(EnergyAsia, May 3, Thursday) — Thai state upstream company PTTEP said its fully owned subsidiary, PTTEP International Limited (PTTEPI), plans to raise its stake in an offshore block in the Gulf of Thailand from 15% to 21.375%.  Its partners in Petroleum Concession No. 4/2546/61 or Block G4/43 are Chevron Offshore (Thailand) Ltd and Mitsui Oil…