Using geomechanics to optimize field development strategy of deep gas reservoirs in Saudi Arabia

Saudi Aramco has embarked on drilling long horizontals and maximum reservoir contact (MRC) wells in the deep gas reservoirs. Regional stress field is playing an important role in predicting wellbore stability and future production performance of these wells. To successfully drill and produce these long horizontal wells a detailed geomechanics study and its results needed to be incorporated in the decision tree. Reservoir Management was keen to find the optimum azimuthal direction to place horizontal wells, which will minimize the risk of hole breakouts, optimize drilling mud weights, and ensure sustainable production under depletion mode. A study was undertaken to study the effect of geomechanics on drilling and production of these gas wells. Drilling and production histories along with laboratory measurements were incorporated in the study. The study concluded that horizontal wells should be drilled parallel to the locally derived maximum principal stress (S_Hmax) azimuth to maximize borehole stability and minimize required mud weights during drilling and production. To date a substantial number of wells have been drilled in the field following the recommended drilling direction that would ensure minimum damage to the reservoir and well's productivity. The objective of the paper is to illustrate methodologies employed to find the optimum drilling direction causing the least damage to the reservoir and discuss implementation of its findings in the field development.