Refrac Candidate Selection Considering Natural Fracture Orientation in the Near-Fault Damage Zone*

A large degree of uncertainty in the characterization of natural fracture density and orientation tends to exist in the overall management of unconventional assets. As a result of this uncertainty, the understanding and application of natural fracture network characterization in reservoir management has tended to be limited and often contradictory between practitioners. As a corollary, this uncertainty extends to refrac candidate selection. In the case of natural fracture plane parallelism with respect to the fault damage zone, the stress field is anticipated to simultaneously drive the formation of faults and fractures within a near concurrent time period. Alternatively, fracture plane orthogonality relative to the fault damage zone manifests away from the strongly non-proportional plastic loading zone after the re-orientation of the stress-field post-faulting. As a result, value exists in evaluating the natural fracture network considering well placement and subsurface mechanical constraints. An integrated Eagle Ford case study is shown which leverages a fault likelihood attribute and petro-elastic modeling (PEM). The fault likelihood attribute is used to spatially characterize natural fractures considering the existence of sufficient correlation between faulting and natural fracture formation. The PEM is embedded in a reservoir simulator and is used to combine dry rock elastic properties with the dynamic determination of changes in saturation. In an integrated workflow, these combined methods support the model-driven time-dependent analysis of refrac candidates linking geophysics to reservoir simulation. Typically, the simulated pressure description alone is insufficient to properly characterize refrac candidates due to the diffusive behavior of pressure. Instead, a novel dimensionless analysis of spatio-temporal saturated elastic properties is used which is more discrete and allows the fine scale characterization. The combination of fault likelihood and PEM in an integrated multidisciplinary analysis exploit geophysics in static and dynamic reservoir models to preserve the subsurface description between seismic attributes and flow simulation.