The Use of Coiled Tubing During Matrix Acidizing of Carbonate Reservoirs Completed in Horizontal, Deviated, and Vertical Wells

Abstract

Summary A laboratory and field study directed at improved well performance of horizontal wells is discussed. During the study, several wells were matrix acidized by use of bullhead and coiled tubing (CT) placement techniques in carbonate reservoirs. The study indicates that acid placed with CT diverted with foam, or a temporarily crosslinked gelled acid (TCGA) system, provides excellent zone coverage and damage removal. Conventional bullhead techniques do not result in effective damage removal. The study emphasizes the evaluation of the treatment results and the development of improved acidizing techniques. Computer simulations of matrix acidizing indicate that proper placement techniques are essential. This observation is supported by field data in wells completed in carbonate reservoirs. The keys to successful damage removal are the placement of acid through CT and proper diversion. Production-logging and well-performance data support this claim. The proposed treatment is applicable in both horizontal and vertical wells completed in carbonate reservoirs.