numerical and analytical study of reservoir geomechanics model for underbalanced drilling in sandstone formations

This paper focuses on the application of numerical and analytical modeling for feasibility study of under balanced drilling (UBD) in oil field and in sandstone formations, which has been used for one-dimensional analysis of Geolag software. In the analytical solution section of elastic and plastic relations of wall stability, different relations have been used. heavy costs imposed on the oil industry in Iran due to drilling in reservoirs with sandstone formation, which are characterized by cracks and the presence of shale layers, understanding the mechanism of failure and the reaction of this environment has made drilling inevitable along with providing a suitable solution to minimize these problems. oil field is one of the major fields in southwestern Iran, which is always associated with the problem of loss and the problems of wellbore stability. Drilling reports and logs prepared from these well show that in oil well, the pressure of drilling mud on the wall is 33 MPa, and due to this amount of mud pressure, the wellbore stability along the well path is somewhat and risky. Wall collapse is provided. The simulation is performed with a one-dimensional model of Geolag and analytical solution that the most unstable reservoir layer in oil well according to the mud pressure used, the well mud shows an unsafe environment in terms of stability, which is used by drilling mud pressure correction and Determining the safe drilling mud window. which allows the use of under balanced drilling. According to the obtained results, for feasibility study of under balanced drilling, it was determined to determine the optimal mud and optimum mud pressure for under balanced drilling.This amount of modified mud pressure in oil well in the over balanced drilling method is 43.90 MPa, which is 37 MPa in the under balanced drilling section of oil well