Pilot Tests of Enhanced Oil Recovery by Integrating Conformance Control Treatment and Surfactant Flooding for Low Permeability Reservoirs

Abstract

Abstract For fractured low permeability reservoirs, there are challenges to enhance oil recovery after water flooding with high water cut contents. Because of unsatisfied surfactant polymer flooding, we explored the integrated EOR techniques of conformance control treatment and surfactant flooding. This paper analyzes the results of pilot tests with four injectors and 16 producers and concludes the effectiveness of integrated EOR techniques. Based on lab results of conformance control core flooding tests and surfactant based chemical EOR reservoir core flooding experiments, we did pilot simulation studies to develop pilot design parameters. Then through history match and detailed compositional simulation, we made EOR integrated technology design and compared several injection scenarios by predicting the potential performance. Finally, an integrated EOR technique with two conformance control treatments and surfactant flooding was selected and executed for three injectors in the interested pilot block. For the fourth injector, only surfactant flooding was used to compare. Lab results of conformance control core flooding tests showed the efficiency of plugging and a good fluid diversion performance of conformance polymer agents. Surfactant based chemical EOR reservoir core flooding experiments resulted from 70% to 98% residual crude oil recovery. The experimental data obtained was implemented in a numerical simulator model to find the potential incremental recovery associated with conformance control treatments and chemical flooding. A refined sector model used to further evaluate the effect of them. Positive simulation results boost pilot tests. Five fluid injection slugs including the cleaning slug, pre-flooding slug, near wellbore plugging slug, in deep conformance control slug, and surfactant flooding slug were run for three injectors in the range of eight to ten months of treatment. In the interested pilot block, the monthly decreasing rate of oil production dropped from 3.58% before treatment to −1.04% during treatment. Comparing the oil production data from the fourth injector with those from other three injectors, we observed monthly oil production rate increases from 4.25% to 7%. These results highlighted the importance of conducting a conformance control treatment before surfactant flooding, especially in fractured low permeability reservoirs. The results of pilot tests in this work shed light on designing integrated EOR techniques. These positive results of controlled high water cut and improving oil production are promising enough to go towards a larger field project.