Kazakhstan, one of the world's 10 biggest oil producers, increased pressure on international companies operating in the country on Tuesday, calling for improved contract terms. The move is the latest in a string of claims,

Chevron (NYSE:CVX) said Friday it achieved first oil from newly built production and processing facilities at Kazakhstan's huge Tengiz oil field, completing a $48B expansion that will bring its production to ~1% of global crude supply.

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