Irian Jaya is one of the areas in Eastern Indonesia which has interesting hydrocarbon potential. Hydrocarbon had been proven, and some of the prospects have been developed as oil field. Cendrawasih Bay occupies the northern edge of the Bird’s Head Irian Jaya. Many syntheses were made to analyze the hydrocarbon potential on this geologically complex northern portion of Irian Jaya, however little were mentioned about the prospects in Cendrawasih Basin and the basins to the East. Cendrawasih Bay is tectonically bordered by the Oceanic Pacific plate in the North, Lengguru Fold Belt in the West, Central Range in the South and Waipoga Mamberamo basin in the East. The result of the collision between westward moving Pacific plate and the northward Australia Continental plate is a wide Suture Zone consisting of a mixture of intensely deformed Oceanic Crust and Volcanic Assamblage, now forms the basement of the sedimentary basins occupying the Northern Portion of Irian Jaya. It seems most probable that Cendrawasih Bay also underlies by the same rock association. The western border of Cendrawasih Bay is separated from the Lengguru Fold Belt by a zone of right lateral Ransiki Fault. Evidences show that Lengguru Fold Belt and Kemum Block in the west were built up of continental crust of Australia origin. The Waipoga Mamberamo basins commenced during Oligocene as a pull apart basin related to the wrenching between left- lateral Sorong and Tarera Aiduna Faults, ac-comodating the collision between west moving Pacific and Australia Continental plate. Attempt to explore the area for hydrocarbon have been done by several oil companies. Only two of the eleven wells in Mamberamo Basin show indication of gas occurence, although in some localities oil seeps have been reported. Geochemical analysis from core/cutting samples, indicates that Auwewa, Darante, Makats and Mamberamo Formations are a good source rock, and in general the porosity value of the coarse elastic is good enough as reservoir.
Authors : Tonny S.A & Hestu Bagiyo