone screens would not be sufficiently durable to assure a producing life with adequate longevity. Expandable sand screen offered the ability to control sand production without a frac-pack, but also promised to overcome the plugging and erosion problems of stand-alone screens. Further, the elimination of the frac-pack brought the project into economic reality by lowering the initial cost as well as reducing the risk of early water production compromising gas production. |
