Characterization and Evaluation of Effective Fractures in the Second Member of the Xujiahe Formation in the Xinchang Deep Tight Gas Reservoir

Abstract

AbstractThe development of effective fractures is the main controlling factor of high production in deep tight gas reservoirs, and the key to realize effective production of undeveloped reserves is to make clear the distribution of effective fractures. In this paper, taking the second member of the Xujiahe formation (T3x2) in the Xinchang deep tight gas reservoir as an example, the types and characteristics of effective fractures are clarified, the main controlling factors of effective fracture development are clarified, the effective fracture development mode is established, and the effective fracture characterization technology is formed. The results show that: (1) five types of fractures are mainly developed in T3x2, including flat fracture, low angle fracture, inclined fracture, high angle fracture and vertical fracture, among which inclined fracture, high angle fracture and vertical fracture are the effective fracture types, which have the greatest impact on productivity; (2) the development of effective fractures is mainly controlled by external and internal factors. The closer the fracture is, the greater the fold curvature is, the more developed the effective fractures are, the higher the quartz content is, and the moderate thickness of single layer is, the more developed the effective fractures are. (3) based on the multi parameter analysis of logging, the curves of acoustic wave and electrical resistance are sensitive to fractures. On the basis of logging evaluation, combined with the entropy attribute of geophysical structure, the effective fractures can be quantitatively characterized.KeywordsEffective fractureMain controlling factorGeological modelQuantitative characterizationDistribution evaluation