On October 23, 2015 a massive natural gas leak was detected and subsequently demonstrated by infrared camera at the Aliso Canyon underground gas storage facility near the Porter Ranch section of Los Angeles, California. Over 2,000 residents have been relocated away from the leak and schools in the area have been closed as well. The leak has been estimated to be releasing 30-50 tons of methane per hour, and since October has released nearly 84,000 tons of methane.
Unfortunately, this leak isn’t going away quickly. Work crews with SoCal Gas have tried injecting a brine solution into the leaking well, but that did not stop the leak. Now the company is drilling a relief well (similar to what was done with the BP oil spill in the Gulf of Mexico). Once completed, workers will inject a plug approximately 8,500 feet below the surface. However, it may be February or even March before the leak is finally plugged.
The leaking well was drilled in 1954 as an oil well. After the oil and gas was depleted from the basin, the well and the subsequent underground cavity was converted in 1973 to an underground gas storage reservoir, one of nearly 400 underground storage facilities around the country. The well originally had a sub-surface shut-off valve. But in 1979, that was removed – ironically it was leaking – and not replaced as the facility is not a “critical well” under state law because it is more than 300 feet from any homes. If the valve had been in place and the leak was above the valve, it potentially could have shut off the well once the leak was detected, preventing most of the emissions.
However, no one is sure exactly where the leak is occurring. Some speculate that the leak is emanating from a break in the lining, or casing, of the well that is below where the shut off valve would have been located. If that is the case, the shut off valve would be of little use and good regulations on the proper casing of the well are what would be needed to prevent future Aliso Canyons.
The first priority going forward has to be the safety and health of the surrounding community and shutting down the leak. To protect the communities living around facilities like Aliso Canyon, we also need to look at what specifically caused the failure in this case, and strengthen regulations that could have prevented this catastrophe. After that, we need to harness the attention that this massive leak has garnered to reduce methane emissions throughout the oil and gas system. It’s important to remember that despite the massive size of this leak and the impact it has wrought on the surrounding community, the leak is a drop in the bucket when it comes to methane emissions from the oil and gas sector.
If the well continued leaking for an entire year, it could potentially release 350,000 tons of methane. Using a 20-year global warming potential (GWP), this is about 30 million metric tons (MMT) CO2e, or 7% of California’s GHG emissions. That is only about 5% of US Oil and Gas methane emissions. And again, that is if it goes on for a year. So while we must first and foremost plug this leak and fix any gaps in the regulatory structure that allowed this to happen, we have to continue pushing to reduce methane pollution throughout the oil and gas sector.
Currently, EPA does not have the authority to require any specific work practices for well construction, which would include the sub-surface safety valve, and any wellbore integrity standards affecting the casing of the well. In 1980, Congress amended the Safe Drinking Water Act, and included changes that removed EPA’s authority to address underground natural gas storage facilities. Additionally, it’s not clear that even a concerted leak detection program at the well surface would help because the monitoring would be taking place at or around the pipe; the emissions may not be visible there since the methane is moving up through the ground and may be released far from the actual well.
Recently, EPA and several states have begun a process to crack down on methane emissions. In 2012, EPA finalized standards targeting volatile organic compounds (VOC’s) from a number of sources within the oil and gas industry that will also reduced methane emissions, and then in August 2015, EPA proposed new methane standards for a much larger list of sources in production, transportation and storage of oil and natural gas.
However, EPA’s recent efforts on reducing pollution from the oil and gas sector have not touched the distribution sector, which is where the Aliso Canyon facility is located. This is the portion of the natural gas system which starts at the “city gates” where gas is metered, depressurized, and continues down into people’s homes. Leaks in the distribution system come from numerous places, including above ground systems, underground pipelines, and temporary underground storage facilities like Aliso Canyon. The U.S. GHG Inventory estimates that gas distribution systems emitted over 1,200,000 metric tons of methane in 2012. Emissions from distribution can be reduced in the near-term by finding and fixing leaks at large, above ground distribution facilities (such as metering stations and the facilities where gas is transferred from high-pressure transmission pipelines into low-pressure distribution systems). These measures could reduce emissions by at least 283,000 metric tons per year.
But the distribution sector is just one place that the EPA could target for additional reductions. Using proven technologies and relatively cheap practices, EPA could cut emissions from oil and gas nationally by 40-45%. This would be like switching off 8 or 9 continuous Aliso Canyon leaks.