Numerical simulation by hydraulic fracturing engineering based on fractal theory of fracture extending in the coal seam

According to the fractal characteristics of the porosity of the porous media, as well as the fracture extending in the hydraulic strengthening process, the fractal theoretical relationship between porosity and permeability in the coal seam is established. Furthermore, the fractal calculation models of the fracture robustness and the filtration coefficient of fracturing fluid under the hydraulic fracturing are also built. Based on all of the accomplished studies above, the fracture extended model is set up under the assumed condition of the pseudo-three-dimensional fracture extended model. The geometric parameters of the fracture for the eight CBM wells in the Zhengzhuang block of Qinshui coal basin within Shanxi province were calculated by means of the fractal models. The results show that the fractures' lengths of hydraulic fracture range from 106.8 m to 273.1 m, and the widths range from 3.6 m to 12.7 m in study block. By comparing the calculation results with the different models, it shows that the results of the fractal model fit well with the field measured value, this reflects the applicability of the model to some extent.