Saline aquifers and seals

Purpose

To develop multi-disciplinary methodology and workflows for i) evaluating the impact of CO2 on the aquifer system including saline water displacement; ii) estimating the CO2 seal capacity of fault and top seals; and iii) provide input to more accurately estimate storage capacity and containment security.

Summary

An integrated approach will be adopted to simultaneously investigate structural architecture, hydrodynamics, fault and top seal capacity, CO2 migration and saline water displacement. Integrated seals theory for CO2 will be evaluated in the context of a sub-basin scale study punctuated with detailed field-scale examples.

Natural analogues of high and low CO2 content hydrocarbon accumulations provide examples of containment and leakage at geological time scales. Examining the various seal characteristics of natural analogues provides calibration to seal capacity estimation methods. The complexity of most natural analogues requires a multidisciplinary approach for adequate characterisation. This includes an understanding of CO2 migration in hydrodynamic systems.

Based on data coverage, CO2 content, and trapping style, a basin will be selected to evaluate sub-basin scale trends in top and fault seal capacity. The described integrated approach will be taken to evaluate the hydrodynamics and aspects of seal capacity relative to the observed distribution of CO2. From the regional evaluation, several key case studies will be identified that will subsequently be characterised in detail. Detailed case studies will provide ground truthing of seal capacity estimation methods.

Lessons learned about the seal capacity to CO2 from the regional and detailed studies will be used to define a methodology and workflow for estimating CO2 seal capacity and risking containment security for proposed sequestration sites.