The Search for Sites for Geological Sequestration of Co2 in Australia: A Progress Report on Geodisc

Abstract

The APCRC GEODISC research program has encountered many challenges looking for geological sequestration sites for CO2, but has also found some solutions. Challenges already faced have been in effectively searching databases, developing uniform terminology and evaluation methodology, establishing comparative quality assessment of Australia’s sequestration sites against each other and against those from overseas, improving our understanding of the injection and trapping properties of CO2 and predicting its effects on reservoirs/seals, and developing economic and reservoir models.Pilot research projects at the regional and site specific levels have been used to address these issues, as well as developing generic models, before building site specific models. Issues such as storage efficiency and the use of carbonates as CO2 sequesrationt reain challenges for the future.Preliminary conclusions reached from the regional study of Australia suggest that suitable deep saline formations will be widespread, have the largest sequestration volumes, and are likely to be the most economically attractive option currently available. In the future, some depleted oil and gas fields and enhanced coalbed methane production sites may also represent local high-volume options. It is considered unlikely that sequestration into voids/cavities or associated with enhanced oil recovery (EOR) will represent attractive options other than in exceptional circumstances. Despite these limitations, it is expected that many of Australia’s sedimentary basins will have excellent sequestration sites. The GEODISC program will provide an assessment of the critical factors required for success at each site.Several of the highest-ranking saline formations are currently undergoing site-specific study. Early indications are that the petrophysical data required for models of injection, migration, and trapping is of limited availability. Various methods are required to estimate the distribution and likely variability of these parameters across any site.These and other uncertainties in the distribution, quantity and quality of data required for predictive modelling necessitate an innovative and thorough approach to handling both risk and uncertainty. This will also be a challenge to be addressed during the GEODISC program.From the GEODISC work to date, it appears that it will be technically feasible to sequester large quantities of CO2 in geological formations in Australia for long periods of time. What is less clear is whether this can be done at a cost that would not impose an unreasonable economic burden on Australian industry. The future results for GEODISC will be highly relevant to answering this key question.

A procedure for determining the preliminary maximum injection pressure for CO2 sequestration

“…However, high injection pressure generates new fractures or reactivates existing faults in the rock mass, causing seismic activities. Supercritical CO 2 then leaks out along the new fractures and the reservoir seal is reduced, as shown by earlier studies (Rigg et al 2001;Sminchak et al 2002). Possible damage to the cap rocks caused by excessive CO 2 injection pressure could also lead to leakage.…”

Regional study on potential CO2 geosequestration in the Collie Basin and the Southern Perth Basin of Western Australia

“…Are there viable natural resources at the site that may be compromised, e.g. proven petroleum system, groundwater, coal or other natural resource Bradshaw et al, 2002;Rigg et al, 2001)?…”

Effects of different fluids on microcrack propagation in sandstone under true triaxial loading conditions

“…Research studies on the action of rock mechanics with pore fluid are gradually becoming problems of interest in the field of geotechnical engineering. The injection of artificial fluid into deep strata changes the pore pressure and fluid components and may lead to surface uplift, caprock rupture, and fault activation and induce earthquakes . For example, In Salah CO 2 geological sequestration project, the surface bulged upward at an average rate of 5 mm per year, causing the project to be halted temporarily .…”