Saline Aquifiers

Characterization of and Capacity Estimates for Saline Aquifers

A saline aquifer can refer to any one of a number of sedimentary rock types saturated with saline, non-potable water, from which the water can be drawn, and into which fluids can be injected (IEA, 2004). Aquitards are rock layers in which water can exist, but from which water cannot be produced, because the permeability is too low to allow water to flow at an acceptable rate. An aquiclude is a rock with almost zero permeability. All three of these formations play a role in deep CO2 injection, with aquifers providing the pore space for storage, and aquitards and aquicludes providing the physical trapping mechanisms.

Deep saline aquifers provide the greatest volumetric potential for storage anywhere in the world. Saline aquifers run deep under all 68 Canadian sedimentary basins, and provide access to storage opportunities in many parts of the country.

Deep basin mapping of saline aquifer geochemistry in the Western Canada Sedimentary Basin (WCSB)

Along with the Geological Survey, CanmetENERGY is involved in the mapping of saline aquifers in Canada. The objectives are to produce a series of 1:5 million scale maps of deep saline aquifers in the Western Canada Sedimentary Basin on a formation-by-formation basis. Individual maps will be produced for total salinity and major geochemical parameters.

Develop methodologies for estimating storage capacity in aquifers

This mapping activity will include the development of a methodology to assess the technical CO2 storage capacity of deep saline aquifers. The development of a standard methodology for estimating capacity is critical in selecting storage sites that are immediately available. The methodology is fundamental to industry in making investment decisions, to regulatory agencies in the permitting process, and to governments for policy making.

Not only can CO2 be stored in saline aquifers, as shown in the diagram, CO2 can be stored in the following geological media:

  • oil and gas reservoirs, either at depletion or for enhanced oil, and possibly gas, recovery;
  • uneconomic coalbeds, with the possibility of producing coalbed methane;
  • deep aquifers saturated with brackish water or brine; and
  • salt caverns