Numerical modeling and simulations for techno-economic assessment of non-conventional energy systems

The techno-economic analyses of two non-conventional energy systems -- enhanced geothermal systems (EGS) and natural gas hydrate systems were performed using a numerical simulation approach. These energy systems, which are still in the development stage and not yet commercialized, are characterized by common components, which are surface plant facilities and subsurface fluid flow and heat transfer. This study aims at a better understanding and advanced evaluation of energy potential as well as the economic viability of these systems by the development of new robust numerical models in order to obtain a more realistic representation of the physical systems.;The first part of the study presents a combined model for EGS, developed by integrating a coupled wellbore-reservoir numerical model with the existing techno-economic model GEOPHIRES. The motivation behind this work is the requirement of a more rigorous model which can truly represent an actual EGS system and evaluate its technical and economic performance in a coupled manner. An unsteady state one-dimensional numerical wellbore simulator coupled sequentially with the numerical reservoir simulator TOUGH2-EGS, was added to the GEOPHIRES as a fifth option to the already existing four analytical reservoir models. A case study is presented for the EGS scenario in Morgantown, West Virginia, which demonstrates the applicability of the model and emphasizes the need of a numerical wellbore-reservoir model for more realistic representation and accurate evaluation of the production potential of an EGS reservoir which has a direct impact on its economics.;In the second part of the study, a techno-economic assessment of gas production from gas hydrate deposits in the National Petroleum Reserve Alaska (NPRA) region of the Alaska North Slope (ANS) was performed, as a part of the US Geological Survey (USGS) gas hydrate Life Cycle Assessment program. The fact that no work was done previously on the reservoir characterization and prediction of gas production for any of the gas hydrate prospects in NPRA, forms the primary motivation for these new efforts to investigate the gas production potential of two of the most promising gas hydrate prospects in NPRA region -- Sunlight Peak and Mount Harvard, using numerical simulation technique. The field scale 3D reservoir models were developed using CMG STARS, which fully describes the production design and the response of the gas hydrate fields. Production simulations showed that the Sunlight Peak and Mount Harvard prospects have the potential of producing 1.34 x 109 ST m 3 and 1.22 x 109 ST m3 of gas with the net present value (NPV) of {dollar}15.76 million and {dollar}25.82 million in 15 years, respectively. A single horizontal well configuration was found to be more economically attractive as compared to multiple well configurations. The geomechanical modeling of the two gas hydrate reservoirs showed no concerns about the geomechanical failure of reservoir rock and wellbore due to the dissociation of gas hydrates and depressurization. From the overall analysis of the results it was concluded that Sunlight Peak and Mount Harvard gas hydrate accumulation behave differently than other Class III reservoirs due to their smaller thickness and high angle of dip