The Analysis and Theory Research on the Factor of Multiple Fractures During Hydraulic Fracturing of CBM Wells

The multiple fracture theory is the hydraulic fracturing frontier theory, especially for the coal the fractures, physical and mechanical properties of which is different from homogeneous sandstone. The study of multiple fracture theory is difficult and faces many problems. According to coal rock mechanics and structural characteristics and based on the analysis of stress field of coal near by the hydraulic fracture, The results of the theory study shown that sub-fracture of tension easily formed in the area near the well and sub-fracture of shear formed in the area far from the well more easily in process of coal fracturing. And the paper revealed the development rule of hydraulic fracture.