Fully Coupled 3D Geomechanical and Natural Fracture Modeling for Fracture Propagation Simulation in Unconventional Resources

Abstract

Abstract Hydraulic fracturing is one of the major production enhancement measures for low permeability fractured reservoirs, where a large amount of oil and gas is stored worldwide. In recent years, during the development and research of these reservoirs, it has been found that the hydraulic fractures formed are no longer the single planar fractures produced by fracturing in homogeneous reservoirs, but complex, non-planar, multiple hydraulic fractures are formed, and the post-fracturing production often shows a positive correlation with the fracture complexity. A large amount of hydraulic fracturing diagnostic data indicates that the interaction between pre-existing natural fractures and induced hydraulic fractures is the key condition leading to the formation of complex hydraulic fractures. Simulation of hydraulic fracture extension in fractured reservoirs requires simulation of fluid pressure changes after the intersection of hydraulic fractures and natural fractures, as well as hydraulic fracture steering and other complex conditions. The traditional hydraulic fracture extension simulation models and theories are no longer suitable for such inhomogeneous reservoir conditions, but the relevant theoretical research is still immature and the interaction between hydraulic fractures and natural fractures during hydraulic fracture extension in fractured reservoirs is still not well understood. It is necessary to further develop theoretical research on hydraulic fracture expansion in fractured reservoirs to understand the mechanism and influencing factors of complex fracture formation, in order to promote the development of field development and theoretical research system of similar reservoirs. In this paper, we simulate and analyze the factors influencing hydraulic fracture expansion in fractured reservoirs. Through a series of numerical simulations, we found that horizontal bedding may open up during hydraulic fracturing to form horizontal fractures, and horizontal and vertical fractures intersect each other to form a complex volumetric fracture network; The distribution length of volumetric fractures increases and the distribution width decreases when the horizontal principal stress difference increases, and the aspect ratio of volumetric fractures increases; the distribution length of volumetric fractures decreases and the width increases when the fracturing construction displacement increases, and the aspect ratio of fractures increases. The residual tensile strength of natural fractures increases, the distribution width of volumetric fractures decreases, the distribution length increases, and the aspect ratio of volumetric fractures increases. The research results can provide some reference and reference for the fracture design and construction of fractured reservoirs.