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Western Part of Basin
Glamorgan-1 is the deepest of only a few wells drilled into the western Clarence–Moreton Basin.
The well intersected five metres of sandstone at a depth of 875 m (KB). Tuff fragments within the
sandstone indicate a high potential for reactivity with a CO 2 fluid (i.e. they are prone to diagenetic
alteration, which reduces injectivity). The area has high reservoir risk and negligible potential
storage volume. Reservoir quality does improve to the west (Thompson, 1987) and into the
adjoining Surat Basin. However, these potential reservoirs are relied upon heavily to supply
substantial quantities of ground water for irrigation and therefore cannot be used for CO 2 storage.
Southern Highlands Queensland
In this basin conventional gas was intersected at a depth of only 580 m, where the coal rank is low.
Russell (1994) suggested the source of the gas was thermogenic migrating from a mature deeper
source. This implies vertical migration and minimal long term sealing potential in the deeper
section. In addition, sample analysis shows the porosity of the main reservoir interval to be less than
7% (Thompson, 1987). As mentioned above, low porosity and permeability reservoirs are still being
evaluated for their potential as CO 2 storage sites.
New South Wales
Petroleum exploration to date (12 wells) has targeted various intervals and has failed to prove even
very small hydrocarbon volume potential (< 30 BCF). Sandstones in this part of the Clarence–
Moreton Basin are very lithic and the fluvial depositional environment indicates high potential for
laterally discontinuous seals (i.e. likely upward migration). Reservoir analysis estimates porosities
of less than five percent and permeabilities of less than 10 mD. The sandstone generally has a high
lithic content, including feldspars, carbonates, chert and volcanics. Some of the best porosity
measurements originate from the Walloon Coal Measures sandstones which have a clay dominated
matrix and no overlying sealing unit.
Clarence–Moreton Basin – Summary
The present dataset is not extensive enough for a detailed CO 2 storage assessment of the basin,
however the data that does exist suggests that overall the Clarence–Moreton Basin has a high
reservoir risk with unproven to leaky seals. The Ma Ma Creek seal, considered the most reliable
(O’Brien et al., 1994), has internal lithologies from which a reading of 11.2% porosity was
measured (Thompson, 1987). This reading exceeds the porosity of most sandstone reservoirs in the
Clarence–Moreton Basin.
The GEODISC project stated the Clarence-Moreton Basin has good potential to hydrodynamically
sequester large volumes of CO 2 within the Ripley Road Sandstone (Southern Highlands Queensland
and New South Wales, Bradshaw et al., 2003). However reservoir quality of sandstones in this basin
is generally poor, but erratic and leaky faults pose a significant containment risk – highlighted by
the discovery of gas in fractured basalts at a depth of 580m.
3.1.5. Nambour Basin.
The Nambour Basin shown in figure 3.1 has little potential for CO 2 storage because of the shallow
depth and absence of suitable seals. The basin is poorly explored, with a total sediment thickness
of approximately 500 m (Day et al., 1983). Storage volume would be comparatively low with
comparatively high risk as the CO 2 would be stored at sub-critical temperatures and pressures
without a regional seal to prevent vertical migration. The Nambour, Moreton and Maryborough
basins were interconnected during the Early Jurassic (Day et al., 1983) suggesting that a sequence
stratigraphic model incorporating data from all three basins may possibly indicate areas useful for
niche CO 2 storage opportunities. “The Nambour Basin has no potential to sequester CO 2 from either
major or minor sources” (Bradshaw et al., 2003).
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