The use of natural resources long after the discovery of fossil resources became exceedingly popular. Extraction more economical is important as a human priority. Using too much of these vessels and using low-pressure reservoirs are unavoidable. Human thought-provoking fell so low-pressure reservoirs. Including the ways in which the process of hydraulic fracturing is used to stimulate reservoirs. Given the high cost of this process, experimental and numerical modeling, especially after the human understanding of fracture mechanics was developed. Two-dimensional models, pseudo three-dimensional models and three-dimensional models based on the interaction of fluid and rock expanded. Most of these models are based on the elastic behavior of bedrock developed and acceptable results in hard rock were shown. However, bedrock reservoirs (eg, soft shale) are not always hard and may be sometimes soft and show inelastic behavior. In order to investigate the inelastic behavior of bedrock, Mohr-Coulomb and Bounding Surface behavioral modeling were used to simulate this process in the predefined and arbitrary crack path. Also, the new crack initiation function were defined to simulate crack tip more realistic. For this purpose Abaqus software packages and Fortran to load Subroutine used for modeling. Results show significant differences in terms of geometry and elastic behavior with elasto-plastic. In general, the more plastic behavior, the more fracture pressure in the reservoir, larger crack width and length is less. In addition, it seems Bounding Surface model predicts the larger width compared to elastic and Mohr-Coulomb in the first stage of the crack, however by propagating crack in the last stage, Mohr-coulomb estimated the larger crack opening. Furthermore, Higher stress distribution was established in case of Bounding surface model against other behavioral modeling. Key Words Hydraulic fracturing, numerical modeling, Elastoplastic, cohesive zone, Extended finite element, Mohr-Coulomb criterion, Bounding Surface, Abaqus software
