Distribution pattern of natural fractures in lacustrine shales: a case study of the Fengcheng formation in the Mahu Sag of the Junggar Basin, China

The Lower Permian Fengcheng Formation in the Mahu Sag develops a set of organic-rich alkaline lacustrine shale strata, which is key area for oil exploration and development. As an important storage space seepage channel reservoirs, natural fractures have impact on enrichment, production development effect. In this study, types characteristics were first analyzed using core, thin section imaging logging data. On basis, combined with distribution single wells, vertical law discussed. Finally, planar evaluated different seismic attributes such as coherence, curvature, likelihood, AVAz. results showed that three are existed, including transformational shear fractures, intraformational open bed-parallel being most developed. degree layers has obvious differences, mainly controlled by lithology brittle mineral content. basalt tuff developed Feng 1 Member, low carbonate content, resulting relatively fracture dolomite argillaceous 2 Member 3 high content brittleness, Additionally, closer to fault, higher plane, zone near main secondary faults, trend oriented E-W direction approximately parallel faults. width largest central southern part study area. These fault-related caused regional stress fields from activity main-secondary