Evaluation of Current Stress State and Critically Stressed Faults
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.