Mechanism of Using Dilute Microemulsion System (DMS) on Enhancing Hydrocarbon Production from Low Permeability Reservoirs

Abstract

Dilute microemulsion system (DMS) can reduce the adsorption of surfactants on the rock surface, and it has been widely used as fracturing fluid additive for low permeability reservoirs in recent years. In some cases, it can reduce the water block caused by the invaded fracturing fluid and enhance the hydrocarbon production rate; while in some cases, it cannot. Although a few theories and models have been proposed to explain this discrepancy, it is still unclear (1) when DMS can enhance the hydrocarbon production, and (2) the impact of using DMS on hydraulic fracturing, flowback, and production. In this study, the imbibition test, contact angle test, and core flooding experiment were conducted to explore the answers to the above questions. Results from imbibition cell tests and contact angle measurements indicate our DMS can alter rock wettability from oil-wet to water-wet within half a day, but it cannot alter water-wet originally rocks. In core flooding experiments, the invasion step shows that the relative permeability to water is reduced after using DMS, suggesting DMS can reduce the forced water invasion during hydraulic fracturing; the flowback step shows that 0.1wt% DMS can reduce the water block and enhance the production rate by 12% comparing to the brine.