Title: A Statistical Approach to Characterizing Reservoir Deformation Through the Collective Behavior of Microseismicity.
Date: Thursday May 5, 2016
Abstract: Working with the premise that the spatiotemporal behavior of microseismic events can reveal variations in rock properties, we move beyond conventional static microseismic interpretations to identify processes that play important roles in the dynamic expansion of a fracture network during hydraulic fracture stimulations. We motivate our work through the understanding that many small microseismic events lead to finite and macroscopic deformation. Our investigation considers whether the macroscopic properties of the fracture system under local dynamic stress conditions and varying rock properties can be extracted through analyzing the collective spatial-temporal growth of events and their properties within different formations. This is achieved by considering that disturbances in the rock and reservoir trigger inelastic deformation as stress and fluid transfer through the rockmass, thereby suggesting that this deformation can be considered as flow. In other words, the characteristics of flow are mirrored in the seismicity and that large fluctuations in stress in the reservoir comprise turbulence in this flow.
Characterization of flow is achieved through the use of dynamic parameters, such as Diffusion Index (direction and rate of seismic activity and associated stress transfer), Fracability Index (susceptibility of a rock mass to fracturing), Stress Index (where seismic flow is hindered by fracture complexity), Plasticity Index (ease with which the reservoir deforms) and seismic efficiency which combines source parameters of microseismic events as a function of their timing and spatial distribution. We test these concepts for microseismicity associated with stimulations in shale plays throughout North America, tie our observations to supplementary field data and identify differences in dynamic parameters as related to the fracture and stress state, and the underlying rock properties. Our findings suggest that dynamic parameters provide for higher-level descriptions of the target formations, the frac growth process and in defining the resultant producing volume.
For more information, please visit the event website.