Mode I hydraulic fractures always propagate perpendicular to the minimum principal horizontal stress (Shmin). Multi-fractured horizontal wells are therefore most efficient when drilled parallel to Shmin — a configuration that maximizes fracture surface area and stimulated rock volume.
In practice, acreage constraints, lease geometry, or uncertainty in stress orientation may require drilling at an angle to the optimal azimuth. One notable consequence is the development of asymmetric fractures from heel to toe within a stage — an effect clearly captured in models with stress-shadowing capabilities. This asymmetry has direct implications for drainage patterns and the design of well and cluster spacing.
Between the end-member cases of fully transverse and fully longitudinal fractures, sensitivity to well orientation depends on job size, cluster spacing, well spacing, and stage length. This guide examines how these variables interact and how ResFrac can be used to quantify the impact of off-azimuth drilling on stimulation effectiveness.