Dynamic Development Characteristics of Shale Oil Reservoir Pores in Dongying Depression

In order to explore the change of pore structure during the development of matrix and laminated reservoirs and to determine the factors affecting the reservoir physical properties on the recovery factor. On the basis of the pore pressure rise experiment and the pore pressure drop experiment, the core porosity change was quantitatively characterized by the nuclear magnetic resonance T2 spectrum testing technology, and the dynamic change process of shale pore structure and the influencing factors of shale oil elastic recovery were studied. The results show that when the pore pressure increases from 4 MPa to 20 MPa, the porosity increases to 127% –154% of that of 4 MPa, and when the pore pressure decreases from 20 MPa to 4 MPa, the porosity decreases to 62% –84% of that of 20 MPa, indicating that the reservoir stress sensitivity is strong. In the process of reservoir development, fluid flows in shale pores are complicated, and there are mutual flows between large pores, small pores and small pores. When pore pressure decreases from 20 MPa to 8 MPa, the elastic recovery factor of core is 11.55%  –22.04%. For the laminated core, the boundary constraint on the fluid is reduced due to the existence of fractures, and the seepage capacity of the core is enhanced, which is manifested as low starting pressure gradient, high permeability, strong seepage capacity and high elastic recovery. This study reveals the dynamic changes of pores in the shale development process, which helps decision-makers to understand the influence factors of permeability and starting pressure gradient on the elastic recovery factor, and provides a reference for the formulation of reasonable development technology.