Now that Southern California Gas Company has plugged the natural gas well that polluted air around Porter Ranch for months, the utility must address the problem that caused the leak in the first place: it has dozens of wells that are even older than the 63-year-old well that failed – wells that in many cases are long overdue for maintenance.

The leak at the Aliso Canyon gas storage facility spewed about 5.4 billion cubic feet of methane, a potent greenhouse gas into the atmosphere with trace amounts of other chemicals, according to a State Air Resources Board estimate.

Some have called the leak the nation's worst-ever methane leak. As bad as it was, the leak might have been expected given the warnings from SoCal Gas that its vast inventory of wells in the region is, on average, 52 years old and is becoming ever-more difficult and costly to repair.

"Regrettably, there is a broader theme than Aliso Canyon, that we have a lot of very old infrastructure in energy that we have to address for the 21st Century," said U.S. Energy Secretary Ernie Moniz during his mid-February visit to the leak site. He called for stronger monitoring and control of methane leaks.

"Frankly, gas storage fields need a fresh look in terms of some of the regulatory requirements. That was clearly brought home here."

Only weeks before the Oct. 23 leak was discovered, the state Department of Conservation criticized a subordinate agency, the Division of Oil, Gas and Geothermal Resources (DOGGR), which oversees operations at gas fields like Aliso Canyon. In a report, the department said DOGGR was understaffed, undertrained, poorly-led and plagued with outdated recordkeeping, data and regulations. A plan to make over the division is still in draft form, but some elements of it — like more intensive inspections — have been accelerated in the wake of the gas leak.

"I'm sure if they could have a do-over, they would have configured that well differently," said Paul Bommer, a senior lecturer in petroleum engineering at University of Texas at Austin. He called the leak at Aliso Canyon gas field "a preventable deal."

Old wells, urgently in need of repair

Of 198 active gas wells owned by SoCal Gas, 75 were drilled in the 1950s or earlier. There may be even more aged wells because another 37 have no initial drill date listed in the sometimes incomplete public records at DOGGR.

In a 2014 regulatory quest for higher gas rates, the company told the California Public Utilities Commission that is had to renovate 36 wells because of leaks or problems with safety valves between 2008 and 2013. The company proposed a six-year program of intensive inspections that would help it target which wells most urgently need repair. The CPUC has not yet ruled on the request.

The well near Porter Ranch that ruptured is known as Standard Sesnon 25. It was first drilled in 1953 in what was then an oil field in Aliso Canyon in foothills of the Santa Susanna Mountains at the north end of the San Fernando Valley.

Like Standard Sesnon 25, most of the active gas wells SoCal Gas operates started out as oil production wells that were later converted to gas storage wells. They are used to inject and withdraw natural gas in and out of rock formations thousands of feet underground.



"Without a robust program to inspect underground storage wells to identify potential safety and/or integrity issues, problems may remain undetected," the SoCal Gas rate request document said, noting that many of its wells are close to homes, and its underground storage fields extend underneath homes.

Age distribution of SoCal Gas storage wells Southern California Gas Co. filing with CPUC

So how did SoGal Gas get to the point of losing control of an aging well in its largest, most important gas field?

The practice of storing gas underground in Southern California began as a government wartime project in Playa del Rey.

Playa del Rey: Some wells date to 1930s

The Playa del Rey gas storage field located near the Ballona Wetlands between Marina del Rey and LAX has 29 active gas wells, including eight that were drilled in the 1930s. It is the smallest of the SoCal Gas storage fields, with 2.6 billion cubic feet of gas stored underground. The reservoir stretches under nearby homes, the Ballona Wetlands and part of the Marina del Rey boat harbor.

Oil prospectors swarmed Playa del Rey in the 1920s, drilling plenty of dry holes. The first big well was discovered in 1929. Those oldest oil leases registered names with the state like "Happy Days" and "Recreation Gun Club." One well that would eventually be converted to a gas storage well was named "King Vidor" apparently after the famous director and founder of the Directors Guild of America. Eight wells at the Playa del Rey field, drilled between 1935 and 1936, remain active today as gas storage wells, according to DOGGR records.

