--> ABSTRACT: The Challenge of Petroleum Exploration in the Gorontalo Frontier Basin, North Sulawesi - Indonesia, by Cholidy H. Reminton; #91020 (1995).

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The Challenge of Petroleum Exploration in the Gorontalo Frontier Basin, North Sulawesi - Indonesia

Cholidy H. Reminton

The Gorontalo Basin is located in the neck and right arm of North Sulawesi, classified as untested basin in a frontier area.

PERTAMINA in 1991 conducted an Airborne Laser Fluorescence (ALF) survey in the Gorontalo Basin. A number of fluors can be recognized on the sea water surface in the Tomini Bay. In conjunction with the ALF study, PERTAMINA in 1992 carried out geological and gravity field studies in the area. Oil and gas seepages were found during the survey. In the Tomini Bay, gas seeps were found as bubble gas which coincided with the fluors.

The result of the study suggests that there are two basins existing in the Tomini Bay; they are the Gorontalo Basin in the east and the Tomini Basin in the west. These basins are separated by the Una Una High. Based on tectonic development, the Gorontalo Basin is a back arc formed when subduction began in the Palogene. The North Arm of Sulawesi forms an active volcanic are and separates the Minahasa fore arc from the Gorontalo back arc. The Tomini sub basin, as a part of the Gorontalo Basin, is believed to be a fore-arc basin formed by the subduction effecting the western part of Sulawesi.

Geological data from the onshore of North Sulawesi indicate that shales and claystones of Tinombo Group, deposited in the back arc basin during Paleogene time (Eocene-Oligocene) could be source rocks for hydrocarbons. Sandstones from submarine fan deposits of the Tinombo Group (Eocene-Oligocene), reef of the Ratatotak Formation (lower to middle Miocene), clastic sediments and limestones of the molasse Celabes (upper Miocene-Pliocene) have potential to be reservoir rocks. A number of all oil and gas seepages onshore and offshore of Tomini Bay suggest that Paleogene source rocks are mature enough to generate hydrocarbons.

Since the Government of Indonesia released the Incentive Package in 1993, the Gorontalo Basin, as a part of the Eastern Indonesia, becomes more promising for hydrocarbon exploration.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995