Acid placement and coverage in the acid jetting process

Abstract

Many open-hole acid treatments are being conducted by pumping acid through jetting ports placed at the end of coiled tubing or drill pipe. The filter-cake on the bore-hole is broken by the jet; the acid-soluble material is dissolved, creating wormholes in the formation. This combination of two acting factors creates more stimulation beyond the jetting action area. Existing papers have mentioned the advantages of using jetting both for damage removal and as the preliminary stage before further acidizing. Many papers discuss theory and practical implementation of wormholing during acid jobs and the resulting injectivity enhancement, too. However, there is no complete research regarding jetting efficiency with regards to permeability restoration due to filter-cake disruption, and therefore, no data exists for efficient filter-cake removal by acid jetting just prior to wormholing. My project objective is to conduct experiments of acid jetting, defining the parameters that aid to restore injectivity. Based on the parameters obtained from the experiments, I developed a set of recommendations for acid jetting design and optimization.