Micro Model Establishment and Numerical Simulation of Supercritical CO2 Filtration in Porous Media of Shale Oil Reservoir

ABSTRACT: Supercritical CO2 fluid has the characteristics of low viscosity, easy diffusion, non-toxic and tasteless. It is considered as an ideal working fluid in the fracturing of unconventional reservoirs such as tight oil and gas and shale oil and gas. However, compared with water-based fracturing fluid, supercritical CO2 has very strong filtration. The filtration of supercritical CO2 in the fracturing process has an important impact on the fracturing effect and the design of surface construction parameters. In the past few years, many experimental and simulation studies have been carried out to understand the filtration of Sc-CO2 in dense and shale formations. Although great progress has been made in the macro modeling of unconventional reservoirs, there is still a lack of research on the numerical simulation of micro seepage law, especially the modeling method and numerical simulation of S c-CO2 micro filtration law in fractured shale oil reservoirs. Through python programming, a method for establishing the micro model of shale oil reservoir with discrete fracture network is proposed. Based on the established micro model, the numerical simulation is carried out by using OpenFOAM calculation software to verify the availability of the model and the feasibility of the method. 1. INTRODUCTION The US energy information administration estimates that the world’s total shale oil reserves are 345 billion barrels, including 75 billion barrels in Russia, 58 billion barrels in the United States and 32 billion barrels in China. Shale oil and gas will be an important field for countries to tackle key problems in the future. Since the "shale gas revolution" in the United States, the shale oil and gas industry in the United States has developed vigorously and the shale oil production has increased rapidly. As of December 2019, shale oil production in seven major production areas in the United States, including Permian , Bakken and Eagle Ford, has exceeded 9 million barrels / day, accounting for 70% of the total crude oil production. In 2019, Saudi Arabia became the world’s largest producer of oil and gas, surpassing the United States in the global oil and gas market.