California authorities last Friday filed the report of their latest accelerated review of oil/natural gas industry underground injection control (UIC) wells with the U.S. Environmental Protection Agency (EPA). There are more than 50,000 of the wells statewide.

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 (EOR) operations, state officials said. 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.

The report from the state Department of Conservation's Division of Oil, Gas and Geothermal Resources (DOGGR) division and the Water Resources Control Board focused on 532 UIC wells that were identified as injecting into federally protected groundwater, which has resulted in 23 wells being ordered shut (see Shale Daily, March 5). The water board is seeking more information on 155 other wells. No cases of drinking water contamination have been found.

“Continued vigilance [and ongoing investigative work] and testing will be needed, but so far we haven't found a significant risk to water supplies," said Steven Bohlen, the state oil/gas supervisor heading DOGGR, during a conference call with news media Monday. Jack Borkovich, head of the state water board's groundwater monitoring programs, joined Bohlen in answering questions.

The effort has been focused on UIC wells that were injecting into reservoirs that had not been exempted by EPA from the federal Safe Drinking Water Act. None of the injections were into existing drinking water supplies, but some of them went into supplies that could be made potable with treatment. The vast majority inject back into oil-contaminated waters, but they could be near drinking water reservoirs.

Closed injection wells will remain shut indefinitely until there is an exemption for the reservoirs in which they are injecting, and after operators obtain new operating permits, Bohlen said. "The permits have been rescinded, and this is the initial part of a broader review and other wells now on notice (155 of them) will be ordered closed on Oct. 15 if there is still no exemption for their reservoirs from EPA.

"The emergency rulemaking that the state has put in place is specifically for that purpose," he said (see Daily GPI, April 24).

When asked if there is any drinking water at risk from the oil/gas activities, Borkovich said that is still to be determined after further data is collected from the 155 wells under state scrutiny.

"We really don't know yet," he said. "The data that we have collected so far indicated for those wells on which data was sampled there is no connection between the injection activity and the water collected, but we're still waiting for additional information from operators at this point."

Bohlen and DOGGR have been the targets of increasing criticism from state lawmakers, environmentalists and the news media for allegedly being too lax in their regulation of the oil and gas industry (see Shale Daily, May 8).

A related issue has emerged surrounding cyclic steam injection wells that support much of the EOR production in the state. Recently, state legislative members have alleged that some 3,600 cyclic steam wells are not properly permitted, but Bohlen refuted that and said DOGGR has communicated with elected officials on the issue to correct their mistaken information.