Numerical simulation and optimization of the in-situ heating and cracking process of oil shale

Abstract

In this paper, the temperature field variation and cumulative oil production rate over time with fracture number, fracture width and gas injection flow rate were investigated using Fluent software. A mathematical model of heat transfer within oil shale and a three-dimensional mathematical model of its in situ heating and fracturing were established. The simulation results showed that Model II had the highest oil shale heating rate at different fracture numbers, being 26.32% higher than that of Model I. When exploring fracture width, Model I completed all fractures in the oil shale region in 190 days. Model IV was 15 days slower than Model I with the heating rate being 7.89% lower, while Model V was 10 days faster than Model I with the heating rate being 5.26% higher. Increasing the fracture width of the oil shale region appropriately could help to increase the oil shale in-situ heating and fracturing rate. Considering gas injection flow rate, the higher the gas flow rate, the faster the increase of the oil shale area temperature and the shorter the time to reach the 10-day peak oil production rate. The peak was also larger and the fracturing of the oil shale area took place more quickly.

Keywords

• chinese oil shale
• temperature field
• heating time
• cumulative oil production rate
• in-situ heating cracking