Storage Appraisal - Appendix A5.5 - Representative Structure Modelling of Aquifers with Identified Structure

Abstract:

This document is a supporting document to deliverable MS6.1 UK Storage Appraisal Final Report. This is Appendix A5.5: Representative Structure Modelling of Aquifers with Identified Structure.

The project did not seek to collect structural data on saline traps, but some data were available for dome structures in the Bunter form ation of the southern basin. As a result this storage type is the least numerous in the CarbonStore database, nonetheless its storage capacity is of particular interest, as such stores could combine the advantages of both open aquifers and pressure cells through structural containment with potentially less pressure restriction.

The storage capacity of the Bunter domes has been estimated previously on a volumetric basis, assuming a pore volume utilisation of 40%. The dynamic modelling work undertaken in this project improved these estimates byinvestigating pore volume utilisat ion and pressure interference between domes in a multi-injection scenario. The Bunter Formation was sub-divided into areal Zones and each of these Zones is classed as separate, but open, storage Units in CarbonStore. Zone 4 was selected for detailed study here as it contains the majority of the Bunter domes and so makes a significant contribution to the volumetric storage capacity in the Bunter domes.

The dynamic work on structural traps involved material balance Representative Structure modelling of CO₂ injection into all the Zone 4 domes described in this report and fine scale Exemplar modelling of injection into up to three selected neighbouring domes. Three versions of the Representative Structure model were constructed based on the minimum, most likely and maximum properties in CarbonStore. Most simulations assumed injectioninto all domes simultaneously. Injection was constrained by fracture pressure limits for each dome and the parent aquifer itself, set by data from CarbonStore. A rough optimisation of injection well numbers was performed as usually a point of diminishing added value was reached for additional wells.

Injection into a single dome to estimate the time required to fill the dome to the maximum assumed pore volume utilisation gave long filling times in excess of 100 years for large domes, despite using many wells. Injection into all domes simultaneously indicated significantpressure interference. Both these findings substantially reduced achievable storage capacities on likely project timescales, suggesting that these domes have achievable capacities substantially less than the maximum capacity indicated by the buoyant capacity limit

Publication Year:

2011

Publisher:

ETI

DOI:

https://doi.org/10.5286/ukerc.edc.000932

Author(s):

Masters, J.