Gippsland Basin Geosequestration: A Potential Solution for the Latrobe Valley Brown Coal Co2 Emissions

Abstract

Geosequestration of CO2 in the offshore Gippsland Basin is being investigated by the CO2CRC as a possible method for storing the very large volumes of CO2 emissions from the Latrobe Valley area. A storage capacity of about 50 million tonnes of CO2 per year for a 40-year injection period is required, which will necessitate several individual storage sites to be used both sequentially and simultaneously, but timed such that existing hydrocarbon assets are not compromised. Detailed characterisation focussed on the Kingfish Field area as the first site to be potentially used, in the anticipation that this oil field will be depleted within the period 2015–25. The potential injection targets are the interbedded sandstones, shales and coals of the Paleocene-Eocene upper Latrobe Group, regionally sealed by the Lakes Entrance Formation. The research identified several features to the offshore Gippsland Basin that make it particularly favourable for CO2 storage. These include: a complex stratigraphic architecture that provides baffles which slow vertical migration and increase residual gas trapping; non-reactive reservoir units that have high injectivity; a thin, suitably reactive, low permeability marginal reservoir just below the regional seal providing additional mineral trapping; several depleted oil fields that provide storage capacity coupled with a transient flow regime arising from production that enhances containment; and, long migration pathways beneath a competent regional seal. This study has shown that the Gippsland Basin has sufficient capacity to store very large volumes of CO2. It may provide a solution to the problem of substantially reducing greenhouse gas emissions from the use of new coal developments in the Latrobe Valley.

Hydrodynamic considerations for carbon storage design in actively producing petroleum provinces: An example from the Gippsland Basin, Australia

“…Although these effects are temporary, depending on the timing of CO 2 injection, these may have an impact on the direction and rate of CO 2 movement and/or the storage capacity of the various structures. Previous studies on the impact of these gradients on injected supercritical CO 2 suggest that initial containment may be enhanced within this stressed flow system (Underschultz, and Johnson, 2005;Gibson-Poole et al, 2006). The purpose of the current study is to further investigate the impact of production-induced gradients on the injected CO 2 and to demonstrate the importance of considering the formation water flow system in the overall injection strategy.…”

“…The assessment of the offshore Gippsland Basin identified several features that make it particularly favourable for long-term CO 2 storage: a) a complex stratigraphic architecture that provides baffles which slow vertical migration and increase residual gas trapping; b) non-reactive reservoir units that have high injectivity; c) a thin, suitably reactive, low-permeability marginal reservoir just below the regional seal to provide additional mineral trapping; d) long migration pathways beneath a competent regional seal to several depleted oil fields that provide storage capacity coupled with a stressed flow system (arising from hydrocarbon production) that may enhance containment (Gibson-Poole et al, 2006).…”

“…3). The injection scenario outlined in Gibson-Poole et al (2006) does not take into account the potential influence of the steep hydraulic gradients induced by production. These may impact the timing of injection, the eventual migration pathway and the short-term capacity at each individual site.…”

“…It is likely that the depletion and decommissioning of some of the major oil fields will coincide with the need for storage. Enhanced oil recovery is not being considered for the fields at this time, due to high primary recoveries (Gibson-Poole et al, 2006).…”

“…A detailed assessment of the suitability of the Latrobe Group sediments of the Gippsland Basin for geological storage of CO 2 has been carried out by CO2CRC and is described in Gibson-Poole et al (2006). A storage capacity of about 50 million tonnes of CO 2 per year for a 40-year injection period is anticipated (assuming 100% CO 2 emissions capture efficiency, thus representing the theoretical maximum storage capacity volume).…”