Refitting oil wells for geothermal uses

Mature oil fields are characterised by a large amount of co-produced water. Production costs become highly influenced by oil dewatering and water injection operations. Often, the produced fluids have a temperature higher than the ambient one. In order to compensate operational expenditure (OPEX) increase, the heat recovery from the produced stream could be quite interesting. The present study analyses different implementation scenarios of geothermal uses of future abandoned wells. Scenarios assume to implement the possible solution during the oil production field life up to its complete conversion to a fully geothermal field. Three different scenarios considering the possible use of hot stream from the wells have been studied. A first scenario concern the direct use in district heating; a second option of exploitation is in electric power generation through an organic Rankine cycle (ORC) plant; finally, a possible cogeneration scheme of electric power and heat have been assumed. The comparison of the different scenarios highlight an optimal configuration of the exploitation of the field, a combination of cogeneration and district heating. The choice to operate in cogeneration, in fact, allows to maximize overall system efficiency, reducing heat loss. The produced heat and electricity will be supplied to the nearby community, through a district heating network, extending the service to a large number of buildings. In the present energy outlook, the extension of the life cycle of an oil filed through its conversion to a geothermal field is a fundamental step. Considering the large number of oil wells that are abandoned every year around the world and could potentially be exploited to produce energy again it become a need.