Research on the Mechanism and Technical Limits of Huff and Puff in Natural Water Drive Reservoir

Carbon dioxide huff and puff technology is widely used in X oilfield. At present, there are many kinds of huff and puff technologies in the field, but the oil increasing mechanism of different huff and puff technologies is not clear. The scope of application and the timing of replacement need to be further studied. Based on the classification and evaluation of natural water drive reservoir in X oilfield, this paper establishes an abstract geological model, uses laboratory experiments and numerical simulation methods to carry out research on the oil-increasing mechanism and technical limits of different huff and puff technologies. Combined with reservoir engineering theory, the index of movable oil recovery degree is proposed to clarify the dimensionless limits of different huff and puff technologies. The results show that the three huff and puff methods of carbon dioxide huff and puff, composite huff and puff and deep huff and puff have obvious effect of water control and oil increase. When the movable oil recovery degree is between 26% and 45%, the carbon dioxide huff and puff is the best. When the movable oil recovery degree is between 45% and 58%, the composite huff and puff is the best. When the movable oil recovery degree is between 58% and 77%, the deep huff and puff is the best. The research results can effectively guide the differential design of precise huff and puff in natural water drive reservoir, and have a good prospect of popularization and application.