Laboratory Experiment of CO2 Huff and Puff in Tight Reservoir and Determination Method of Development Parameters for CO2 Huff and Puff Development

CO2 huff and puff is one of the effective methods to improve reservoir recovery. For tight reservoirs, the research on the development mode and development parameters of CO2 huff and puff is insufficient. Through the laboratory experiments of CO2 huff and puff, the difference between the mechanism of CO2 flooding and that of CO2 huff and puff was analyzed. The relationship between the amount of CO2 injection and the solubility of CO2 in formation crude oil was studied. The influence law of the sweep volume of CO2 by the stuffing time was clarified. Finally, the method of determining the development parameters of CO2 huff and puff was established. The results show that the main mechanism of CO2 flooding to improve oil displacement efficiency is to reduce interfacial tension and displacement resistance, while the mechanism of huff and puff is to maximize the solubility of CO2 in crude oil, so it is not necessary to form miscibility in CO2 huff and puff. When CO2 injection rate is lower than CO2 dissolved in crude oil, better oil displacement effect can be obtained. If the injection rate is too high, the development effect will become worse. The development effect of CO2 huff and puff in closed reservoir is better. If the reservoir is not closed, the development mode of small injection volume, multiple rounds and supplementary supply can be adopted