agreement for a key Caspian Sea oil venture, more than doubling its ownership stake. State energy firm KazMunaiGaz will now hold more than 16.81% in the Kashagan venture, equivalent to the stakes held by its partners Eni, ExxonMobil, Shell, and Total. ConocoPhillips of the US and Japan’s INPEX each retain 8.4% and 7.56% respectively. The…