The results from the successful Minas Surfactant Field Trial 2 (SFT2) and the polymer field trial (PFT) will be presented. The sandstone reservoir had a very high water cut, >99% and required multiple innovations for successful pilot deployment and interpretation. For interpretation, we used quantitative tracer interpretation to estimate sweep and displacement efficiency and confirm the performance of both SFT2 and PFT. The pilot patterns in both SFT2 and PFT consisted of a central producer surrounded by six chemical injectors and further confined by six hydraulic control wells that injected water alone. In order to make quantitative comparisons, both the surfactant-polymer and polymer pilots were run at the same mobility ratios to understand if incremental recovery was a function of improved volumetric sweep or increased displacement sweep efficiency. The results of the two pilots show that at the same well spacing and mobility ratio, incremental sweep is very similar and significantly higher than pre-chemical waterfloods. An important finding of the tracer tests is that water injectors should not be used to confine chemical injectors as the water tends to bypass the higher viscosity polymer chase and potentially disrupts the oil-bank. The results from the pilots indicate that for a mature, waterflooded reservoir, surfactant-polymer flooding was preferable as it lowered the final remaining oil saturation and increased oil recovery. Polymer flooding mainly accelerated oil recovery by recovering additional oil from unswept zones and had minimal impact in a mature reservoir. Interwell tracer technology combined with moment analyses were used to make quantitative comparisons of both processes and allowed for several technical insights. This is the first time in literature that a quantitative comparison of surfactant-polymer flooding and polymer flooding alone has been presented. In addition, we also present lab results to illustrate how field results may be used to further optimize chemical and reduce chemical usage in a field surfactant polymer project.
Bio: Varadarajan Dwarakanath (DW) received his B.Tech in mining engineering at the Institute of Technology, Banaras Hindu University in 1990. He then joined the graduate petroleum engineering program in UT Austin and received M.S. and Ph.D. in 1992 and 1997. He started his career as a Senior Geosystems Scientist at INTERA in 1997. In INTERA, he built and led the aquifer remediation research laboratory. He was responsible for the design and deployment of twenty-five partitioning tracer tests and nine surfactant, surfactant polymer and surfactant-foam projects. He spent two years in Yucca Mountain as Lead Analyst for the Yucca Mountain Nuclear Waste Management project where he validated the Total System Performance Assessment model. He joined Chevron in 2005 as a Simulation Engineer and then took on the role as Technical Lead for Chemical EOR. He designed and helped deploy the successful Minas surfactant pilot, the Captain polymer pilot, and Captain polymer scale-up. His current role is the Team Lead for Chemical Recovery Mechanisms where he develops Improved Oil Recovery Technologies for Unconventional and Heavy Oil resources.
He has co-authored twenty peer-reviewed publications, more than thirty-five conference publications, 188 patent applications, over thirty U.S. patent grants, and ninety-five international patent grants. His other interests involve mentoring young engineers and developing research relationships with Universities and other vendors with an eye toward technology deployment. Dwarakanath was recognized as a distinguished alumnus of the Petroleum and Geosystems Engineering Department of UT Austin in 2012. He was awarded the SPE IOR Pioneer Award and SPE/AIME Robert Earl McConnell Award in 2024. He is also a Distinguished SPE Member.