Numerical simulation of hydraulic fracturing and associated microseismicity using finite-discrete element method

TLDR

Hydraulic fracturing enhances connectivity of low‑permeability reservoirs by injecting fluid to create fracture networks, and microseismic monitoring evaluates this stimulation. The study uses a combined finite‑discrete element method to numerically simulate hydraulic fracturing and its associated microseismicity. Post‑processing with frequency‑magnitude distribution, fractal dimension, and a non‑parametric clustering algorithm reduces mesh dependence and extracts realistic seismic information from the FDEM results. Simulations show that locally fractures follow rock discontinuities, while at the reservoir scale they develop parallel to the maximum in‑situ stress.

Abstract

Hydraulic fracturing (HF) technique has been extensively used for the exploitation of unconventional oil and gas reservoirs. HF enhances the connectivity of less permeable oil and gas-bearing rock formations by fluid injection, which creates an interconnected fracture network and increases the hydrocarbon production. Meanwhile, microseismic (MS) monitoring is one of the most effective approaches to evaluate such stimulation process. In this paper, the combined finite-discrete element method (FDEM) is adopted to numerically simulate HF and associated MS. Several post-processing tools, including frequency-magnitude distribution (b-value), fractal dimension (D-value), and seismic events clustering, are utilized to interpret numerical results. A non-parametric clustering algorithm designed specifically for FDEM is used to reduce the mesh dependency and extract more realistic seismic information. Simulation results indicated that at the local scale, the HF process tends to propagate following the rock mass discontinuities; while at the reservoir scale, it tends to develop in the direction parallel to the maximum in-situ stress.