Beyond the dots in the box - Microseismicity-constrained fracture models for reservoir simulation

Monitoring of induced microseismic events usually results in locations for these events and a geometrical interpretation of these dots in the box. In this study we show how additional information obtained from observed microseismic events, namely the source mechanisms, were used to generate a discrete fracture network. Both volumetric and shear-only source mechanism inversion was carried out on microseismic events from the treatment of a shale gas reservoir in the continental US. The source mechanisms revealed fracture orientations more accurately than could be inferred from microseismic event locations alone. The activity associated with different mechanisms is interpreted as indicating reactivation of existing fractures in the rock. as well as suggesting generation of new fractures. Failure analysis using source mechanisms on individual events allows an integrated understanding of the complex fracture interactions taking place in the reservoir, and also provides a more complete understanding of the stress conditions in the reservoir during the treatment. Fracture orientations. locations, and failure mechanisms are translated into discrete fracture network (DFN) models that can be used to verify the extent and character of the fractures created or reactivated during the fracture treatment, and may ultimately be used to generate fracture flow properties for reservoir simulation.