Summary
Understanding and modeling the coupling between hydraulic fracture propagation and natural fracture networks is critical to evaluate potential resources of low-permeability reservoirs. In this work, we present a method to build connected networks from microseismic events. The connections between the microseismic events are established using chronological time to iteratively expand the network. Connection criteria can include a combination of microseismic events, reservoir, and network attributes (e.g. magnitude, length of network branches, stress, anisotropy, natural fracture orientations, etc.).
The resulting network exhibits realistic shapes of growth patterns. New attributes such as sinuosity, branch index and distance to treatment interval along the network, are calculated and enable to better understand and characterize possible hydraulic fracture propagation.
The drainage volume and area of the resulting network are estimated at no extra computational cost. They are significantly less than traditional stimulated reservoir volume (SRV) estimated from methods that use shapes fitted to the 3D microseismic event cloud or methods based on gridded volumes as these are strongly dependent on the support at which they are calculated.
These networks provide a convenient way to efficiently perform sensitivity analysis with respect to the impact of miscroseismic events positions and attributes; as such they offer a wider understanding of the uncertainty in the propagations of hydraulic fractures that could be used to design subsequent microseismic surveys, fracturing jobs and well spacing. Network extent, height, and aperture can be estimated through calibration with treatment attributes such as injected proppant volumes.
