Stress Regimes in the Gulf Coast, Offshore Louisiana: Data from Well-Bore Breakout Analysis

Abstract

Maximum horizontal stress (SHmax) orientations were mapped for the northern Gulf of Mexico, offshore Louisiana, using borehole breakouts, which are commonly used by petroleum and drilling engineers to determine the stress regime for well-bore stability analyses and reservoir stimulation. The breakout signal is subtle, but indicates SHmax orientations largely parallel to the strike of the progradational clastic sedimentary wedge, in a general northeast-southwest direction. However, significant anomalies exist in the breakout orientations, the main anomaly being orthogonal to the principal SHmax direction. These anomalies were attributed to local perturbations around faults and salt structures and to the effect of the underlying salt. The correspondence among the orientation of faults, salt intrusions, and SHmax from breakouts with the strike of the clastic wedge confirms the existence of stress anisotropy in the northern Gulf of Mexico shelf sediments. Stress anisotropy is caused by the geometry and orientation of the prograding wedge and its associated gravity-driven extension.