(New throughout, adds details)
Jan 3 (Reuters) - Southern California’s gas utility on Thursday extended its request for consumers to reduce natural gas use through the weekend, to avoid straining the system as cold weather lingers over the area.
Regional gas supplies were expected to remain tight this winter due to limitations on several Southern California Gas Co (SoCalGas) pipelines and reduced availability of the utility’s biggest storage field at Aliso Canyon in Los Angeles, following a massive leak between October 2015 and February 2016.
SoCalGas, a unit of California energy company Sempra Energy , said it pulled gas from all four of its storage fields during the cold this week, including Aliso Canyon.
When Aliso Canyon returned to service after the leak, the state mandated the facility was only to be used as an asset of last resort to maintain system reliability after other storage facilities and pipelines have been exhausted.
“Without withdrawals from Aliso Canyon, increased demand...may have resulted in further curtailments to non-core customers,” SoCalGas said in a customer notice. Non-core customers include electric generators and some large industrial businesses.
The U.S. National Weather Service issued a freeze warning for some inland cities in Southern California like Riverside.
In addition to asking consumers to reduce gas used to heat homes and businesses, SoCalGas also extended a system-wide voluntary curtailment notice to electric generators from Wednesday through Friday.
Consumer gas demand was expected to reach 3.6 billion cubic feet (bcf) on Thursday, 3.4 bcf on Friday and 3.0 bcf on Saturday and Sunday after hitting 3.8 bcf on Wednesday. One billion cubic feet is enough to supply about 5 million U.S. homes for a day.
State agencies forecast SoCalGas’ pipelines and storage facilities could send out up to 4.1 billion cubic feet per day (bcfd) this winter before the utility would have to tap Aliso Canyon, according to a report in October.
SoCalGas can get about 2.7-3.3 bcfd from its pipes and the rest from storage, depending on how many pipeline outages and reductions the utility is able to fix, according to a state report.
If needed, Aliso Canyon can deliver around 1.0 bcfd. But like all storage facilities, the amount of gas it can deliver will decline rapidly as pressure in the cavern decreases when the utility pulls fuel out.
Reporting by Scott DiSavino; Editing by Bernadette Baum and David Gregorio