Geothermal Adaptation of Abandoned Hydrocarbon Infrastructure - an Option for the Oil Industry to Extend Reservoir Utilization into the Area of Renewable Energy

Abstract

Hydrocarbon wells arc usually liquidated at the end of their life time but could be used instead for geothermal purposes, if potential heat consumers are at hand nearby. Common liquidation practice and retrofitting costs are rather contrary to the realization of such opportunities. In the future, by using inoperative but still not liquidated wells, chances may open up of extending the life time of some hydrocarbon fields by extracting renewable energy from existing wells. The feasibility of this approach, by using deep borehole heat exchanger technology, was tested for the area of the Vienna Basin, Austria, a major hydrocarbon source in Central Europe, on behalf of the Austrian oil company OMV. 270 wells were investigated. The results show that under local thermal and economic conditions it is difficult to achieve return of investment even on a long-term basis (30 yrs) for all but very few liquidated wells and for most wells currently still in service, too. This is especially true if a specialized company has to be contracted to operate the heat supply network. Given the prime cost for heal that network operators commonly accept (< 25 Euro/MWh) the thermal regime of the investigated area would have to be on the order of at least 160 mW/m2 of terrestrial heat flow density, corresponding to geothermal gradients of 70 to 80°C/km. In Europe at least there are very few areas where such conditions prevail. For future work, a software tool (Geothermal Planning Tool) developed for the project and integrating the complete set of necessary technical and economic parameters and calculations, shall be applied to other regions where conditions arc more favorable.