Fracking fluid is typically more than 99 percent water and sand, with small amounts of additives used to control the chemical and mechanical properties of the water and sand mixture. In Colorado, much of the fluids used in the fracturing process are recycled and are not sent to wastewater treatment plants. Waste water disposal is always a concern and great care is taken to recover and control fracturing fluid and produced water. About 60 percent of the fluids that are disposed of go into deep and closely-regulated waste injection wells, 20 percent evaporates from lined pits and 20 percent is discharged as usable surface water under permits from the Colorado Water Quality Control Commission. Procedures for individual wells vary according to reservoir characteristics and the economics of the particular well. Costs of a specific procedure are always weighed against the results achieved. BLM Colorado tracks these procedures on Federal wells under its overview.
Operators must submit also Applications for Permit to Drill (APDs) to the agency. As part of the APD process, a BLM Colorado geologist identifies potential subsurface formations that will be penetrated by the wellbore. This includes all groundwater aquifers and any zones that would present potential safety or health risks that may need special protection measures during drilling, or that may require specific protective well construction measures.
Once the geologic analysis is completed, the BLM reviews the company’s proposed casing and cementing programs to ensure the well construction design is adequate to protect the surface and subsurface environment, including the potential risks identified by the geologist and all known or anticipated zones with potential risks.
The BLM conducts inspections throughout the drilling phase, and conducts site visits during the casing and cementing of the groundwater-protective surface casing and other critical casing and cementing intervals. The BLM reviews the well design before hydraulic fracturing takes place. Depending on the well design requirements, surface casing and some deeper, intermediate zones are required to be cemented from the bottom of the cased hole to the surface. The cemented well is pressure tested to ensure there are no leaks and a cement bond log is can be used to ensure the cement has bonded to the casing and the formation. BLM requires submission and approval of a Sundry Notice for “non-routine” fracturing jobs and a subsequent report detailing the results of the operation. The BLM may be onsite during those operations as well as when abnormal conditions develop during the drilling or completion of a well.
Nationally, the BLM is also working on rules to require companies to publicly disclose the chemicals used in hydraulic fracturing operations on public and Indian lands. The final release of those rules is still pending. For more information, visit: www.blm.gov/wo/st/en/info/newsroom/2012/may/NR_05_04_2012.html or www.blm.gov/wo/st/en/prog/energy/oil_and_gas.html