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Abstract: Sequence Stratigraphy and Unconformities of the Mesozoic: Implication for Hydrocarbon Exploration in the Eastern Part of Indonesia

Lukman Kartanegara, Slamet Riadhy

The exploration activity in the eastern part of Indonesia is focused on the Tertiary and Mesozoic objectives. During the last seven years, the Mesozoic success ratios are higher compared with the Tertiary; therefore the Mesozoic target has become an interesting exploration target in this area.

Sequence stratigraphy and unconformity studies were carried out; well-log seismic and sequence stratigraphy form the core of this study for fully integrated analyses of stratigraphic-trap model, reservoir characteristic and depositional-facies evaluation.

Sequence stratigraphy analyses are able to recognize several depositional sequences. Two types of production reservoirs are recognized as follows: nearshore-deltaic to deep marine turbidite of highstand-systems tract and oolitic grainstone-packstone, nearshore to outer shelf of late highstand-systems tract. A series of major unconformities are recognized at near top and base of Mesozoic, within Cretaceous, Jurassic and Triassic in the Microcontinental Block, Marginal Rift Graben, Island Arc, and Peri Cratonic Graben. It's caused by a regional compression event, transpressional reactivation, uplift and global changes of sea level in a complex area of collision.

The results of the study indicated that the erosional truncation trap below regional unconformity, facies changes and sand pinchout to form an interesting exploration objectives. The lowstand-systems tract, paleokarst at top of limestone, forms a new interesting exploration target in the future, while the graben deposits form a less attractive exploration target due to problems of hydrocarbon sourcing.

AAPG Search and Discovery Article #90951©1996 AAPG International Conference and Exhibition, Caracas, Venezuela