Experimental Study on the EOR Performance of Imbibition and Huff and Puff in Fractured Tight Oil Reservoirs

Abstract Injection of imbibition fluids or CO2 during hydraulic fracturing is an effective stimulation method for tight oil reservoirs. Selecting appropriate agents significant to optimize the integrated scheme and production in In this study, a series lab experiments, including spontaneous imbibition, dynamic huff puff, were carried out using real cores, water absorption apparatus, core flooding equipment. The EOR performances fractured cores compared. mass transfer reservoirs its influence on sweeping volume mechanisms discussed. results show that (1) rate slow, recovery factor by cracked relatively high, up 13.42%. (2) final injection was significantly higher than injecting liquids. Because excellent miscibility effect CO2, mainly occurred primary displacement stage. Comparatively, played role after well shut-in, which can increase 7.35%-11.64%. (3) puff mode performance greater due more sensitive compressibility rate. Generally, high be obtained if depletion conducted first, operation followed. (4) Comprehensively understanding characteristics guide parameter design, such as order fluid slugs, optimal soak time, fracture spacing.