This project consists of a study to test the feasibility of retrieving coal bed methane (CBM) water
that has been re-injected into the Fort Union aquifer. This would involve a pilot well to evaluate the
subsurface geology to confirm the ability to store produced CBM water. If data indicates that
storage/retrieval is feasible, then the well would be completed as an observation well. A second
production/storage well and another observation well would then be completed. Substantial
monitoring is necessary during the pumping/injection process, which indicates the need for a second
Several CBM producers are currently injecting CBM water as a means of disposal of excess
produced water (DEQ currently has over 240 re-injection permits issued). Determining whether
storage of this water and later retrieval is cost effective is what is needed to decide if the city of
Gillette will move forward to take this project beyond the pilot study requested here.
Gillette had predicted a large increase in its population due to the recent CBM boom and proposed
power plants. Storage of water in aquifers that are already experiencing drawdown would help
Gillette in serving the needs of their growing population.
To prevent contamination of the aquifer, prior to injection, CBM water would be disinfected with a
small disinfection facility built at the site. Water samples will be monitored for conductivity, pH,
chlorine and sulfates. Other assurances are needed as well to insure that wellfield treatment
chemicals are not introduced into the aquifer in toxic quantities.
RECOMMENDED LEGISLATIVE ACTION:
The WWDC recommends the project be incorporated into the New Development Program at Level II
with an appropriation of $510,000.