(Reuters) - Southern California Gas said on Wednesday it completed safety review tests at most wells at its Aliso Canyon natural gas storage facility in Los Angeles, which shut in October 2015 following a massive methane leak not plugged until February.
The utility, however, did not say when it would be ready to seek state regulatory approval to inject gas into the giant field.
Under state law, SoCalGas cannot inject fuel into the field until the California Division of Oil, Gas and Geothermal Resources (DOGGR) approves the company's testing of the 114 wells at the facility to ensure their safety.
SoCalGas is owned by California energy company Sempra Energy. Aliso Canyon is the biggest of its four storage fields. It supplies gas to homes and businesses in Southern California, including power plants and refineries.
DOGGR said on its web site that 28 wells at the facility have passed all safety tests, seven awaited test results and 79 were temporarily out of operation.
All wells must either pass all tests or be taken out of service before DOGGR can call a public meeting. Since DOGGR must give the public 15 days notice before a meeting, SoCalGas could not start injecting gas into Aliso Canyon until some time in November at the earliest.
In addition to DOGGR, the California Public Utilities Commission must also determine the field is safe to operate.
After the state allows the company to inject gas into the field, SoCalGas has said it will continue testing wells that were temporarily sealed in an effort to bring them back into service.
The state required SoCalGas to keep 15 billion cubic feet of gas in the 86-bcf facility to minimize the risk of gas shortages that could result in electricity outages.
The PUC in late September reduced the required minimum withdrawal capability SoCalGas must maintain from 420 million cubic feet per day to 207 mmcfd.
Separately, SoCalGas also said it replaced the inner tubing of all of the DOGGR approved wells, adding more than 40 miles of new steel piping.
In accordance with new regulations and state laws, withdrawal and injection of gas now will occur only through the newly installed inner tubing, the company said.
The casing around the inner tubing provides a secondary layer of protection against potential leaks. A federal task force this week called for a two-pipe system at all U.S. facilities.
Reporting by Scott DiSavino; Editing by Chizu Nomiyama and David Gregorio