Storage images


	Geological storage options for CO2. Several types of rock formations are suitable for CO2 storage, including depleted oil and gas fields, deep saline formations and deep, unmineable coal seams. Other types of formations such as basalts and oil shales are being examined by scientists for possible future use.		Aquifer trapping.
	Rock formations for geologic storage, such as deep saline formations, would be much deeper than any usable groundwater and separated from that groundwater by thick barriers of impervious rock. These formations generally already proved their effectiveness by keeping highly-salty saline water separate from usable groundwater for millions of years.		Fault trapping.
	Stratigraphic trapping.		Unconformity trapping.
	Facies change trapping.		As time goes on, increasingly secure trapping mechanisms come into play and the overall security of storage increases.
	CO2 will be injected at depths below 0.8 km (2600 feet ). CO2 increases in density with depth and becomes a supercritical fluid below 0.8 km. Supercritical fluids take up much less space, as shown in this figure, and diffuse better than either gases or ordinary liquids through the tiny pore spaces in storage rocks. The blue numbers in this figure show the volume of CO2 at each depth compared to a volume of 100 at the surface.		CO2 will be trapped as a supercritical fluid in tiny pore spaces in the storage rock, as is shown by the blue spaces between the white grains of quartz in this photograph of a microscopic section of storage sandstone.
	Porosity versus permeability.		Seismic imaging uses reflected sound waves to create pictures of underground rock formations. Pictures such as this show potential CO2 reservoirs and seal rocks as well as other geologic features such as faults. After injection begins, these pictures can show the location of the CO2. This picture also shows where two test wells were drilled to make measurements and take rock samples. Taken together, all this information can provide an accurate and detailed understanding of conditions underground.
	Drop hammer mounted on an excavator, to create seismic shockwaves used in seismic monitoring.		Rock samples are taken by drilling into potential storage sites. These samples show the types of rocks in the formations identified by seismic imaging and they enable the properties of those rocks that affect storage to be evaluated.
	CO2CRC researchers are conducting a number of regional studies to determine suitable locations for deep underground storage of CO2.		Mr Nasser Keshavarz of CO2CRC / Curtin University of technology using a large pressure vessel to simulate CO2 behaviour in the subsurface.
	Photomicrographs are one of the many techniques used by researchers to identify minerals and the fine structure in rock formations.		Photomicrographs are one of the many techniques used by researchers to identify minerals and the fine structure in rock formations.
	Porosity: a measure of how much pore space is between the rock grains.		Permeability: a measure of how well the pore spaces are connected by pathways.
	Suitable storage rocks: good porosity and permeability at a depth of more than 800m, overlain by a cap rock (seal) with low permeability.