Calculation of 3D Reservoir Rock Mechanical Parameters of Metamorphic Rock Reservoirs in the Bozhong 19-6 Gas Field of the Bohai Bay Basin and Their Significance

Zhang Guanjie; Cheng Qi; Zhang Lei; Liu Wenchao; Zhao Yujia; Wu Hao; Shen Chuanbo

doi:10.3799/dqkx.2023.195

Abstract：Triaxial compaction test,Brazilian test,and triaxial shear test were conducted to characterize the rock mechanical parameters of buried-hill reservoirs in the metamorphic rocks of Bozhong 19-6 gas field in Bohai Bay Basin and to provide reliable basic data for subsequent numerical simulation of ground stress field and reservoir fractures in this region.Single-well dynamic rock mechanical parameters were computed using array acoustic curves,and the single-well distributions of static rock mechanical parameters were determined via dynamic-static calibration;Prestack seismic multiattribute detection was adopted to deterministically inverse 3D heterogeneous rock mechanical fields and clarify the spatial distribution of rock mechanical parameters.On this basis,physical property test,whole-rock mineral analysis and mercury intrusion testing data were used to analyze the main control factors on the rock mechanical parameters.Then the fracture development index and lithological identification charts were built using static rock mechanical parameters.It was found the metamorphic buried-hill reservoirs in Bozhong 19-6 gas field of Bohai Bay Basin had Young's modulus within 20 to 60 GPa,Poisson's ratio within 0.15 to 0.25,tensile strength within 5 to 15 MPa,and internal friction angle within 30° to 50°.The horizontal distributions of the rock mechanical parameters were highly heterogeneous,and their vertical distributions were mainly related to tectonic properties and the weathering effect,and reflected the physical properties of reservoirs to some extent.Reservoir physical properties,concentrations of different minerals,and pore radius were the main controlling factors of the rock mechanical parameters.The metamorphic buried-hill reservoirs were featured by well-developed fractures,and complex lithology,and the reservoir fractures and lithology cannot be accurately identified using routine methods.In comparison,the fracture development index,and lithological identification charts built on basis of static rock mechanical parameters are significant in guiding the evaluation of fracture development degree and complex lithologic division in metamorphic buried-hill reservoirs.