The Central Valley natural gas storage project involved the development of an underground natural gas storage facility in the state of California, US. The project was undertaken by Central Valley Gas Storage, a wholly-owned subsidiary of AGL Resources.
The project converted the depleted Princeton gas field, which is located 2,200ft underground, into a multicycle storage facility. The Princeton field produced 9.7 billion cubic feet (Bcf) of gas between 1954 and 1991.
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The maximum storage capacity of the new facility is 11Bcf of gas and its maximum withdrawal and injection capacity is approximately 300 million standard cubic feet (MMscf) a day. Natural gas is drawn from the facility, depending on customer demand.
The project received the Certificate of Public Convenience and Necessity from the California Public Utility Commission (CPUC) in October 2010. Construction works on the project commenced in April 2011. The facility started firm storage services in April 2012 and commercial operations in June 2012, exporting 4.5Bcf of gas by the end of that year.
The Central Valley project generated 300 jobs during construction and generated eight permanent jobs. The Central Valley project generates LNG for Pivotal LNG, a wholly owned subsidiary of AGL Resources, to support its business of selling LNG as a substitute fuel. It also helps in expanding the current natural gas supply network in California.
Central Valley project infrastructure
The Central Valley project site covers an area of 246.5 acres. The Princeton field reservoir is made of the Kione formation of the Cretaceous age, which is ideal for gas storage due to its high porosity and permeability. These properties ensure high rates of injection and withdrawal.
To facilitate gas injection and withdrawal, several above ground components were built. These components include a well pad site spread across a 3.1 acre site, including one vertical well and eight directional wells for gas injection and withdrawal.
An existing test was converted into a saltwater disposal well to dispose the saltwater produced during gas withdrawal. This well is connected to the well pad site through an 80ft-long, 6in-diameter water drain pipeline.
Three of the existing wells were converted into observation wells for use at the facility. Re-entry into one plugged gas well was made and used as an observation well. A new well was also drilled for use as an additional observation well. The observation wells are used to monitor the pressure and location of the gas in the field reservoir.
A 10,650hp compressor station, spread over a ten acre site, also formed part of the project. This station features three 3,550hp Caterpillar 3612 LE natural gas engines and three Ariel JGC / six reciprocating gas compressors.
Other components of the compressor station include three triethylene glycol dehydration units and reboilers, three natural gas aftercoolers and metering and regulation facilities. The compressor station included other related infrastructure, such as an auxiliary building comprising a control room and office, a 3,500ft-long electrical distribution line and a domestic water well.
The well pad site is connected to the compressor station through a 1,950ft-long, dual gathering line system with a 16in diameter.
Connection
The Central Valley facility is connected to Pacific Gas and Electric (PG&E)’s gas transmission system. A 14.9-mile long gas pipeline links the compressor station to PG&E Line 400 / 401.
The pipeline has a diameter of 24in. A metering station was built near PG&E Line 400 / 401 over an area of one acre.
Temporary links to PG&E Line 172 were provided by a 170ft-long, 8in-diameter gas pipeline and a rental compressor unit. A meter skid also formed part of the temporary connection.
By interconnecting with PG&E, Central Valley’s customers will be supplied with natural gas from the Alberta, Rockies, San Juan and Permian basins.
Customers can also have access to future potential resources developed in the West Coast.
