Inventory and First Assessment of Oil and Gas Wells Conversion for Geothermal Heat Recovery in France

Abstract

The repurposing of oil and gas wells for geothermal energy production and resource assessment can provide sustainable solutions to meet the objectives of renewable energy balance targeted within 2030 by the French Parliament in the "energy transition law for a green growth" promulgated in August 2015. Approximately 12 000 wells have been drilled in France since the XIXth century for hydrocarbon reservoir exploration and exploitation. Most of them are closed and abandoned or nearing the end of production due to the planned end of exploitation of hydrocarbons in France by 2040. Several sustainable cases of conversion for geothermal energy production have been reported in France and abroad, demonstrating the possibility of using former wells for direct heat extraction from aquifers or in closed loop systems. This paper presents an overview of the wells drilled in France and the methodology proposed to identify and rank them according to the a priori feasibility of open loop conversion and power extraction from vertical heat exchangers. To this purpose, wells data, geological and hydrothermal information acquired by the BRGM (geometry and dynamic properties from models) and land occupation have been cross-referenced. The quantitative overview is followed by a detailed analysis of high profile wells to assess their conversion potential for geothermal energy production (possible use at surface, well drilling and abandonment reports, hydrodynamic properties of the reservoir, technology to be implemented, etc.). The study also looks at the regulatory framework associated with the abandonment of oil and gas wells and their conversion to geothermal wells.