Feasibility of Heat Production from Salt Domes Using Next-Generation Closed-Loop Geothermal Systems

Abstract Rock salt (halite) has significantly higher thermal conductivity than other rocks and thereby can serve as a superior geothermal reservoir, yielding higher heat production. There are several salt domes in the Gulf of Mexico and North Sea that can be used for geothermal energy production. However, traditional open-loop geothermal systems (OLGSs) are not suitable for geothermal energy production from salt due to wellbore instability, corrosion, scaling, etc. To address this issue, this study proposes closed-loop geothermal systems (CLGSs) as an alternative to OLGSs for heat production from salt. First, a three-dimensional hydrothermal coupled model is established for CLGSs in a salt dome. Then, we evaluate the heat production performances of multilateral CLGSs in a salt dome under various conditions, including lateral numbers, lateral level numbers, and flow rates. Results show that horizontal laterals can effectively improve CLGS heat production from salt, and heat production improvement increases with the lateral number at a diminishing rate. Incorporating eight laterals connected to the vertical well bottom of a CLGS increases its after-20-year outlet temperature and thermal power by 83 °C and 713%, respectively. Also, vertically stacked laterals bring more heat production than only one level of laterals. However, the performance of stacked laterals is highly dependent on the flow rate. The number of lateral levels and flow rate have a synergic effect on heat production.