Sand Clean Out and Acidization of Predrilled Liner Horizontal Hole Sections: A Field Experience

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThis paper describes sand cleanout / acidizing operations of four horizontal pre-drilled liner completions in the UU field, offshore Nigeria. These wells were drilled and completed concurrently with similar completions in 1996. Production from the wells declined after four years. The wells were studied using production history curve analysis and nodal analysis techniques. Analysis indicated that the most probable cause of the decline in productivity was plugging of the completion with solids/deposits. Detailed analysis and flow testing were carried out on the available core samples from an analogue well to determine the mineralogy of the possible plugging solids and the most effective treatment recipe to be used to remove the plugging materials. Based on the results of the core analysis, sand cleanout /acid stimulation operations were executed on the subject wells, using coil tubing and specialized coil tubing tools.The operation resulted in a 300% increase in productivity, and was both a technical and economic success.