Development of Geomechanical Earth Model for New Wells with High Deviation Trajectory Plans in South of Iraq

The southern Iraq region has the privilege of having a group of the most important oil fields in the world. More than 3000 wells have been drilled in this region with different well designs, presenting major wellbore instability issues that includes caving, hole pack-off, stuck pipe and logging tools, hole enlargement, during drilling operation. Proper designing for any drilling campaign in these fields is the main step for achieving the targeted goals. Drilling the first boreholes with high deviation trajectory plan and new well completion design will require a consolidate geomechanical model as an essential tool for assessing drilling integrity, and guiding future well planning non-productive time. The main objective of the current study is to construct high resolution 1D mechanical earth model (MEM) for new highly deviated trajectory plan developed recently in one of the fields using a wide array of input and calibration data. The generated 1D model was utilized to examine the Wellbore Stability using different failure criterion methods for evaluating drilling problems related to instability when penetrating through weak formations, then to determine the safe window of the mud weight for the wells with deviation above 75 degrees. These analyses highlighted the change in drilling stability with well azimuth and inclination, which showed that drilling highly deviated borehole in the direction of minimum horizontal stress is different in the case of drilling with maximum horizontal stress direction The telling conclusion—from all the field observations collected so far and the 1D results obtained—is the need for raising mud weights and change the casing design in the highly deviated wells. The drilling campaign for future deviated wells in the studied filed improved by designing optimal mud weight and casing programs for any given wellbore trajectory. Results and observations from this study, helps in designing the current and future drilling campaign by designing the optimal mud weight programs for any planned trajectory and drilling practices, and serves as a base for planning deviated wells aiming to reduce nonproductive times and increased drilling efficiency.