Investigation of the film-forming flooding mechanism of molecular deposition in tight oil reservoirs

Abstract

Most of the oil fields in China have entered the stage of high-water-content development, which has become the primary means to improve the recovery rate of high-water-content oil fields by changing the injection agent. MDFFA membrane oil drive technology is a new type of tertiary oil recovery technology that uses an aqueous solution as the transfer medium; however, it is rarely applied in the field of tight oil reservoirs in China. In this study, molecular film-wall microgravity and water-wall microgravity were compared for tight reservoirs in the Shengli oilfield. It was concluded that the MDFFA dominates in competitive adsorption, breaks through and removes the hydrated layer, and finally adsorbs firmly on the pore wall to form a nanoscale ultrathin film. The application conditions of the MDFFA were also explored, and its wetting angle was tested. Further, the variation law of MDFFA adsorption was studied, and the mechanism of MDFFA drag reduction was explained in terms of reducing the boundary layer effect and water injection friction resistance. The natural cores procured from the Shengli tight oil field were analyzed for MDFFA membrane drive cores, and a reasonable injection concentration was selected. Through a series of mechanistic and experimental studies, we provided theoretical and technical references for the development of increased tight oil production.