Oil output in Kazakhstan, one of the world's 10 biggest producing countries, returned to growth last month and matched an all-time high, as the Chevron-led (CVX.N) Tengiz field ramped up, a source familiar with the data told Reuters on Tuesday.
Kazakhstan has persistently exceeded quotas set by OPEC+, which groups the Organization of the Petroleum Exporting Countries and other producers led by Russia.
Its overproduction has angered some of the group's members, sources have told Reuters, and has been one of the reasons for faster-than-expected output increases from OPEC+ as it fights for market share and seeks to punish those breaching curbs with lower international prices.
The source, speaking on condition of anonymity because of the sensitivity of the issue, said Kazakhstan's daily crude oil output, excluding gas condensate, a type of light oil, jumped in June by 7.5% from May to 1.88 million barrels per day.
That matched an all-time high reached in March and was above Kazakhstan's quota of 1.5 million bpd for June under the OPEC+ deal.
Total oil and gas condensate production in Kazakhstan rose to 2.15 million bpd last month from 2.02 million bpd in May, according to the source.
Daily oil output at Tengiz, Kazakhstan's largest oilfield, jumped in June to 953,000 bpd from 813,200 bpd in May, the source said.
Chevron embarked in January on a $48 billion expansion of Tengiz, which is one of the world's deepest and most complex fields due to high sulphur levels and harsh weather conditions.
Tengizchevroil, the operator of Tengiz, has not commented on its commercial activity, while Kazakhstan's energy ministry did not immediately reply to a request for comment.
It has said it was committed to the OPEC+ deal, but also said the country's national interest is of paramount importance.
Eight members of OPEC+ - Saudi Arabia, Russia, Kuwait, Iraq, the United Arab Emirates, Kazakhstan, Oman and Algeria - will meet on July 6 to decide on their production policy for August.
Four delegates from the group told Reuters that OPEC+, is set to announce another big increase of 411,000 barrels per day in production for August.
According to the source and Reuters preliminary calculations, the country's crude oil production without condensate rose in the first half of the year by 13% from the same period a year ago to 1.79 million bpd.
Kazakhstan may exceed its previous oil production forecast by around 2% this year following an upgrade to output at its largest Caspian oilfields, Reuters calculations, based on data from state-owned energy company KazMunayGaz (KMGZ.KZ), showed on Monday.
