Thermal-Hydrological-Mechanical-Chemical Modeling of the 2014 EGS Stimulation Experiment at Newberry Volcano, Oregon

Abstract

A 3-D Thermal-Hydrological-Mechanical-Chemical (THMC) model of the EGS Demonstration Site at Newberry Volcano was developed and refined using data from low-pressure injection tests in 2010 and 2013 and a prior stimulation test in 2012. Simulations of the field tests were performed using TOUGHREACT V3-OMP (Sonnenthal et al., 2014; a parallel THC code) and TOUGHREACT-ROCMECH (Kim et al., 2012; THMC code). In addition to full multiphase reactive-transport capabilities, TOUGHREACT-ROCMECH also couples thermohydromechanical rock deformation (poroelasticity), shear and tensile failure, with coupling to porosity and permeability changes. Simulations captured the detailed in-situ temperature profiles and wellhead pressures, as well as the effects thought to have resulted in the overall spatial distribution of microseismicity. The refined 3-D model was then used as a basis to evaluate processes and planning for the 2014 Stimulation Test. Starting in September 2014, injection into Well 55-29 was repeated after installation of a new casing and a perforated liner in the open well section. Although there are data currently for only the first week of the experiment, the model has captured injection rates and borehole temperatures quite closely, and important aspects of the early injectivity increases owing primarily to THM effects. Detailed simulations and analysis of the full experiment will be presented at the 2015 Workshop.