A Three-Dimensional Thermal-Poroelastic Model for Natural Fractured Geothermal Reservoir Stimulation

摘要

One of the most important tasks for geothermal reservoir development is engineering a fractured reservoir and predicting its future performance. For this purpose, numerical modeling of fluid flow and deformation of fractured rock under thermal-hydra-mechanical (THM) interaction is necessary. This work focuses on utilizing a stochastic fracture network to simulate the THM response of the reservoir during the stimulation process, and to assess the permeability enhancement in the stimulated zone. A system of stochastically-distributed fractures is introduced into rock blocks in current model. The effect of the fractures on permeability is evaluated using the equivalent permeability approach. The rock matrix is assumed to be poroelastic and the factures are allowed to deform and to slip. Heat transport within the fractures, and heat conduction between adjacent rock matrix and the fluid in the fracture are also considered. A series of simulations are carried out to analyze the rock mechanical response and permeability evolution for a Newberry-type reservoir. Results show the significant role of fractures distribution and their mechanical response in EGS design and development. This model provides a tool to predict the performance of natural fracture networks, and to analyze the stimulation response and future production performance.