Sealing performance evaluation of fault fracture zone of different structures based on geomechanical methods: a case study in M area, Chezhen Sag, Jiyang Depression, Bohai Bay Basin

Fault sealing performance is an important control on the distribution of oil and gas reservoirs. A shattered fault zone can be identified easily in outcrops but difficult in the subsurface. Some fault fracture zones were identified and the development patterns were classified. Dynamic rock mechanical parameters were obtained from well logging data, and then corrected according to the rock static parameters obtained by triaxial stress experiments. Finally, using the Ansys software, a numerical simulation of the sealing coefficients of fault fracture zones in three development modes (fault gouge, fault breccia and induced fracture zone) was carried out. The development mode of the fault fracture zone in M area was divided into the fault fracture zone with only fractures developed, the undeveloped fault gouge and the fault fracture zone with a complete structure. The fault fracture zone with a complete structure shows the best sealing performance, followed by the fault fracture zone where the fault gouge is not developed. The fault fracture zone with only fractures developed shows the worst sealing performance. They are mostly open faults, and the fracture zone often becomes an oil and gas migration pathway.