LONDON (Reuters) - Britain's largest natural gas storage site, Rough, will not be available for gas injection until the end of April next year, operator Centrica Storage Ltd (CSL) (CNA.L) said on Wednesday.
Concerns about the integrity of wells at the Rough site, off England's east coast, prompted Centrica to impose limits last year on how much gas could be stored, as a safety precaution.
After investigations, Centrica initially shut the facility for injections and withdrawals of gas. Withdrawals resumed in December but injections were put hold until at least July 1, which has now been extended to April next year.
Gas withdrawal at Rough is unaffected by the latest move.
Britain depends on stored gas reserves to help manage winter demand spikes and to ensure security of supply. Rough is the largest storage site in the country but is more than 30 years old and repeated outages have shown its vulnerability.
"CSL has concluded that, as a reasonable and prudent operator, based upon the results of its well testing program, Rough cannot safely re-commence injection operations in the 2017/18 storage year," the company said in a statement.
The UK gas storage year runs from the start of May to the end of April, a Centrica spokesman told Reuters.
After testing two thirds of the wells, CSL said results confirmed several possible issues in a number of the wells, without giving details. It said tests would now be conducted on the remaining wells. It did not give a timeline for completion.
The announcement was largely expected due to the age of the facility and repeated outages which have shown its vulnerability, analysts said.
"Our forecasts for this summer took the view that Rough Storage would not be able to return this gas year, and there are significant concerns whether or not it will be operational again," said Oliver Sanderson, gas analyst at Thomson Reuters.
He said the news would push UK gas prices higher, especially for the third quarter and the coming winter.
The UK gas contract for winter 2017 (TRGBNBPSH8) was up 0.62 pence at 46.57 pence per therm at 0900 GMT.
(Reporting by Nina Chestney and Swati Verma in Bengaluru; Editing by Edmund Blair)