Synergy Between Production Of Natural Gas & Warm Water: A Reservoir Modelling Exercise Assessing Recovery Factor Sensitivity

Abstract

The Netherlands evolves from a net natural gas exporter to being a net importer. With renewable energy in The Netherlands still not able to fully replace natural gas as an energy source, the Dutch security of energy supply is at risk. On local scale, especially for greenhouses, geothermal energy has proven to be a reliable replacement for natural gas as the primary heat provider. Yet with the ambition of the Dutch government to achieve a 49% CO2 emission reduction in 2030 of which partly is assigned to the realisation of geothermal heat production, the maturation of the geothermal potential is too low. One of the main causes for this low maturation rate is the financial risk attached to both the exploration and exploitation phases of a geothermal project. Synergy between hydrocarbon- and geothermal exploitation could improve the aforementioned security of supply and simultaneously reduce financial risks of geothermal projects. The positioning of a geothermal doublet in the water leg of a gas field (figure 1) potentially extends field life and subsequent earnings from natural gas-production which in turn can be invested in the aligned geothermal project(s). This poster presents the results of two case studies, examining synergy at the Roden and Boskoop gas fields, that demonstrates geothermal production close to the gas-water contact could delay water breakthrough in the gas well(s), potentially increasing the recovery factor. The magnitude of increase of the recovery factor predominantly depends on the amount of aquifer support. Synergy in a weak aquifer (Boskoop case study) has no significant impact on the recovery factor. However, the addition of an artificial strong aquifer resulted in a 20% increase in recovery factor. Synergy with a moderate aquifer (Roden case study) resulted in a 3.3% increase in recovery factor. Furthermore, although not as strongly, the magnitude of increase relies on positioning of the geothermal wells relative to gas producer(s), geothermal flow rate and potentially the permeability. The study also demonstrates that gas fields in a late stage of gas production could still benefit from the addition of geothermal doublets. It might be too late to achieve the full potential of synergy between gas- and geothermal production, but a modest increase in recovery factor can still be expected. The Roden case study showed that a 1.1% increase in recovery factor could be achieved with the instalment of a geothermal system at a late stage of gas production.

AAPG Datapages/Search and Discovery Article #90345 © 2018 AAPG European Region, Geothermal Cross Over Technology Workshop, Part II, Utrecht, The Netherlands, April 17-18, 2018