Numerical Study Of Coupled Thm C Processes Related To Geo Energy Production

Numerical study of coupled THM/C processes related to geo-energy production

In this thesis a parallel simulation platform, namely TOUGH2MP-FLAC3Dplus, was further developed by linking the multiphase multicomponent flow code TOUGH2MP and the further developed geomechanical code FLAC3Dplus for large-scale simulation of the coupled THM/C processes related to geo-energy production. A series of mathematical/physical models were developed and implemented in this platform, including (1) an improved equation of state for CO2-CH4-H2O-NaCl system which considers the effect of salt on phase partition and fluid properties in gas reservoirs; (2) a modified coupling approach for the simulation of hydraulic fracturing in tight geo-reservoirs, which considers the multiphase multicomponent leakoff effects; (3) a thermo-hydro-mechanical model based on a crack tensor for naturally fractured rock masses and faults. All these verified models have been applied in three different case studies, including CO2 enhanced gas recovery (EGR) in the Altmark natural gas field; (2) Hydraulic fracturing in three different types of geo-reservoirs (tight gas, oil and geothermal reservoir); (3) Geothermal energy utilization induced seismicity in Unterhaching. The developed models and the numerical platform can be used to predict the coupled THM/C behavior of rock formations, to optimize the CO2-EGR and hydraulic fracturing in tight geo-reservoirs, as well as reduce the geo-risks related to geo-energy production.

Numerical Study of Coupled THM/C Processes Related to Geo-energy Production

Development of coupled THM models for reservoir stimulation and geo-energy production with supercritical CO2 as working fluid

In this dissertation, two specific numerical models have been developed to address the issues associated with utilization of supercritical CO2, like fracture creation, proppant placement and fracture closure in unconventional gas reservoirs, reservoir stimulation, heat production and CO2 sequestration in deep geothermal reservoirs, respectively. In unconventional gas reservoir, the model consisting of classic fracture model, proppant transport model as well as temperature-sensitive fracturing fluids (CO2, thickened CO2 and guar gum) has been integrated into the popular THM coupled framework (TOUGH2MP-FLAC3D), which has the ability to simulate single fracture propagation driven by different fracturing fluids in non-isothermal condition. To characterize the fracture network propagation and internal multi fluids behavior in deep geothermal reservoirs, an anisotropic permeability model on the foundation of the continuum anisotropic damage model has been developed and integrated into the popular THM coupled framework (TOUGH2MP-FLAC3D) as well. This model has the potential to simulate the reservoir stimulation and heat extraction based on a CO2-EGS concept.