California oil/natural gas regulators last Wednesday outlined more details of the state underground injection control (UIC) program in a submittal to the U.S. Environmental Protection Agency (EPA). This marks the second of many milestones the state is committed to under a 24-month review of the UIC program (see Shale Daily, June 1).
The state Department of Conservation (DOC) and its Division of Oil, Gas and Geothermal Resources (DOGGR) offered further detail on the fate of 11 aquifers in which UIC wells may have to be shut in.
Earlier this year, DOGGR regulators moved to close 12 oil and gas UIC wells in Kern County and began stepped-up review of others to ensure that the state’s drinking water is protected from contamination (see Shale Daily, March 5).
DOGGR's latest update for EPA covers three areas:
A preliminary assessment of whether 11 aquifers historically treated as exempt from the Safe Drinking Water Act (SDWA) presently meet the criteria for an aquifer exemption and more details on the phase-out of injection wells in aquifers that may not qualify.
Details of a plan for public participation if and when aquifer exemption proposals are submitted to EPA, including public hearings in the areas where exemptions are being sought.
A detailed plan to strengthen the state’s UIC program through rulemakings, project reviews, and the development of a new data management system.
DOGGR said one of the 11 aquifers has too high a concentration of total dissolved solids (TDS) to qualify under the SDWA, so no further work is required. On the rest of them, most or all may not meet the criteria for an aquifer exemption.
Under the interim regulations established by DOC last April (see Shale Daily, April 24), a schedule has been set in which to eliminate all injections into what are deemed by the federal government to be "nonexempt" aquifers and to make sure all of the oil/gas activities in the state comply to the SDWA.
Injections into any nonexempt aquifers with water quality less than 10,000 TDS must be halted by Feb. 15, 2017, and in the interim, injection into 11 other specific aquifers must be ended by the end of 2016. Other injections into nonexempt aquifers that don't contain oil reservoirs and specified water quality (3,000 TDS) must be ended by Oct. 15, 2015 or sooner.
The SDWA does not apply to water with TDS greater than 10,000 TDS, and that injection can continue if the state applies for and receives an aquifer exemption from the U.S. EPA.
Currently available information indicates that the bulk of the aquifers contain between 400 and 3,325 milligrams/liter of TDS, and are found at depths as shallow as 200 feet and no deeper than 3,000 feet. "However, there are residual water quality questions to be resolved concerning these aquifers that may support exemptions, and we are continuing to work with operators to resolve data gaps," said Steve Bohlen, oil/gas supervisor heading DOGGR.
The oil/gas regulators further differentiated the aquifers by those still operating UIC wells and those that have ceased that activity.
"Five of the 11 aquifers appear to have no wells actively injecting. DOGGR believes it is unlikely that any operator will endeavor to collect and present new information regarding those aquifers," Bohlen said. "[DOGGR] will likely conclude its evaluation of those aquifers sooner than it will for the aquifers in which injection is occurring. We will continue to be in regular communication and provide [U.S. EPA] with updates on our progress as we go."
There are more than 50,000 of the UIC wells statewide, and so far the crack down on their oversight has not impacted the state's overall production, DOGGR indicated in an earlier filing to U.S. EPA (see Shale Daily, May 19).
About three-quarters of the state's oil production is dependent on these wells because the vast majority of them are part of enhanced oil recovery operations, state officials have told EPA. These are injections into oil-bearing formations to produce more oil. Some 1,800 of the UIC wells inject into formations that don't produce hydrocarbons.