Evaluation of Current Stress State to estimate the potential of fault reactivation
For oil, gas and geothermal reservoirs as well as underground storage caverns, re-activation of pre-existing faults can pose severe consequences such as induced local seismic activities. When the faults become hydraulically conductive, a breach of geocontainment may occur, causing undesired migration of subsurface gasses, steam or other fluids. Therefore, it becomes vital to evaluation the current stress field, assess the stability of pre-existing faults/fractures, and determine the conditions that can result in critical stress state of such faults/fractures. When faults or fractures are critically stressed, they are under high shear stress that potentially leads to shear slip, dilation and enhanced permeability.
This study may involve a combination of the following assessments:
Cased-hole logging (such as temperature and spinner logs) to detect flow-induced anomalies fractures
Core and open-hole/image logs analysis to identify hydraulically conductive faults/fractures
Open-hole mini-fracs to determine the minimum in-situ stress and maximum horizontal stress
Static pressure measurement to obtain current pore pressure
Caprock core testing for rock properties, strength and failure criteria
Geomechanics modelling to simulate various in-situ conditions
Geomechanics consulting to identify the stress regime, current stress state, the critical stress state, and recommended changes to operational parameters, etc.