Development of High-Performance Surfactants for Difficult Oils

Abstract

Abstract We present results for high molecular weight internal olefin sulfonate (IOS) surfactants that show excellent performance when tested using several crude oils with characteristics such as high wax content and viscosity that have made it very difficult to achieve high oil recovery with most surfactants used in the past. High carbon number internal olefin sulfonates when used with appropriate co-surfactants, co-solvents and alkali show the type of phase behavior and ultra-low interfacial tension needed for almost 100% oil recovery in cores. This work shows how the performance of both surfactant-polymer and alkaline-surfactant-polymer flooding can be dramatically improved at the same or lower cost than with conventional surfactants and applied over a wider range of reservoir conditions. High carbon number internal olefin sulfonate surfactants gave good performance at low concentrations and were found to be compatible with both polymers and alkali such as sodium carbonate when used with appropriate co-solvents. The extremely efficient and effective approach for finding high performance surfactants that we previously presented for light crude oils has now been successfully extended to heavier crude oils. The identification of high-performance surfactants suitable for high-temperature and/or paraffinic oil applications opens up the potential to recover a vast amount of additional oil outside the range of conditions considered practical in the past.