Feasibility of repurposing existing and abandoned hydrocarbon wells in the form of a geothermal well-triplet system

Abstract

There are various types of extraction and utilization possibilities of geothermal energy, of which a large group is energy recovery. The development of this sector is slow mainly due to its high initial investment demand and the long planning phase. The overall goal of the present research is cutting the cost of the drilling phase as the most expensive part of the establishment by repurposing unused and abandoned hydrocarbon wells. The article assesses the feasibility of a geothermal well-triplet system chosen to be the most promising technique amongst several utilization possibilities depending on the characteristics of both the geological media and the method itself. From the 14 examined abandoned wells three were found to be suitable based on their current condition and distance from each other. The mentioned technique requires an adequately porous and permeable media which was not provided by the initial depth of the wells, thus the considerable option left was to overdrill the existing wells till they reach the target geology, the known fractured karstic aquifer below. The current study summarizes the final results of a long going research, from the geographical-, lithological surveys till the potential heat-transport modeling. This article supports the final aspirations of a further going research project as an integral part of it carried out by the University of Miskolc.