Kazakhstan's Tengiz oil field output 20% below plan in December, data shows

MOSCOW, Dec 13 (Reuters) - Output from Kazakhstan's biggest oil field Tengiz, operated by U.S. major Chevron (CVX) , remained 20% below its scheduled plan on average in December, helping the country to comply with its OPEC+ output target, Reuters estimates based on Kazakh energy ministry data and analysis service SAC TEK showed.

Tengiz was expected to restore full oil output early in December following a maintenance that had started late in October.

Kazakhstan, which relies on Tengiz and the Karachaganak and Kashagan fields for most of its production, is subject to output targets as a member of OPEC+, an alliance of OPEC and other top oil producers led by Russia.

The production decline may help Kazakhstan comply with its output quota under an agreement with the OPEC+ group.

Kazakhstan's oil production excluding gas condensate for the 12 days of December is at 1.46 million bpd, according to the Reuters estimates, when using a conversion factor of 7.5 barrels per 1 metric ton, is in line with the country's target within OPEC+, which is 1.468 million bpd until April 2025.

The operator of the Tengiz field, Tengizchevroil (TCO), did not immediately respond to Reuters' request for comment. The Kazakh Ministry of Energy declined to comment.

Daily Tengiz oil production for the 12 days of December was at about 62,100 metric tons (494,170 barrels) compared to the planned 77,471 tons (616,700 barrels).

Oil production at Tengiz fell to 61,000-63,000 tons per day (around 510,000 barrels per day) in November, down 21% from the October average, due to maintenance.

Tengiz boosted oil output to a record high in early October to 699,000 barrels per day (bpd) from 687,000 bpd in September shortly before the maintenance had started.

Chevron (CVX) and its partners plan to expand output at the Tengiz project to 850,000 bpd in the first half of 2025. Expansion costs at the project stand at around $49 billion.

Chevron (CVX) owns a 50% stake in the venture. Exxon Mobil (XOM) controls 25%, KazMunayGaz has a 20% stake, and Russia's Lukoil owns 5%.

(Reporting by Reuters; Editing by Toby Chopra)