Aquifer Brine - Initial Technical Analysis of Exemplar CCS Stores

Abstract:

This £200,000 nine-month long project, studied the impact of removing brine from undersea stores that could, in future, be used to store captured carbon dioxide. It was carried out by Heriot-Watt University, a founder member of the Scottish Carbon Capture & Storage (SCCS) research partnership, and Element Energy. T2 Petroleum Technology and Durham University also participated in the project. It built on earlier CCS research work and helped develop understanding of potential CO₂ stores, such as depleted oil and gas reservoirs or saline aquifers, located beneath UK waters. It also helped to build confidence among future operators and investors for their operation. Reducing costs and minimising risks is crucial if CCS is to play a long-term role in decarbonising the UK’s future energy system.

This report aims to address whether or not there is potential to significantly increase CO₂ storage capacity, and thereby reduce overall cost of storage, by producing brine through dedicated production wells from target storage formations. Brine production is proposed as a method to manage pressure in storage sites, as a corollary to water injection during hydrocarbon extraction. In the case of CO₂ storage, the production of water creates voidage to increase storage capacity and reduce the extent of pressure increase due to CO₂ injection, and hence reduce the risk of caprock failure, fault reactivation and induced seismicity; additionally, it reduces the energy available to drive fluids through legacy well paths and other potential seep features. Spatially the reduction in the extent of the pressure plume reduces the affected area which can reduce the area of potential drilling interference, the number of impacted legacy wells, and the area of investigation for monitoring where brine movement is a concern. In this report five systems are considered: the Forties Aquifer, the Bunter Aquifer, the depleted Hamilton gas field, a producing North Sea oil field, and a synthetic tilted aquifer. The well counts, the period and the rate of brine production are data that are supplied for economic analysis to determine whether or not the process is a viable means of increasing storage capacity and reducing overall costs

Publication Year:

2016

Publisher:

ETI

DOI:

https://doi.org/10.5286/UKERC.EDC.000072

Author(s):

Jin, M., Olden, P., Pickup, G. and Mackay, E.