Wettability Alteration for Water-Block Prevention in High-Temperature Gas Wells

Abstract

Abstract This paper presents the development of a chemical system for water-block prevention in gas/condensate wells. The chemical system alters the formation wettability to intermediate gas wet conditions thereby decreasing the capillary forces and enhancing the clean up of trapped water at low drawdown pressures. Five different chemicals (A1-A5) are evaluated in this study for their ability to prevent water block formation at high temperature. Adsorption/desorption characteristics of these chemicals and temperature stability are also investigated for long-term prevention of water blocks. Contact angle and air-brine imbibition tests are conducted to determine wettability alteration before and after treatment with the chemicals. The results show that chemical A5 gives the best wettability alteration at high temperature with minimum formation damage. The improvement in water block removal after treatment with A5 is tested by injecting gas into brine-saturated cores at different pressure gradients and measuring volume of displaced brine. Higher volumes of brine clean up and lower flow initiation pressure gradient are observed after the treatment.