An integrated model for non-isothermal multi-phase flow, geomechanics and fracture propagation

Abstract

This paper presents a fully integrated poro-thermo-elastic hydraulic fracturing and three-phase black-oil reservoir simulator. Both implicit-pressure-explicit-saturation and fully implicit solution algorithms are presented. The energy balance equation is solved in a coupled manner to calculate the temperature change caused by fluid injection for multi-phase flow including the effects of both conduction and convection. Associated poro-thermo-elastic stresses are rigorously computed and their impact on subsurface stress changes and fracture propagation are discussed.This allows us, for the first time, to implicitly couple 3-D reservoir simulations with the transport and settling of multiple proppants as the fracture propagates, dilates and closes. Fracturing fluid leak-off is modeled explicitly. Thermal and poroelastic stresses are fully integrated based on the coupled solution of the energy balance and the flow and mechanics equations. The new simulator is fully parallelized through domain decomposition with message-passing between domains.The model is first validated with well-known problems with analytical solutions and verified with commercial software. This new simulator is then used to study two field-scale geomechanics and fracturing cases. The first case is the simulation of water-injection-induced fracture propagation by the combined poro-thermo-elasticity effect. The second case presents an integrated simulation of multi-stage, multiple fracture propagation with different types of proppant injected and shut-in with proppant settling. After the creation of the multiple fractures, multi-phase production from the well with fracture closure during long-term production with proppant embedment is simulated.