Kashagan consortium looks at ways to restart oil output safely

ALMATY (Reuters) - A consortium developing the giant Kashagan oilfield in Kazakhstan said it was considering "technological scenarios" to resume production safely after a gas leak from a pipeline led to a halt in October.

The North Caspian Operating Company (NCOC) gave no start-up date in a statement on Wednesday. It reiterated earlier comments to Reuters that the specifications for the pipeline were appropriate for conditions at the field, located in the Caspian Sea.

Kashagan, the world's biggest oil find in decades and the most expensive standalone oil project, took an estimated $50 billion and 13 years to start output last September. It was soon shut down, however, due to pipeline leaks that investigators said were caused by stress linked to the presence of hydrogen sulphide gas.

NCOC said an inspection of the field's pipeline network by the so-called Intelligent PIG (Pipeline Inspection Gauge) was in progress.

"This process has been completed for the sour gas line; the raw data are under review and interpretation," it said. "Preparations to implement the inspection of the oil line are currently in process."

The consortium reiterated an earlier statement that it expected to receive the results of the investigation in early 2014 but gave no indication of when output could be restarted.

"The (restart) scenarios would highly depend on the results of data interpretation as well as many other factors," it said. NCOC officials could not be reached for comment.

International oil majors Exxon (XOM.M), Shell (LSE:RDSA), Total (PAR:FP), Eni (MIL:ENI) and Kazakh state oil company KazMunaiGas each hold a 16.81 percent stake in Kashagan. Japan's Inpex has 7.56 percent, and China National Petroleum Corp (CNPC) (CNPET.UL) acquired 8.33 percent in 2013 as ConocoPhillips (CP.N) exited.

The specifications of the pipes used at Kashagan fully meet the requirements of the NACE (National Association of Corrosion Engineers) standards and best practices in international oil and gas field development, NCOC said.

"As was previously communicated, the sour gas line was designed to withstand the expected H2S content and the presence of water."

The Kashagan project aims to produce up to 1.66 million barrels a day - as much oil and OPEC member Angola - from a reserve almost as big as Brazil's, regardless of harsh weather conditions and technological complexity.

Much of its infrastructure is built on artificial islands to avoid damage from pack ice in a shallow sea, which freezes five months a year in temperatures that drop below minus 30 degrees Celsius (-22 F).

NCOC denied some media reports that gas hydrates had caused the pipeline leaks at Kashagan. Gas hydrates are solid, ice-like structures in which gas is trapped inside of water molecules. They may cause partial or complete plugging of gas pipelines.

"To date, Kashagan production facilities have not experienced hydrate formation," the consortium said.

(Reporting by Dmitry Solovyov; editing by Jane Baird)