Estimation Of Parasitic Load For The Potential Geothermal Wells Of The Clarke Lake Field, British Columbia: A Case Study

Abstract

Alternative sources of energy must be explored in order to reduce the environmental footprint of the production and use of fossil fuels. Geothermal energy, a baseload renewable resource, has the potential to play a significant role in mitigating excessive greenhouse gas emissions into the atmosphere. Successful geothermal power development requires that significant attention is paid to decreasing parasitic losses, increasing power conversion efficiencies and reducing costs for related components. The parasitic load for a binary geothermal plant can reach as much as 20-30% although the target is to keep it close to 5%. Here, we present a workflow for calculating the parasitic load for prospective wells in a potential geothermal field. We then apply this workflow to the Clarke Lake Gas field in NE British Columbia as a case study. The Clarke Lake field in British Columba, Canada, hosted by middle Devonian carbonates of the Slave Point Formation has produced more than 1.6 Tcf of sweet gas since 1957. The combination of a thick, highly porous formation, and subsurface water temperatures in excess of 110 °C make the field one of the most promising areas for geothermal development in Western Canada. The Clarke Lake field has the capability of producing 12 to 72 MW of geothermal energy with a recovery factor of 0.1 to 0.25. Developers often ignore the pumping power required to elevate the fluid from a well to the surface, which may lead to an erroneous calculation of the net power and parasitic load. We estimate the pumping power from the calculated height of the water column in a well based on the maximum pressure of the reservoir and density of the fluids. For consistency and accuracy, we have only selected the wells that have undergone the drill stem test (DST). Out of 187 wells listed in, 37 wells have all the data required for our analyses. Our results show that almost half of these wells would require a minimal power > 0.1 MW to bring the fluid to the surface, thus making them attractive for geothermal production.

AAPG Datapages/Search and Discovery Article #90346 ©2019 AAPG European Region, 3rd Hydrocarbon Geothermal Cross Over Technology Workshop, Geneva, Switzerland, April 9-10, 2019