A 1931 report from the state Division of Oil and Gas about the discovery of oil at Playa del Rey. CA Division of Oil and Gas

The oil ran out by the 1940s. The field was taken over by the federal government in 1942 and converted to a natural gas storage field to serve the war effort. Post-war, it was transferred to the federal Reconstruction Finance Corporation and sold as surplus to Southern California Gas Co. in 1953.

Over the next few years, SoCal Gas built out the field and injected 27 billion cubic feet of gas in the field as "cushion gas," that is, the amount of gas that remains underground to keep the reservoir's pressure high enough that additional gas can be moved in and out. Some of the wells are directionally drilled so that the underground gas field extends well beyond the limits of the SoCal Gas property footprint.

The Playa field has had at least 10 leaking wells over the years, including several wells that were repaired, then leaked again, according to a CPUC document concerning the sale of surplus SoCal Gas property at Playa del Rey.

It said some gas that was stored underground has escaped to the surface over the years through cracked well casings or from old wells that were plugged by their original owners, not SoCal Gas. Some were plugged with insecure methods like shoving old telephone poles down the hole and topping it with cement.

The leaking well at the Aliso Canyon gas field was more than a mile from homes at Porter Ranch. State regulations permit gas storage wells to be 300 or more feet of homes. Any closer to homes, roads, parks or populated places, it's considered a "critical well," and stricter rules apply.

Operators of the gas storage project at Playa del Rey appeared to be very aware of that 300-foot buffer. In 1984, the company submitted a surveyor's map showing that a home was just far enough away from a well called "Pomoc 1" to avoid that "critical" label. It was outside the 300-foot limit by 45.6 inches. SoCal Gas got state regulators to "reclassify the well as non-critical."

A well that was a bit farther than 300 feet from a home is deemed non-critical and spared stricter operating rules for wells that are closer to homes. SoCalGas filing with state Division of Oil, Gas and Geothermal Resources

When an emergency shutdown valve in the field malfunctioned in 2003, a fine oil mist covered some nearby homes. SoCal Gas paid to clean homes, cars and yards.

In December 2007 the company settled a complaint by the CPUC over odors coming from the Playa field. The settlement required SoCal Gas to minimize its venting of natural gas, to capture some of the vapors coming from the plant and conform to the South Coast Air Quality District's requirements. It also had to monitor the area for gas coming up in the soil from abandoned or closed wells, and check for ground subsidence due to the withdrawal of oil or gas.



Another concern with the Playa field was gas migration. Underground gas stores can move through cracks in the earth and other vents to the surface where they escape into the air. Or it can collect under a structure and become an explosive hazard. That's what happened in 1985 when the Ross Department Store exploded at Third and Ogden streets in Los Angeles.

Environmentalists have been using the issues at the storage field for years in their efforts to put further restrictions on the site.

The nonprofit Environmental Law Foundation sued SoCal Gas in 2007, claiming that it violated California's Prop 65 anti-pollution law by injecting too much gas underground at Playa del Rey, causing the gas to contaminate the city's drinking water. That case settled in 2012, with the company paying nearly $1 million and agreeing to increased gas leak monitoring, said foundation attorney Jim Wheaton.

The most visible problem in recent years was the explosion of a vent stack at the gas field on Jan. 6, 2013. The flare could be seen for miles. SoCal Gas blamed operator error, but Councilman Bill Rosendahl said he questioned "whether the surrounding area will be safe if another incident occurs."

Roy Bagdasarian's home on Veragua Drive is on a bluff with a spectacular view of the ocean, Ballona Creek, Marina del Rey, and, below, the gas field's pipes, tanks and wells. He's lived there 28 years and describes the company as a good neighbor.

