A FEM-CZM Based Coupled Thermal-Hydro-Mechanical Model for Deep Offshore Hydraulic Fracturing

Hydraulic fracture initiation and propagation have been popular topics for research. Hydraulic fracturing research now primarily uses numerical simulation since core size constraints prevent laboratory experimentation. Hydraulic fracturing numerical simulation technology is now developing quickly. Thermal-Hydro-Mechanical (THM) coupling models have been established for deep, high-temperature, high-pressure formations. Nevertheless, the majority of these models are sequential or multi-software collaborative. The former has a substantial calculation error but a high calculation speed and good convergence. The latter increases computation accuracy, but because of its slow calculation speed and challenging software coupling, it has not been easy to adopt as the conventional method. This work unifies the THM coupling fracture problem into a single model using the finite element method and the cohesive zone method (CZM) method. This model is used to carry out numerical simulations of hydraulic fracturing in high-temperature and high-pressure formations. The impact of important variables on fracture initiation and propagation is further investigated. The simulation demonstrates that fracture internal pressure is a key factor in the development and propagation of hydraulic fractures. Injecting low-temperature fluid into the formation will result in an obvious thermal effect and cause the formation to contract. The fracture extension and formation fracture pressures are lowered by the heat effect. With its fast calculation speed and excellent precision, the model developed in this study offers a new approach to the numerical simulation of hydraulic fracturing and can accurately simulate the hydraulic fracturing problem of high temperature and high-pressure formation.