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ABSTRACT: Reservoir architecture of a distributary channel-fill complex from the Middle Miocene Kutai Basin, Indonesia

Sidi, F. Hasan1, A. Setiawan1, and P. J. Butterworth2
(1) VICO Indonesia, Jakarta, Indonesia
(2) ARCO British Ltd, London, England

The Middle Miocene deltaic reservoirs of the Kutai Basin of East Kalimantan are one of the most prolific hydrocarbon provinces of S.E Asia. The recent acquisition of a land-transition 3D-seismic survey over the relatively mature Nilam Field has greatly enhanced the understanding of the three dimensional architecture of the reservoirs.

An example is the Nilam G053B reservoir, which is located more than 3.5 km in depth around the saddle of Nilam anticline. The G053B sand has been penetrated by more than 50 wells and produced more than 100 BCF of gas to date. Well log correlation indicates a relatively low aspect ratio, comprising a channel belt with a width of 2-3 km and a channel-fill thickness of up to 36 meters. The interpretation of conventional cores is of a heterogeneous facies assemblage documenting the initial fill and subsequent transgressive reworking within a lower delta plain environment.

The integration of 3D seismic and a detailed geological study has allowed an in-depth re-evaluation of the internal architecture of channel-fill complexes. The ability to be able to delineate channel thalweg and fluvial point bar complexes has allowed a robust geological interpretation of the complex inter-relationship between the net-pay, porosity and permeability distribution. Stacking patterns suggest that the clustered channel complex was formed during a major regressive phase as an incised valley fill.

Understanding the scale of the internal heterogeneity has reduced the risk on targeting the better permeable zones with horizontal wells, and will add significantly to the deliverability of this mature field.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia