Channel connection and stimulated reservoir volume estimation derived by the timing, location, and focal mechanism of microseismic events

Abstract

Understanding and modeling channels of high-pressure liquids during hydraulic fracturing and stimulated reservoir volume (SRV) estimation are critical for the evaluation of the fracturing effect and the prediction of oil and gas production in unconventional (low permeability and porosity) reservoirs. In this study, we developed a “focal mechanism-to-event” channel connection criterion based on the timing, location, and focal mechanism of microseismic events, enabling the channel to be perpendicular or parallel to the fracturing plane and more in line with the mechanical properties of rock rupture. We first evaluated the two endpoints of all channels as a set of spatial points, followed by the application of the alpha-shape method to detect the concave hull shape boundary formed by the spatial points. Finally, we calculated the SRV by combining the shapes of the concave hull and Delaunay triangulation. In the experimental simulation, we found that this method could effectively calculate the hull volume, and the detected concave hull included all microseismic events and channels. Ultimately, we applied the channel connection criterion and SRV estimation method to a stage of 3.18 h real fracturing data containing 216 microseismic events. The final calculation revealed a total of 410 connection channels and 4.3154 × 105 m3 SRV, which is more consistent with the expected than the “event-to-event” or “event-to-channel” connection criteria and bin or convex hull SRV calculation methods.