Understanding the created fracture geometry is key to the effectiveness of any stimulation program. However, almost all predictive models used by reservoir and production engineers to estimate recovery in stimulated wells are based on assumptions that naturally lead to oversimplified fracture geometry.  Several published and unpublished micro-seismic monitoring campaigns reveal that in most cases, hydraulically induced fractures are asymmetric (e.g., one wing of the fracture system is predominantly longer than the other).  This asymmetry is also observed in the vertical plane. This has deep implications on reservoir management. For example, if one knows where most of the depletion occurs (e.g., how does the induced fracture geometry relate to the overall existing drilling and producing field geometry), a production team can improve its infill drilling program and flood to improve production.

Micro-seismic is one of the latest and most accepted technologies allowing reservoir engineers and geoscientists to understand hydraulically induced fractures as well as naturally pre-existing fracture networks in three dimensions.  It uses one or several arrays of sensitive and high-vector fidelity geophones in one or several observation wells at a monitoring distance from the well to be treated. These geophones record the micro-seismic events generated while the formation ruptures during the hydraulic treatment. During the stimulation the micro-seismic events are being recorded along a continuous time-line.  These micro-seismic locations can be determined (as well as other source parameters) and mapped to document how the hydraulically induced fracture system propagates within the pay zone.

Many factors impact the ultimate hydraulically induced fracture system geometry. Understanding this geometry is not only helpful to improve large-scale reservoir management but also to design effective stimulation programs specific to a reservoir.