Geomechanical Risk Evaluation of Induced Seismicity from Hydraulic Fracturing and Pressure Operations in the Niger Delta Basin
Abstract
Hydraulic fracturing operations increase the recovery of hydrocarbons from low permeability reservoirs, but the geomechanical effects of induced seismicity due to hydraulic fracturing operations have sparked environmental concerns worldwide. While induced seismicity from fracturing and associated pressure changes (e.g., wastewater injection, reservoir depletion) is documented in tectonically active provinces, its implications remain underexplored in the passive-margin Niger Delta Basin, characterized by unconsolidated sediments, growth fault systems, and overpressured shales. This research focuses on developing a geomechanical framework for assessing the risks of induced seismicity due to hydraulic fracturing operations in the Niger Delta Basin. After conducting an extensive review of induced seismicity worldwide, this research developed a framework for assessing the geomechanical effects of induced seismicity in the Niger Delta Basin, considering the geology of the Niger Delta, which includes growth faults with dips of 50-70°, cohesion of 0-5 MPa, friction coefficient of 0.6-0.85, pore pressure gradient of 0.49 PSI/ft in shales, which increases with depth in high pressure-high temperature zones, and regional tectonic stress, which is low in the Niger Delta. The core methodology employs the Mohr-Coulomb failure criterion, incorporating basin-specific shear stress, cohesion, friction, normal stress, and pore pressure parameters to compute critical pore pressure perturbations required for fault reactivation. Scenarios incorporate pressure changes from stimulation, wastewater disposal, and depletion, yielding basin-tailored thresholds (e.g., approximately 1100–1200 psi increase as a safe limit before slip in analogous deltaic settings). Results indicate large-magnitude earthquakes (greater than M4) are unlikely due to the passive tectonic regime; however, localized fault reactivation, subsidence, and minor geohazards remain possible near optimally oriented growth faults. This work introduces the first Niger Delta-specific fault stability screening tool using Mohr-Coulomb analysis, enabling proactive risk mitigation through basin-adapted pressure management, real-time seismic monitoring, and operational guidelines. These measures support sustainable hydrocarbon development, aligning with collaborative resilience in the evolving global energy landscape.