Surfactant Blends for Steam Foam Applications up to 570°F (~300°C)

Abstract

Abstract Steam injection with foam presence (steam foam) was successfully implemented in the 1970's and 1980's. The purpose of having steam foam as a mobility control agent was to improve sweep efficiency by minimizing detrimental effects associated with steam injection processes such as viscous fingering, gravity override, loss to thief zones, etc. Previous work, published in SPE-190473-MS and SPE-193634-MS, discussed results on thermal stability and foamability of Alkyl Ether Carboxylate Acid (ECA) at temperatures up to 200°C-250°C in the presence/absence of bitumen. This paper, as a continuation of the work mentioned above, presents the blending of ECA with surfactant A (a chemically different surfactant) at 50/50 ratio and different injection foam qualities (30% to 90%) for further improvement of steam foam performance at 300°C without bitumen. For safety reasons, thermal stability test at 300°C using Parr reactors was not conducted because of identical rated temperature on the instrument. Surfactant foamability was evaluated through bulk foam test in a high temperature high pressure (HTHP) visual cell based on the recorded life-time of foam column. Two Internal Olefin Sulfonates (IOS) from Shell were also tested and used as benchmark for comparison with ECA itself and the blend at 250°C and 300°C. Through sand-pack tests conducted at 300°C, foamability in porous media of ECA – surfactant A blend at different injection foam qualities was compared against ECA itself for observation of improvement with regards to increasing steam apparent viscosity in the absence of bitumen. Results showed that the presence of surfactant A improved foamability by 50% at 50/50 blend in bulk foam test. Sand-pack test results confirmed significant increase of steam appearance viscosity with the addition of surfactant A. Varying injection foam qualities resulted in 30% and 50% being the best foam qualities in terms of increasing steam apparent viscosity as compared to 70% and 90% foam qualities. The findings of this study once again confirm the effectiveness of steam foam as a mobility control agent for steam injection processes. The addition of surfactant A to ECA improves foamability at 300°C which broadens the application of steam foam to reservoirs with similar operating temperature. Sensitivity study on injection foam qualities provides insights on process design with respect to desired foam strength and gas availability.