Facies-controlled geomechanical modeling for horizontal stress prediction in the Lower Cambrian carbonate reservoir, Sichuan Basin, China

Accurate horizontal-stress prediction in carbonate reservoirs is challenging because mechanical properties commonly vary over short vertical intervals as a result of lithologic heterogeneity, diagenesis, pore development, and fracture distribution. This study develops a facies-controlled geomechanical workflow for the Lower Cambrian Canglangpu Formation in the Sichuan Basin, using integrated mineralogical, petrographic, image-based, acoustic, strength, Kaiser-effect, and well-log data from four wells. The formation was partitioned into three mechanically meaningful facies because the laboratory and image-derived data demonstrate that it is mechanically nonuniform and cannot be reliably represented by a single linear elastic transform or one interval-wide model. The defined facies include a carbonate-dolomite compact to moderately porous facies, a mixed sandy-dolomitic dissolution facies, and an argillaceous tight mixed facies, each reflecting distinct local mechanical behavior. Facies-specific static properties and dynamic-to-static transforms were assigned from triaxial and uniaxial compression data where available, while Kaiser-effect stress measurements were used to calibrate horizontal strains within a poroelastic framework. The calibrated model was then extended continuously through conventional well logs to predict maximum and minimum horizontal stresses. Results show that facies partitioning provides a geologically defensible means of capturing local stiffness and stress variations in a heterogeneous carbonate interval, especially where laboratory data are unevenly distributed among facies. Sensitivity analysis further indicates that variations in the assumed Biot coefficient affect stress magnitudes but do not change the overall facies-controlled stress architecture. The proposed workflow therefore offers a practical approach for stress evaluation and borehole-stability screening in mechanically heterogeneous carbonate reservoirs.