Study on the Influencing Factors of Pre-CO2 Blowback After Pressure

This paper studies the main control factor analysis of shale oil fracturing fluid backflow, and calculates and sorts the weight of each influence factor under 285 samples in west 233 and Zhuang 183 blocks by grey correlation method, the main control factors of shale oil fracturing fluid reflow are segment number, sand ratio and volume of reflow, and the correlation between influencing factors and reflow rate is established based on fuzzy set theory. Taking the construction parameters of Huxx well as an example, a pre-co2 fracturing model of shale oil is established, based on the effects of different CO2 injection rate, pressure difference and muffle well time on slippage water reflow rate, CO2 reflow rate and cumulative oil production, the optimal injection rate of CO2: the injection rate of subsequent slip water (including sand-carrying fluid, displacement fluid, etc.) should be more than 20%, the optimal shut-in time is 15 days, and the optimal bottom hole flowing pressure is 8 mpa.