Abstract

Microearthquakes (microseismic events) are induced during hydrocarbon and geothermal fluid production operations in naturally fractured reservoirs. They typically result from shear-stress release on pre-existing faults and fractures due to production/injection induced perturbations to the effective stress conditions. These stress changes may be due to reservoir depletion, flooding or stimulation operations. Over a number of years it has been shown that microseismic monitoring has the potential to provide valuable time-lapse 3D information on the geomechanical processes taking place within a reservoir. These processes include the distribution of fluid flow and pressure fronts within naturally fractured systems, production-related compaction and the reactivation of faults. With the advent of permanent reservoir monitoring systems (e.g. intelligent wells) microseismic monitoring has the potential to become a practicable means of time-lapse imaging of hydrocarbon reservoir processes remote from production/injection boreholes. This paper illustrates some of the ways in which microseismic monitoring can contribute to the development and management of hydrocarbon reservoirs through the presentation of examples from both hydrocarbon and geothermal reservoirs.