In order to reduce the drilling cycle, it is necessary to improve the applicability of the mechanical specific energy model. In this paper, the mechanics analysis is based on the mechanical energy model proposed by R. Teale, the drilling pressure and torques of the vertical and inclined wells are modified respectively, and the intersection model is obtained. The results show that the vertical power is constant greater than that of tangential power at the same depth. When tthe vertical work is tangled with tangential work, the phenomenon of "venting" reflects the good geological properties of the layer. The merit model can better reflect the bottom, and the mechanical ratio can be more suitable for the evaluation of the physical properties of logging, avoiding the influence of non⁃objective factors on the baseline of the mechanical specific energy ratio model, and enhancing the accuracy of field physical property evaluation.

Using the indoor experimental test, the intervals shale reservoir physical parameters, the rock mechanics parameters and the natural fracture distribution characteristic parameters were studied, and the constitutive models of stress fielddamage fieldseepage field coupling and the failure criteria of the defective rock mass in the process of riverfrac treatment were established. Through the finite element numerical simulation by the softwareComsol, the crack propagation law of formation respectively under tensile and compressive shear stress was analyzed, when the natural fracture system opens, hydraulic fracturing of shale reservoir artificial fracture network can be formed. When hydraulic fracture extended to natural fracture, there has been a marked increase the width of cracks, and hydraulic fracture direction changes, one of the wings extended along the natural fracture on the wing, the other one wing does not. There is obvious mutual interference between natural fracture. Process of multi cracks is developed from a small to a large crack fracture, the final number of cracks depends on the connectivity between the cracks; stress, natural fracture, perforation interval, perforation, dip, construction flow and liquid viscosity, are the main factors that influence the formation of multi cracks.