"We've never had a problem with these guys," Bagdasarian said. "I can smell gas two-three times a year, goes away very quickly and they've been good neighbors to me."

He was not at home during the explosion, but heard about it from neighbors.

"It was a big old fire plume that went 30, 40, 50 feet in the air and then it was done," Bagdasarian said.

SoCal Gas paid to clean several houses whose owners claimed damages, but Bagdasarian's was not among them, he said.

He stressed that he knew the gas field was nearby when he moved to the area, and the Porter Ranch incident reassured him that if something at Playa del Rey were to go wrong, the gas company would relocate him until it was fixed.

In August 2015, DOGGR notified SoCal Gas that 19 of its wells (including "Pomoc 1," the well that was close to a home) had not demonstrated "mechanical integrity" and were overdue for pressure tests used to detect if leaks are present. One of those wells, called Vidor 7, was tested later in the month and failed because of leaking valves at the wellhead. The company received a notice of violation in November. DOGGR spokeswoman Theresa Schilling said in an email that the company had received an extension of time to perform the testing on the 19 wells and that it was to be completed in February.

Honor Rancho's history of gas leaks

Another storage facility SoCal Gas maintains is an oil field in the Santa Clarita Valley known as Wayside Honor Rancho near I-5 and Highway 126.

The Honor Rancho (later named Pitchess Detention Center) has been county jail property since 1938. It was where people convicted of public drunkenness and other crimes could work off their sentences in the sunshine and clear air. Drilling rig workers were warned to lock their vehicles, and to bring no weapons, booze or drugs onto the property.



The gas company leases the land from Los Angeles County, paying nearly $400,000 per year, said county spokesman David Sommers.

Fourteen of Honor Rancho's 34 active gas wells were drilled in the '50s and '60s as oil wells by Chevron Texaco. SoCal Gas bought the field in 1975 and converted it to gas storage. Today, it holds about 26 billion cubic feet of gas that could be sold to customers.

In 1991, a well known as WEZU 30 was leaking badly enough that it placed the integrity of the entire field in peril. SoGal Gas experts writing in the Oil & Gas Journal in 1991 said that workers accidentally punched through the well casing into the storage reservoir, triggering the leak.

It's not clear exactly how much natural gas escaped, but just as with the leak at Aliso Canyon, it took months to resolve, and the same method was used. A second well, called a rescue well, was drilled alongside the leaking one, and a tool that uses electromagnetic fields was sent down the second well to pinpoint the location of the leaking well.

Back in 1991, it was a very new method for SoCal Gas, which had hired contractors to do the work, and there were some mishaps. At one point, the rescue well unintentionally bored through the leaking well 9,860 feet below the surface after readings from the magnetic tool told them they should have been about four feet away from the well.

Gas migration was a problem at the Honor Rancho field in 1996. The company reported that gas has migrated beyond the intended reservoir, however details of the severity of the incident were not available. Gas migration can be caused by "a lack of structural integrity of the geologic reservoir or due to a man-made conduit, such as a poor cementation in the storage well casing strings," the company said.

Honor Rancho has 34 active gas wells today.

Montebello's gas field closure

SoCal Gas has closed one major gas storage field in recent years. The Montebello Natural Gas Storage Facility was decommissioned in 2000, and even though it is no longer a gas storage project, that site still has 25 active gas wells, according to DOGGR well records. Five of those were drilled in the 1960s.

The Montebello Gas Storage Facility opened in 1956 on a former oil field drilled in the 30s. It was big, with capacity for 40 billion cubic feet of natural gas that could be delivered to customers and a similar amount held underground to keep the field pressurized. It holds about half what the Aliso Canyon field holds.

The line of dots indicate gas storage and oil extraction wells on the grounds of the Montebello Natural Gas Storage Facility in Montebello. CA Division of Oil, Gas and Geothermal Resources

The CPUC fined SoCal Gas $3.5 million in 2000. The commission alleged the company obtained an order permitting it to force homeowners to sell their underground mineral rights at below-market prices. The company had told the commission the gas field was vital to its operations.

