PAYENBERG, TOBIAS H. D.¹, SIMON C. LANG², GEORGE P. ALLEN², and ROBERT KOCH^3
1School Of Natural Resources Sciences, Queensland Univ. of Tech., Brisbane, Australia; current address: Geology Department, Univ. of Toronto, Toronto, Canada
²School Of Natural Resources Sciences, Queenland Univ. of Tech., Brisbane, Australia
³Vico Indonesia, Jakarta, Indonesia

Abstract: Delineation Of Deltaic And Alluvial Channel Orientations Using Paleocurrents And Facies Analysis - An Example From The Kutai Basin, East Kalimantan, Indonesia

Fluvial dominated, deltaic distributary channels and the amalgamated alluvial channels constitute the major hydrocarbon reservoirs in the onshore part of the Kutai basin. A large number of cores, electric logs and outcrops, provide the unique opportunity to integrate surface and subsurface data to improve reservoir characterisation. Paleocurrents indicate a southerly flow trend of the single storey distributary channels throughout the studied succession. The amalgamated alluvial channel orientation is mainly from the west to the east.

The Mahakam delta has been infilling the Kutai basin since the lower Miocene. It was locked into place towards the north of the study area during the middle Miocene, accounting for the southerly directed flow of the distributary channels. Syndepositional differential subsidence with north-south striking fold axes might also have influenced this orientation. Amalgamated channels represent times of dominant alluvial sedimentation within the studied area. Their source is likely to the southwest, related to short periods of tectonic uplift and relative sea level falls.

The southerly directed distributaries are excellent potential stratigraphic hydrocarbon reservoirs, because they form isolated sandbodies, parallel to anticlinal crests. Shallow shot-holes and 3D seismic have confirmed the existence of such stratigraphic traps.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas