--> ABSTRACT: Volcanics Oil Bearing In Indonesia, by A. Lukman Kartanegara, R. Nyak Baik, and M. Anditya Ibrahim; #91019 (1996)

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Volcanics Oil Bearing In Indonesia

A. Lukman Kartanegara, R. Nyak Baik, and M. Anditya Ibrahim

The volcanic rock is seldom considered as good reservoir rocks. However, in Indonesia there is a volcanic layer called the Jatibarang Formation in Jatibarang Field, West Java, that has proven to be a producer of oil and gas of adequate amount. The lateral development of this rock extent along the whole of the basin, about 400 km over a Tertiary block-faulting system of the North West Java Basin. It is estimated that the volume of the spread is about 2360 km3. Beside from the primary volcanic rock, the developing reservoir rock could also resulted from rework of massive volcanics or agglomerate, and other volcanic product resedimented as clastic deposits.

The hydrocarbon is sourced from the younger Talang Akar Formation that is in direct contact with the reservoir rock. It migrated through the faults. Present cumulative production has reached 1.2 BBO and 2.7 TCFG, while speculative reserve is estimated at 4.0 BBO and 3 TCFG.

Regionally, the volcanic rock of the Jatibarang Formation where the hydrocarbon is found is the result of eruptions along the magmatic trend during Late Cretaceous. In North West Java Basin, the trapping system includes both the structural and stratigraphic traps. Reservoir analysis yields porosity values of around 16-25% and permeability of around 10 Darcies. It is concluded that there are good opportunities still left for hydrocarbon exploration in volcanic rocks. The study is discussed in detail supported by data from cores and laboratories.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California