Axis recently completed a dynamic modelling study for a CCS developer in Australia
The study evaluated the storage potential and screened development concepts for a saline aquifer within composite confining system geology. It examined a large vertical interval of fluvial-deltaic origin, comprising highly heterolithic sand and shale sediments without a continuous conventional seal.
Shaun Bambridge (Principal Reservoir Engineer, Axis) commented: “This work demonstrates the feasibility of commercial scale storage in somewhat unconventional CCS geology and supports opportunities in similar systems elsewhere. It confirms the secure storage of CO2 and indicates that containment is robust to subsurface uncertainty despite the absence of an extensive seal in open aquifer. Store performance, quantified in terms of rate and capacity, is predominantly governed by the controls on injectivity in this system, which represent the key risks requiring further appraisal.”
The study also devised a novel approach to leak modelling in overburden through reservoir simulation. The approach captured leak dynamics over thousands of years and enabled estimates of terminal leak volumes, plume extent and the long-term fate of CO2. This will further support rock physics analysis to understand detection feasibility and inform the site MMV.
Shaun added: “The dynamic model tested alternative cases for geological and legacy well vertical migration involving a range of assumptions. This included assessing leak rate decline, duration and the potential loss of containment, which are in proportion to the store capacity and leak depth (or hydrostatic potential). In some cases, results could plausibly amount to migration of material volumes of CO2 over the long term. In this particular study, leaks are highly unlikely and the geology offers strong secondary containment qualities meaning that the overall risk to sensitive environmental receptors is low.”
NOTE: Client and site details withheld due to confidentiality.
