Experimental assessment of enhanced geothermal system potential of partially abandoned or dry oil wells in a sedimentary basin

Abstract

An enhanced geothermal system (EGS) represents a promising approach to sustainable energy generation by harnessing subsurface heat from deep geological formations with low natural permeability. Sedimentary basins—such as the Williston Basin in North Dakota—are considered viable candidates for EGS development due to their broad geographic extent and moderate geothermal potential. Notably, depleted or non-productive oil wells within these basins offer a cost-effective opportunity for EGS implementation as they can be repurposed, thereby significantly reducing the need for new drilling. This study evaluates the feasibility of EGS deployment in McKenzie County, North Dakota. Core samples from five partially abandoned or dry oil wells associated with production from the Red River Formation were obtained from the Core Library of the North Dakota Geological Survey. These samples, spanning the entire thickness of the formation, were sectioned and polished at defined depth intervals for detailed analyses and precise measurements of key reservoir properties critical to geothermal assessment. Several parameters were analyzed to assess the geothermal viability of these wells, including formation temperature, temperature gradient, porosity, thermal conductivity, energy storage potential, and estimated power output via the Organic Rankine Cycle (ORC). The results demonstrate significant depth-dependent variations in thermal and petrophysical properties. Specifically, the depth range of 4000–4500 m is identified as a promising target for EGS stimulation since it is characterized by elevated temperatures, high thermal conductivity, favorable temperature gradients, and sufficient porosity—all essential properties for enhancing permeability through hydraulic fracturing. Furthermore, the calculated energy content and potential ORC power output at these depths indicate that effective geothermal energy extraction is technically feasible. This suggests a compelling opportunity to repurpose existing fossil energy infrastructure—such as abandoned oil wells—for renewable geothermal applications. Overall, the findings of this study underscore the potential of sedimentary formations for EGS development and contribute to advancing low-carbon, diversified energy solutions in alignment with national decarbonization goals.