Aliso Canyon Oil Field

Aliso Canyon Oil Field

Company type	Subsidiary facility
Industry	Oil extraction, Natural gas storage
Founded	1938
Headquarters	Los Angeles County , United States
Area served	Western United States
Products	Oil, Natural gas storage
Owner	Southern California Gas Company (primary operator)

The Aliso Canyon Oil Field, also referred to as the Aliso Canyon Natural Gas Storage Field or Aliso Canyon Underground Storage Facility, is a site for oil extraction and natural gas storage situated in the Santa Susana Mountains of Los Angeles County, California, just north of the Porter Ranch area. Initially discovered and developed in 1938, it reached its peak oil production during the 1950s but continues to operate today. In 1973, Southern California Gas Company transformed the depleted Sesnon-Frew zone—an oil and gas-bearing formation—into a reservoir for natural gas storage. This reservoir ranks as the second-largest natural gas storage facility in the western United States, with a capacity surpassing 86 billion cubic feet. Southern California Gas owns three additional gas storage fields: La Goleta Gas Field, Honor Rancho, and Playa del Rey.

By 2016, oil extraction persisted from 32 active wells managed by Southern California Gas Company, The Termo Company, and Crimson Resource Management Corp. The gas storage reservoir is accessed through 115 injection wells and includes an internal pipeline network extending roughly 38 miles.

Geographic setting

Positioned on the southern flank of the Santa Susana Mountains, an east-west trending range that divides the San Fernando Valley to the south from the Santa Clarita Valley to the north-northeast, this field features productive wells located at elevations exceeding 3,000 feet, making it one of California’s most elevated and rugged oil fields. Entry to the area is regulated by a security checkpoint at Limekiln Canyon Trail and Sesnon Boulevard.

Land surrounding the field comprises industrial zones related to oil and gas operations, open spaces, parklands, and residential neighborhoods to the south. The mountain regions to the west, north, and east are designated as Significant Ecological Areas. Adjacent to the northeast lies the Michael D. Antonovich Open Space Preserve, while several parks within Porter Ranch border the southern edge.

Water runoff drains southward into the San Fernando Valley via Mormon, Limekiln, and Aliso Canyons before eventually reaching the Los Angeles River and Long Beach. Vegetation includes native oak woodlands and Venturan sage scrub, with non-native grass species found near developed infrastructure. The area experiences a Mediterranean climate characterized by warm, dry summers and mild winters with precipitation; snowfall is uncommon but can occur at higher altitudes. Wildfires are a frequent hazard here, notably affecting parts of the storage facility during the 2008 Sesnon Fire, which burned approximately 14,000 acres.

Geology

The Aliso Canyon field comprises multiple sedimentary layers containing oil and gas within a southeast-plunging anticline, bordered by the Santa Susana Fault Zone to the north and the Frew Fault to the west-northwest. These faults form a structural trap that retains hydrocarbons within the formations. The Tertiary sedimentary sequences display a stratified arrangement of permeable oil- and gas-bearing units interspersed with impermeable layers. Older Cretaceous formations have been thrust over these younger deposits along the Frew Fault.

The uppermost producing interval is found in the Pliocene-aged Pico Formation, which includes several zones such as Aliso, Porter, Upper, Middle, and Lower Del Aliso at depths ranging from about 4,500 to 8,000 feet. Beneath this lies the Middle Miocene Modelo Formation, followed by deposits of the Eocene Llajas Formation. These permeable layers collectively form what is known as the Sesnon-Frew zone—the largest productive interval in the field—which serves as Southern California Gas’s primary gas storage reservoir. This zone averages around 9,000 feet deep and approximately 160 feet thick. Underlying these are non-productive marine sediments from the Cretaceous period along with deeper crystalline basement rocks dating from Cretaceous or older eras.

History and production

The Santa Susana Mountains, forming part of the Ventura Basin's anticline structures, have long been a focal point for oil exploration activities. Near this area lies the Pico Canyon region within the Newhall Oil Field, notable for hosting the western United States' oldest commercially productive oil well. In 1938, J. Paul Getty's Tidewater Associated Oil Company drilled the Aliso field’s initial discovery well, successfully tapping into oil at a depth of 5,393 feet within the Porter zone. Following this, additional zones such as Del Aliso (discovered in 1938) and Sesnon-Frew (discovered in 1940) were identified. Early operators in the field included Tidewater, Standard Oil of California, Porter Sesnon, Carlton Beal and Associates, and M.L. Orcutt. By 1959, production had expanded to 118 active wells yielding over 32 million barrels of oil.

