Integrated sustainability assessment of repurposing onshore abandoned wells for geothermal power generation

As global efforts intensify to mitigate climate change through Net-Zero by 2050, the transition from fossil fuels to renewable energy sources is of utmost importance. Within this context, geothermal power generation is an underestimated yet rapidly developing field with immense potential. A notable opportunity arises from repurposing abandoned oil and gas wells (AOGWs) as alternative sources for geothermal power production. This study employs multi-criteria decision analysis (MCDA) to examine the techno-sustainability of four geothermal power systems: i) a business-as-usual geothermal power plant (GEObau), ii) repurpose two completely AOGWs for geothermal power generation (R-GEOdouble), iii) repurpose a single completely AOGW (R-GEOsingle), iv) repurpose semi-AOGWs (i.e., wells still in operation but with high water cut, R-GEOsemi). We assessed 30 criteria across technical, environmental, economic, and social dimensions via the analytical hierarchy process. The study identifies R-GEOsemi as the most techno-sustainable option due to its superior performance across environmental, economic, and social dimensions. However, GEObau closely follows R-GEOsemi, securing its position as the second-best option, marked by its outstanding technical proficiency and robust environmental and social performance. Conversely, R-GEOdouble and R-GEOsingle show limited techno-sustainability competitiveness. When sensitivity analyses are applied to the weighting factors, R-GEOsemi demonstrates resilience and remains as the best option in most cases. However, GEObau could outperform R-GEOsemi when the value of technical criteria is increased (weightings >0.255) or when the weightings for environmental or economic aspects decrease (weightings <0.236 and < 0.244 respectively). R-GEOdouble and R-GEOsingle only overtake GEObau when the economic aspect reaches a weighting of 0.659 or more. Despite R-GEOsemi being the most promising option, it faces challenges due to limited power generation capacity and the availability of wells approaching their end-of-lives. The findings underline the necessity for broader stakeholder input, inclusion of more technical and social criteria, and data-driven decision-making processes.