Publications

The biggest challenge for success during matrix acidizing treatments on high temperature carbonate formations is the creation of an effective network of wormholes as the acid dissolves the rock. Typical matrix treatments often require low injection rates, and therefore pure hydrochloric acid cannot be used because rapid acid spending severely limits the acid penetration distance. This causes face dissolution and fails to create a wormhole network long enough to effectively bypass the damaged zone around the wellbore.The Sungai Kenawang onshore gas-condensate field, located at the southwest part of the Jambi Merang block in the South Sumatera Province, is a carbonate buildup, which is part of an isolated bank containing a group of buildups. The Baturaja formation, located at depths around 7,000 ft, is a thick gas condensate reservoir with permeabilities in the range of 10 to 350 mD, bottomhole temperatures range of 280 to 350 °F and the presence of H2S. The standard method used to stimulate these carbonates was pumping 15% gelled hydrochloric acid through coiled tubing. Production logs and pressure build-up analysis have shown post-stimulation positive skin values and that the production was mainly coming from the upper zones, with minimal contribution from the lower zones.This paper describes the application of a high temperature, highly retarded emulsified acid system that slows the reaction times by a factor of 10 to 40 compared to conventional HCl systems. The emulsified acid system combined with a selfdiverting viscoelastic surfactant based acid was able to achieve complete stimulation of a 197 ft long perforated interval without the need of coiled tubing. A Pressure build-up showed a poststimulation skin value of - 3.28 and the production log analysis demonstrated complete and uniform zonal coverage with the upper zones contributing with 53% of the total well production and the lower zone with 47%.