But shortly after that decision, the gas company told the CPUC it no longer needed the gas field and wanted to sell it. Homeowners complained. SoCal Gas admitted no wrongdoing in the settlement and agreed to close the gas field. The case halted the sale of the Montebello gas field.

Incidents like that left some residents mistrustful of the company.

Yvonne Watson is a Montebello resident who has monitored the gas field and would like to see it shut down.

"It just really burns me up that there are so many things happening here and this is one of these things where you trust these companies to do the right thing, but it feels like they don't do the right thing unless they absolutely have to," Watson said.

SoCal Gas, in the settlement of a different lawsuit, agreed to shut down the field in 2000.

In a written statement, gas company spokeswoman Melissa Bailey said that most of the 46 active wells at Montebello are depleted. However, some natural gas continues to be pulled out of the field and put into the SoCal Gas distribution network as part of the process of shutting down the field. That gas is known as "cushion gas" that is put into the field to pressurize it.

The field now produces oil, and the small amount of gas and water that come out with the oil are reinjected back underground, Bailey said.

"A leak similar to Aliso is highly unlikely since Montebello is not a pressurized storage facility," she said.

The future of Aliso Canyon's wells

Aliso Canyon Natural Gas Storage Facility in the Santa Susanna foothills above Porter Ranch is Southern California Gas Co.'s largest natural gas storage field. It has 91 active gas storage wells according to state regulator data. (SoCal Gas often says it has 114 gas wells at Aliso, the others are idle or used for observation.)

Here is when the still-active wells were first drilled.

Decade # Drilled 1940s 25 wells 1950s 7 wells 1970s 32 wells 1980s 5 wells 1990s 10 wells 2000s 8 wells 2010 to present 4 wells

SoCal Gas acquired the depleted oil field and transformed it into a gas storage field in 1973. In later years, the company continued to drill wells at Aliso Canyon even as home-building continued a mile or two downwind in Porter Ranch.

"This was a 65-year-old well that was subject to only the most rudimentary annual testing," said Rep. Brad Sherman, whose San Fernando Valley district includes part of Porter Ranch. He moved to the community about a year ago. He said he smelled the gas but did not relocate his family during the months-long leak.

SoCal Gas said the leaking well had a subsurface safety valve that was removed in 1979 and not replaced.

It's not clear from DOGGR's records how many of the wells drilled in the past 25 or so years were put in to replace aging wells in the SoCal Gas fields.

There have been calls from some residents and others to shut down the Aliso Canyon storage facility. SoCal Gas has repeatedly said that field is vital to the energy reliability of Southern California.

Its operation is already mostly stalled now due to a state order that injections of gas into the field be halted until the time-consuming inspection of other old wells is completed.

SoCal Gas has set up a community resource center on Tampa Avenue near the entrance to their Aliso Canyon Storage Facility near Porter Ranch. Maya Sugarman/KPCC

The state and AQMD had also ordered the amount of gas in the reservoir to be drawn down to reduce the pressure on the leaking well and other wells. So today, the storage field holds a minimal amount of gas, about 5 billion cubic feet, just enough to get the region through a cold snap or a few very hot days when power plants burn natural gas to meet higher demand.

One of the big questions remaining about the Aliso Canyon field is whether and when it will return to its normal functioning as the main gas reservoir serving the Los Angeles and Orange County areas.

A bill by Sen. Fran Pavley, D-Agoura Hills, is working its way through the legislature that would place a moratorium on further gas injections to the reservoir until all the wells are inspected, not just 18 older wells covered by a state order.

Despite those calls for the field to be shut down or restricted, SoCal Gas is in the process of a major expansion.

The company is partway through a $201 million project to build new turbine engines that are used to force gas underground. Those new turbines would increase the capacity of the underground gas field by 50 percent. That project was approved in 2013 by the CPUC.