the sensitivity analysis of biot’s coefficient on the induced stresses around the wellbore in darcy and non-darcy flow regimes

Since measurement of biot’s coefficient in the laboratory is expensive and time consuming, in this article, variations of biot’s coefficient on the induced stresses around the wellbores; i.e. the radial, tangential and vertical stresses is investigated, due to the importance of biot’s coefficient on the effective stresses. because in oil and gas wells in addition to darcy flow in some situations like gas reservoirs and hydraulic fracture technique, non-darcy flow is dominant, so the effect of biot’s coefficient on induced stresses in both darcy and non-darcy flow regimes were investigated. the results show that in darcy flow regime, radial, tangential and vertical stresses created around the wellbore are reduced by increasing biot’s coefficient. in other words, less stresses were created in soil relative to intact rock. also, in non-darcy flow regime by increasing biot’s coefficient radial stress decreased. however, tangential stress increases near the wellbore wall and then it decreases in far distance, but opposite trend was observed for vertical stress. so, the stress change pattern around the wellbore was dependent on their flow regime.solving stress equations for a typical reservoir in both darcy and non-darcy flow regimes, it is concluded that for low draw down pressure the effect of biot’s coefficient variation on induced stresses is not considerable.