Performance of a Geothermal System in Petroleum Fields of the Taranaki Region, New Zealand

Extracting energy from petroleum fields is an attractive topic for research. In the Taranaki region, some of the depleted oil and gas reservoirs are prospective candidates for low-temperature geothermal development. This is because the hydrocarbon wells produce a large amount of coproduced water at the surface. Therefore, we analyse one of the hydrocarbon fields encountering fractured reservoirs in the Taranaki region. We aim to estimate the production rate and well separations to sustain generation capacity from the field for 10 years. We used the Volsung reservoir simulator to simulate the reservoir models using the MINC (the Multiple INteracting Continua) formulations and representative rock properties. Then we analysed the behaviour of the petroleum reservoir over time with the extraction of geothermal energy. It was found that a flow rate of 180 kg/s is sufficient to produce 6 MW of electricity and could be sustained for at least 10 years. The work suggests that the theoretical maximum production rate between production and reinjection well separated by 500 m would be 220 kg/s before the production enthalpy declined below 20% of the initial value. But the field has several wells and larger separation between the production and injection wells. The model of the field has seen production rates of 180 kg/s to sustain a generation capacity of more than 6 MW without the evidence of any thermal breakthrough from the injection well over a period of 10 year. The model demonstrates the effective movement of the warmer fluids from the lower formations to the upper reservoir for higher production rates before the arrival of the cold waterfront from the reinjection well. For future analysis, it is recommended to conduct optimisation of the operation strategy in the field. A detailed thermo-economic study could also be performed to analyse the benefits of ultimate oil recovery, aquifer effect, and the onsite power demand.