Fracture Modes in the Silurian Qusaiba Shale Play, Northwest Saudi Arabia and their Geomechanical Implications

Fracture studies were conducted for unconventional prospect evaluation in the Silurian Qusaiba Shales, northwestern Saudi Arabia. Borehole image logs, oriented cores, seismic, and drilling observations were used in the studies. The fractures include natural fractures and induced fractures. The induced fractures (drilling-induced tensile fractures and breakouts) are a manifestation of borehole deformation due to in-situ stresses and were studied to assess the stress regime in terms of directions and magnitudes. The results show that the present day maximum horizontal in-situ stress trend varies from NNW-SSE to NNE-SSW, and show a regional pattern dominated by the Arabian plate tectonics.