3D numerical study of geothermal reservoir performance of homogeneous sectors of Mesozoic sandstone formations in the North German Basin developed by smart multi-well systems

Abstract In the context of the heat transition in Germany, the decarbonization of the heating and cooling industry via renewable energy sources requires the usage of comprehensive strategies and novel engineering solutions. With regard to district heating in urban areas, middle-deep geothermal resources offer a great potential which has not been fully utilized yet due to the required minimum temperature on district heating networks. However, the controlling factors on the optimal and sustainable development of those middle-deep geothermal resources are not fully elucidated yet. Within the ArtemIS project, we systematically analyze the impact of reservoir quality and operational controlling factors on the performance of homogeneous sectors of Mesozoic sandstone reservoirs in the North German Basin (NGB) targeted by smart multi-well arrangements. For the first time, we compare in a comprehensive manner previous analytical results with our numerical findings to quantify the influence of different controlling factors on the thermal breakthrough occurrence time, the maximum cooling rate after the occurrence of the thermal breakthrough and the end production temperature. Moreover, we especially focus and illustrate the controls on the behavior of the production temperature after the thermal breakthrough has occurred and conduct a parametric analysis with regard to the thermal utilization time or life span of a geothermal facility. Based on our numerical results, we set up a ranking scheme showing the influence of varying controlling parameters on the considered performance parameters. Our comprehensive numerical study therefore illustrates in detail the complex thermo-hydraulic interaction of geothermal doublet arrays, the controls on the defined thermal lifetime as well as the optimization possibilities of middle-deep geothermal resources. Ultimately, numerical experiments demonstrate that the heat demand of towns and villages in the NGB can be met to a large extent by middle-deep geothermal energy in an optimized sustainable way.