3 Storage technologies

The literature on carbon capture and storage discusses storage in saline formations, depleted oil and gas fields and coal seams (including enhanced methane recovery). It also discusses enhanced oil and gas recovery in conventional oil and gas reservoirs.

All the quantitative representative analyses in this report assume CO2 storage in a subsurface reservoir with a given set of reservoir properties. They assume supercritical or subcritical CO2 injection depending on the pressure regime of the transport and injection operation. The analyses implicitly assume injection sites with the reservoir properties assumed for the sedimentary basin where they are located.

The quantitative representative analyses of CO2 transport and storage presented in this report rely solely on indicative data on the reservoir properties of sedimentary basins in South-East Asia. These are based on geological assessments, seismic surveys and oil and gas exploration and production drilling. This generalised basin data is not sufficiently detailed to allow us to distinguish between specific types of storage reservoir into which CO2 might be injected.

Individual depleted or producing oil and gas fields are unlikely to have the same pressure regime as we assume applies to the sedimentary basin and we do not attempt to analyse depleted or producing fields in our representative cases.

We do not show quantitative analyses of CO2 injection for enhanced oil or gas recovery.

The ability to inject CO2 into the subsurface depends on many factors including the injection reservoir's permeability, porosity, areal extent, thickness, pressure and fracture pressure. The composition of the injected gas is also critical. In the representative analyses in this report, we assume that this is a mixture of CO2, methane and other hydrocarbons. The composition reflects the composition of the raw gas at the source.