Research progress of microscopic percolation mechanism of shale oil

Abstract

Shale oil has become the focus of the exploration and development of unconventional oil and gas resources in the world, but its development faces many challenges. Aiming at the complex pore space, the unclear percolation mechanism, and the urgent need to explore research methods of shale oil, this paper systematically expounded the research status of microscopic percolation mechanism of shale oil in experimental methods and computational simulation, and discussed the existing problems and the development trend of future research from the perspective of pore-scale and core-scale. The results show that the combination of various experimental methods can well characterize the pore structure of shale, but the characterization of micro-scale and core-scale flow is still insufficient. The direct method represented by Lattice Boltzmann Method and the indirect method represented by pore network simulation are the main methods to study pore-scale flow mechanism, but the consideration of micro-scale effect needs to be improved. The study of core-scale flow mechanism is mainly to establish a percolation model considering boundary layer effect based on capillary bundle model and fractal theory. It is pointed out that the main future research direction is to fully consider the factors such as boundary adsorption/slip, density/viscosity heterogeneity, stress sensitivity, start-up pressure gradient of shale oil in micro-nano pores, realize multi-scale percolation mechanism coupling, and establish a mathematical model that can accurately characterize the multi-phase and multi-scale flow of shale oil.

Keywords

• pore network model (pnm)
• lattice boltzmann method (lbm)
• digital core
• nonlinear percolation
• percolation mechanism
• shale oil