Aliso Canyon withdrawal goal cut as heat abates

OREANDA-NEWS. October 05, 2016. California regulators have pared the minimum amount of emergency natural gas that SoCal Gas must be able to withdraw from its Aliso Canyon underground storage field as cooler temperatures trim summer electric demand.

SoCal Gas is working to return 20 to 25 injection wells at the 86 Bcf (2.4bn m?) Aliso Canyon storage field to service following a massive leak that began nearly a year ago and allowed nearly 5 Bcf to escape over a four-month period.

Aliso Canyon plays a critical role in supplying gas to power plants and numerous oil refineries and agricultural processing plants in the Los Angeles basin.

While a state-ordered moratorium on gas injections at Aliso Canyon continues, 25 of the 114 wells at the Los Angeles County storage field have now passed the battery of safety tests, according to the California Department of Conservation's division of oil, gas and geothermal resources (DOGGR) website.

In June, the California Public Utilities Commission (PUC) directed SoCal to make sure Aliso Canyon had enough wells available to withdraw a minimum of 420mn cf/d, less than one-quarter of the field's pre-leak withdrawal capacity, if needed to reduce risk that a gas curtailment that might lead to electric blackouts across southern California.

The PUC recently lowered the minimum withdrawal capacity by 51pc to 207mn cf/d.

"This new reduced requirement reflects a lower risk as a result of the effective use of mitigation measures and moderating weather as the end of the summer season is approached," PUC executive director Tim Sullivan said in a letter to SoCal officials dated 28 September.

Neither regulators nor SoCal have said whether Aliso Canyon met the earlier 420mn cf/d target because emergency regulations issued by DOGGR require wells that return to service be reconfigured to only flow gas through inner metal tubing rather than from the tubing and the well casing as was common before the leak.

A joint report from state agencies said SoCal was preparing to draw gas from Aliso Canyon during a mid-June heat wave, but above-normal temperatures moderated and the electric grid was able to meet load without problems.

Southern California avoided rolling outages over the summer by utilizing tighter operational measures and increased coordination with the California Independent System Operator (ISO).

Cold weather presents a much greater challenge for the SoCal system because gas demand grows significantly in the winter to heat homes and businesses, as well as to produce electricity. Generators remain the first to be curtailed if gas supplies are strained.

ISO board members yesterday approved extending a majority of the summer mitigation measures until November 2017 at least

"We are now building on that experience to ensure we have the best practices in place to meet winter heating demand and still have the gas needed to run the region's power plants," said ISO president Steve Berberich.

The ISO staff said its expectation is "that the Aliso Canyon facility will not be operational during the bulk of 2017."

SoCal officials told state regulators in late August that they might ask DOGGR to certify the Aliso Canyon field as safe to operate around 1 October, but the timing of a request remains uncertain.

"We're diligently working with state officials to complete a comprehensive safety review of the Aliso Canyon storage field to support the reliability of natural gas and electricity services," said SoCal's Melissa Bailey. "Our focus is on safely completing the review process in compliance with all regulations and state laws – not to meet a specific date."

SoCal said it will need until 17 October to complete pipeline corrosion inspections ordered by the PUC late last month.

The PUC action followed discovery of a pinhole leak from above-ground pipeline equipment at one Aliso well currently isolated from the reservoir. SoCal said it identified eight additional wells with similar characteristics, but found "no significant evidence of pitting" in the wells that have been fully tested.

SoCal said it has reduced pressure in the withdrawal lines and will complete the internal testing by 17 October.