Jan. 29 (Bloomberg) -- Chevron Corp.'s Kazakh venture, TengizChevroil LLP, increased crude oil extraction after starting up a gas injector.

The addition of 90,000 barrels a day brings current capacity to about 400,000 barrels a day, Chevron said today in a statement. Capacity will reach 540,000 barrels a day in the second half when more facilities at the Tengiz field are added.

The ``expansion of the world's deepest producing supergiant oil field is another step forward in partnering with Kazakhstan,'' Jay Johnson, managing director of Chevron's Eurasia business unit, said in the statement.

Kazakhstan, the holder of 3.3 percent of the world's proven oil reserves, has to export most of its oil through a pipeline across Russian territory. Chevron is boosting Kazakh output against a background of Russian opposition to plans to expand the company-led Caspian Pipeline Consortium to pump more crude through Russia to a Black Sea port.

TengizChevroil started the sour gas injection unit, which pumps some of the extracted gas back into the Tengiz field to push out oil. A gas refinery is now`` separating the natural gas for injection while also stabilizing and sweetening the crude oil,'' Chevron said in the statement.

When the project reaches full capacity, about one-third of the sour gas produced will be injected back into the reservoir, while the remaining volumes will be processed as commercial gas, propane, butane and sulfur, the company said.

To contact the reporter on this story: Eduard Gismatullin in London at egismatullin@bloomberg.net

Last Updated: January 29, 2008 05:21 EST