geomechanical study of one of iranian reservoirs: from mechanical earth modeling to mud window prediction

Investigating the stability of the wellbore wall and controlling pore pressure and mud weight during drilling operation is one of the most important challenges that can be solved with the help of geomechanics. the existence of accurate and appropriate guidance for predicting the weight of drilling fluid and formation pore pressure is very important and can save millions of dollars annually for the industry and governments. there are different methods for calculating the mud window based on empirical relationships. in this research, a mechanical earth model (mem) for one of the offshore reservoirs in southern iran has been constructed and the maximum and minimum allowable drilling mud weight is presented. first, by the use of available petrophysical log data and tests, based on empirical correlations, geomechanical properties of rock were calculated an initial guess for earth model has been prepared. then, using additional information from daily drilling reports, final well reports, final geology reports and end of well reports (ddr, fwr, fgr, eowr) calculated results were modified and corrected. as a result, by implementing a rock failure criterion, the optimal mud weight window has been calculated. in this research, based on the available data, the usual method of building the earth model has been modified and a mechanical earth model has tailored made for three formations. by comparing the final corrected model and the initial guess of mem, the importance of modifying the initial guess model can be acknowledged. the prepared mem may be used for optimizing and selecting the appropriate mud weight at the selected depth in which can reduce future drilling problems and associated risks or extend the upper limit of mud window using wellbore strengthening methods.

geomechanical study of one of iranian reservoirs: from mechanical earth modeling to mud window prediction

investigating the stability of the wellbore wall and controlling pore pressure and mud weight during drilling operation is one of the most important challenges that can be solved with the help of geomechanics. the existence of accurate and appropriate guidance for predicting the weight of drilling fluid and formation pore pressure is very important and can save millions of dollars annually for the industry and governments. there are different methods for calculating the mud window based on empirical relationships. in this research, a mechanical earth model (mem) for one of the offshore reservoirs in southern iran has been constructed and the maximum and minimum allowable drilling mud weight is presented. first, by the use of available petrophysical log data and tests, based on empirical correlations, geomechanical properties of rock were calculated an initial guess for earth model has been prepared. then, using additional information from daily drilling reports, final well reports, final geology reports and end of well reports (ddr, fwr, fgr, eowr) calculated results were modified and corrected. as a result, by implementing a rock failure criterion, the optimal mud weight window has been calculated. in this research, based on the available data, the usual method of building the earth model has been modified and a mechanical earth model has tailored made for three formations. by comparing the final corrected model and the initial guess of mem, the importance of modifying the initial guess model can be acknowledged. the prepared mem may be used for optimizing and selecting the appropriate mud weight at the selected depth in which can reduce future drilling problems and associated risks or extend the upper limit of mud window using wellbore strengthening methods.