The Sesnon-Frew zone was characterized by a prominent gas cap; certain wells produced exclusively gas and required further deepening to access oil. Excessive extraction led to legal conflicts among Standard Oil, Tidewater, and Carlton Beal over gas wastage concerns. To mitigate this issue, the State Oil and Gas Supervisor imposed production limits on the Sesnon pool aimed at reducing waste.

In response to declining conventional output, enhanced recovery efforts using waterflooding commenced in 1976, particularly targeting the Del Aliso zone. This method involves reinjecting produced water to sustain reservoir pressure and enhance oil extraction efficiency despite gradual dilution effects.

Residential growth in the San Fernando Valley began encroaching near the field during the 1960s with developments like Porter Ranch; substantial expansion continued throughout the 1970s into the early 2000s. These projects featured master-planned communities and gated neighborhoods, contributing to one of the most affluent residential areas adjacent to Southern California Gas Company’s property boundaries.

Conversion to gas storage

By the early 1970s, oil reserves in the Sesnon zone were largely exhausted. However, its sizeable and geologically stable reservoir located approximately 9,000 feet underground—and centrally situated within Pacific Lighting's distribution network (a predecessor to Southern California Gas Company)—made it an optimal candidate for natural gas storage. Pacific Lighting secured rights from Getty's Tidewater Petroleum and transformed numerous aging oil wells from the 1940s and 1950s into gas injection wells. This repurposed site evolved into what is now known as the Aliso Canyon Natural Gas Storage Facility—the largest gas storage reservoir owned by SoCalGas and second largest in the western United States. The facility plays a crucial role in balancing seasonal natural gas demand by injecting gas during warmer months and withdrawing it during peak winter periods. Its strategic location combined with extensive pipeline infrastructure enhances service reliability across SoCalGas’s service territory.

In 2009, SoCalGas proposed modernization efforts involving replacement of outdated gas turbine compressors with advanced electric compressor units, aiming to increase injection capacity from 300 million to 450 million cubic feet daily. The upgrade plan also encompassed relocating security buildings, constructing a new electrical substation, and enhancing transmission and telecommunications systems. After undergoing environmental review under California’s CEQA regulations, construction activities commenced in 2014.

Due to the facility’s age, many wells have required extensive maintenance; as of July 2014, approximately half of its 229 wells were more than 57 years old. Various casing, tubing, and wellhead leaks have been documented—for instance, multiple well leaks occurred in 2013. In 2008, one well exhibiting elevated surface annulus pressure—indicative of a significant subsurface leak—was taken offline after corrosion was detected along a 600-foot section of casing deep underground. To address these challenges, SoCalGas implemented a Storage Integrity Management Program with dedicated funding and submitted it for approval to the State Public Utility Commission in 2014.

Beyond SoCalGas’s facility perimeter, Termo Company and Crimson Resource Management Corporation continue producing oil from shallower formations. As of late 2015, Termo planned to expand its operations by adding twelve new wells to their existing fifteen but postponed these plans following the October 2015 methane gas release incident at SoCalGas’s Standard Sesnon 25 well.

2015–2016 Methane Gas Release Incident

On October 23, 2015, a rupture in the casing of an 8,750-foot injection well triggered a significant methane gas leak, discharging approximately 60 million cubic feet of methane each day until pressure was alleviated. This well, known as Standard Sesnon 25 ("SS 25"), was originally drilled in 1953 and repurposed for gas injection in 1973. Due to its isolated location at the time, it was not equipped with a blowout prevention valve. The resulting methane plume, containing oily droplets and strong odors, compelled the evacuation of more than 6,000 households. Southern California Gas Company (SoCalGas) assumed responsibility for relocation expenses and installed air purification units in around 10,000 residences.

In response, SoCalGas initiated drilling a relief well on December 4, 2015, aiming to intercept and seal the compromised well from below. The relief well reached its target depth on February 11, 2016, enabling the introduction of heavy fluids to temporarily suppress the gas discharge. A permanent seal was successfully established on February 18, 2016. This event emitted over 100,000 metric tons of natural gas into the atmosphere, representing the most substantial release of its kind recorded in U.S. history.

Subsequently, in March 2016, Termo Company faced a $75,000 penalty for channeling methane emissions from a separate leak. The California Division of Oil, Gas, and Geothermal Resources characterized these actions as "brazen and intentional violations."

Governor Jerry Brown responded by issuing an executive order halting all natural gas injections until comprehensive inspections for corrosion and leaks were completed on all wells. Further strengthening this stance, he enacted Senate Bill 380 on May 10, 2016, which prolonged the suspension of gas injection activities and mandated evaluation regarding the potential permanent closure of the Aliso Canyon storage site.