Numerical Simulation of Geothermal Extraction for Interaction between Irregular Curve Fractures and Heterogeneous Reservoirs

The irregular bending shape of fractures and reservoir heterogeneity have a negative impact on geothermal exploitation. In this paper, a new three-dimensional numerical model of geothermal extraction is developed. The heterogeneity of multiple physical parameters of the reservoir is described by spatial frequency, and irregular curve fractures are constructed by combining the Weierstrass–Mandelbrot (W–M) fractal function. Finally, the influence of the dominant parameters representing the bending degree of fractures on the heat extraction effect of the reservoir is emphatically analyzed. The results indicate the presence of a clear cross-flow phenomenon in the actual heat recovery process, with the primary channel resembling "branches". As the fractal dimension increases from 2.1 to 2.3, the produced energy rises by 11.63%, and the effective electric power increases by 16.01%. When the fractal dimension exceeds 2.3, it has little effect on the heat recovery performance. When the fractal roughness increases from 10^–7 to 10^–2, the produced energy decreases by 7.75%, and the effective electric power decreases by 10.64%. The smaller the fractal dimension, the larger the fractal roughness, and the earlier the thermal breakthrough. The research results are of great significance for accurately evaluating the heat recovery effect of related geothermal reservoirs.