Tengiz is one of the world's deepest and most complex fields due to high levels of sulphur and harsh weather conditions

The energy giant is spending nearly $50 billion to expand the Tengiz oil field, allowing it to pump one million barrels a day.

Chevron said on Friday it had started production at a $48 billion expansion of the giant Tengiz oilfield which will bring its output to around 1% of global crude supply.

Chevron said on Friday that it has started producing oil from an expansion at Kazakhstan’s Tengiz oilfield, which could help lift the project’s total output to 1 million barrels per day at full capacity.

Chevron achieves first oil at Kazakhstan's Tengiz field, completing $48B expansion project, boosting production to 1% of global crude supply.