Evaluation of CO2 sequestration and circulation in fault-bounded thin geothermal reservoirs in North Oman using response surface methods

Abstract

In the past decade, techno-economic feasibility of using CO2 as a working fluid to harvest geothermal energy has been studied and demonstrated in both hot-dry rock and deep brine aquifers. Potential geothermal resources have been suggested by hydrogeological surveys in North Oman area. Many depleting petroleum reservoirs in this area provide excellent candidates as CO2 geologic storage and geothermal reservoirs, considering well-characterized and sealed geological structures and existing on-site infrastructure. In this study, we aim to conduct a comprehensive evaluation of reservoir performances during CO2 sequestration and circulation with possible field conditions in North Oman foreland basin. Continuous response surfaces of performance indicators are developed using 1000 CO2 sequestration-circulation models. Each model input file is assigned a set of values sampled using Latin-Hypercube method from high-dimensional parameter space bounded by ranges of key property parameters of reservoirs, including reservoir dip angle, depth, permeability, thickness, lateral boundaries, bounded fault permeability, and geothermal temperature gradient. Using response surfaces, key performance indicators, including CO2 injection, production, storage, fault leakage, well space, pressure, temperature, produced thermal flux, and lifespan, are quantitatively evaluated corresponding to various reservoir conditions represented by input parameters. The findings provide a quantitative guidance on site selection, geothermal field development and operation, and associated leakage risk assessment and techno-economic analysis for potential CO2 sequestration, geothermal exploration and utilization in North Oman foreland basin and other similar fields.