| Title | Assessment of the Impacts of Multi-Scale Sedimentological Heterogeneity on Low-Enthalpy Geothermal Energy Production |
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| Authors | Kiley BAIRD, Dan ARNOLD, Florian DOSTER, Sebastian GEIGER, Dmytro PETROVSKYY, Gary J. HAMPSON, Carl JACQUEMYN, Matthew D. JACKSON, Julio Machado SILVA, Fazilatur RAHMAN, Sicilia JUDICE, Mario COSTA SOUSA |
| Year | 2024 |
| Conference | Stanford Geothermal Workshop |
| Keywords | Rapid Reservoir Modelling, low-enthalpy geothermal energy, sedimentological heterogeneity, geological uncertainty, reservoir simulation |
| Abstract | With the increasing demand for sustainable energy solutions to achieve net-zero emission targets, low-enthalpy geothermal developments have emerged as pivotal contributors to the decarbonization of the heating and cooling sector. Geological uncertainty, which is inherent to all subsurface reservoirs but particularly prominent in geothermal systems due to limited data availability and complex subsurface conditions, directly affects resource assessment, risk mitigation and drilling operations. In order to address geological uncertainty, a robust and efficient modelling and simulation approach that analyses a wide range of geological heterogeneity is needed. This allows us to analyze the extent to which multi-scale and hierarchical geological heterogeneities impact heat and mass transport in low-enthalpy geothermal reservoirs, which remains an area of limited understanding. Our study hence aims to conduct a qualitative assessment of the scale at which geological heterogeneity has significant implications on the expected heat flow rates in a low-enthalpy geothermal system situated in a shallow-marine sedimentary reservoir. Utilizing open-access 3D geological models of shallow marine sequences previously designed using the Rapid Reservoir Modelling (RRM) software, we simulate heat and fluid flow and the associated well behavior, considering 1 km spaced geothermal doublets. The geological models capture a wide range of multi-scale and hierarchical sedimentological heterogeneity, varying from centimeters (e.g., bioturbation) to kilometers in length (e.g., geometry of the shoreline). Different well placements were screened efficiently using inbuilt flow diagnostics in RRM prior to performing time-consuming heat and fluid flow simulations using a commercial simulator. Our results show which length-scales of heterogeneity have a more profound effect on low-enthalpy geothermal energy production in shallow marine deposits, and which length-scales can be excluded in reservoir modelling studies. We highlight the importance of using geologically realistic models to capture geological uncertainty in a comprehensive way. We recommend that an efficient screening approach could be beneficial to analyze which sedimentological heterogeneities impact the behavior of a geothermal system most, and which hence need to be characterized with due care so that they can be included reliably in reservoir simulation studies. |