Impacts of Fracture Properties on the Formation and Development of
Stimulated Reservoir Volume: a Global Sensitivity Analysis
Abstract
Stimulated reservoir volume (SRV), the high-permeable fracture network
created by hydraulic fracturing, is essential for fluid production from
low-permeable reservoirs. However, the configuration of SRV and its
impacting factors are largely unknown. In this work, we adopt the
stochastic discrete fracture network method to mimic natural fractures
in subsurface formations and conduct a global sensitivity analysis with
the Sobol method. The sensitivity of different fracture properties,
including geometrical properties (fracture lengths, orientations and
center positions), mechanical properties (fracture roughness and
fracture strength), fracture sealing properties (probabilities of open
fractures and segment lengths) and the fracture intensity, are
investigated in two and three-dimensional fracture networks. JRC-JCS
model is adopted to identify critically stressed fractures. We find that
critically stressed fractures compose the backbone of SRV, while
partially open fractures can significantly enlarge the size of SRV by
connecting more critically orientated fractures. The fracture roughness
is the most influential factor for the total length (area) of critically
stressed fractures. For the relative increase of SRV (RI) in 2D/3D
fracture networks, the probability of open fractures is the most
significant factor. The fracture lengths and center positions are
essential factors for RI in 2D fracture networks but insignificant in 3D
fracture networks. This work provides a realistic scenario of the
subsurface structure and systematically investigates the influential
factors of SRV, which is useful for estimating the size of SRV and
predicting shale gas reservoirs’ production in an accurate and
physically meaningful way.