Well Bore Stability Analysis Of Field XYZ In Lower Indus Basin Pakistan

Wellbore instability problems significantly increase the cost of drilling and operations in the oil and gas industry.These problems can occur in a variety of forms including stuck pipe,loss circulation,hole enlargement,unintentionally induced tensile fractures or difficult directional control incidents.In this research,we investigate the wellbore instability issues in oilfield XYZ,lower Indus basin,Pakistan,a developing oil and gas sandstone reservoir located in Sind province,Pakistan.An integrated wellbore-stability study was implemented to help avoid wellbore instability problems in this field.To narrow down the possible causes of wellbore instabilities in this field,a problem diagnostic scheme was done by analyzing well log data,drilling reports,mud logging reports,and pore pressure measurements.The availability of data is the main problem in developing a good geomechanical model.Numerous methods for data acquisition were discussed in this study to gather reliable geomechanics data as inputs for the model,especially log based methods.MohrCoulomb and Mogi-Coulomb failure criteria are used to predict the breakout profile and to estimate the optimum mud weight to avoid wellbore collapse as well as sticking.Moreover,the wellbore failure analysis demonstrates the necessity of core analyses and field tests such as the triaxial test and the mini-fracture test to improve the geomechanical model when studying lithology with high heterogeneity.