ANL will evaluate formation water withdrawn in association with CCS in a manner similar to that of produced water from oil and gas wells and develop possible uses and applications. In oil and gas exploration, produced water includes saline water found in underground formations that is brought to the surface in association with oil and gas extraction. For the purpose of geologic sequestration of CO2, production of water is not necessary in many cases, but may be withdrawn from formations receiving injected CO2 in an attempt to increase available pore space and alleviate overall formation pressure. Examples of management options for produced water include reinjecting the water into another formation (with or without treatment), treating and discharging the water to a surface water body, evaporating the water, or treating and reusing the water for some other beneficial purpose. A large number of promising geologic sequestration formations identified in the United States and Canada are deep saline formations in which formation water, if withdrawn in association with CCS, is likely to be quite salty, thereby limiting the options that can be selected without first treating the water.
To determine if formation water can be used for additional applications, ANL will investigate industries or sectors that may be able to beneficially reuse water that is of lesser or different quality than drinking water. Each of the possible applications will be evaluated to determine the water quality required supporting them, the treatment options necessary, and the costs associated with each. ANL will also conduct a qualitative investigation into innovative ways of using some of the components contained in formation water, such as heat (geothermal energy) and chemical constituents (lithium or other uncommon elements).
The U.S. Department of Energy’s (DOE) National Energy Technology Laboratory (NETL) is helping to develop technologies to capture, separate, and store carbon dioxide (CO2) to aid in reducing green-house gas (GHG) emissions without adversely influencing energy use or hindering economic growth. Carbon capture and sequestration (CCS) — the capture of CO2 from large point sources and subsequent injection into deep geologic formations for permanent storage — is one option that is receiving considerable attention.
Argonne National Laboratory (ANL), one of DOE’s oldest and largest national laboratories for science and engineering research, contends that by withdrawing water already residing in the receiving geological formations, the pressure caused by injection could be reduced and additional pore space freed up to sequester CO2. However, the produced formation water is typically of low quality (typically due to elevated total dissolved solids [TDS] concentrations) and must be handled and disposed of with care to prevent adversely affecting surface and groundwater resources. Nevertheless, there is potential for beneficial use of produced water from CO2 sequestration operations. NETL is providing funding to ANL to assess the available options for managing the water extracted from geologic formations receiving CO2 for storage purposes, including applications for beneficial use of the water.
NETL and the entire CCS stakeholder community will benefit from coordinated and focused information on where the formation water should be extracted, at what point in the sequestration process the water should be extracted, and possible applications for the water withdrawn from the formation. Some industries and industrial processes may benefit from the availability of CCS produced water in their regions,. Produced water may also have applications for geothermal power generation, as recent technological advances have lowered the minimum required temperature of geothermal fluids. Agriculture and livestock production may also benefit from the availability of produced water (particularly in arid regions) as the water quality requirements for crops and livestock are typically less than those for human consumption.
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