Numerical Modeling of Potential CO2-Fed Enhanced Geothermal System (CO2-EGS) in the Gorzów Block, Poland

This article presents the results of numerical modeling for a hypothetical CO2-EGS system in the volcanic rocks of the Gorzów Block, Poland. Modeling was carried out in the following stages: in phase 0, modeling of the fracturing process was performed, as a result of which the permeability distribution for the newly created fractured zone was obtained. Next, the process of saturating the EGS reservoir with CO2 was modeled until pure CO2 could enter the production well (phase 1). Then, a multi-variant simulation of heat production was performed (phase 2). The obtained results allowed for drawing interesting conclusions: (1) the duration of phase 1 may take several years unless a sufficiently high injection rate of CO2 is supplied, (2) the higher the injection rate of CO2, the lower the cumulative storage ratio of CO2, and (3) most of the CO2 storage in the formation takes place in phase 1, while even 92% of the CO2 injected in phase 2 can be recovered via the production well. Despite the environmental benefits connected with structural trapping of CO2, the Gorzów Block has probably too low formation temperature (145 °C) and too low stimulated volume (~0.1 km3) to deliver satisfactory and stable thermal output.