Publications

Kalimantan lies on the eastern margin of Sundaland, the southern extension of the Eurasian Plate. The Kutei Basin occupies the southern half of Eastern Kalimantan Province and extends offshore beneath the western shelf of the Makassar Straits. Cretaceous basement fabrics underlying the basin are oriented NW-SE and NE-SW, and these strongly influence later basin extension and inversion (Cloke et al. 1997). Starting in the Middle Miocene, sedimentation was dominated by a delta system similar to the modern Mahakam Delta (Stuart et al., 1995). This type of delta formed under conditions of very low wave energy, relatively high tides and strong fluvial regime (Allen et al., 1976), and characterized by a lack of fluvial floods (Allen et al., 1979). Nilam Field is located in the east-central Kutei Basin, beneath coastal marshes of the modern Mahakam Delta. Oil and gas fields in the Nilam area produce from intervals in the Lower Middle Miocene to Upper Miocene section. On a local scale, the structure over the study area consists of two gently folded and fairly symmetrical anticlines, elongated in a N-S direction and separated by a saddle. Vertical closure observed on seismic sections increases with depth, demonstrating syn-sedimentary structural growth. The objectives of this study were to: (1) understand the nature of the cyclic sediment stacking patterns at various scales in the Middle Miocene fluvio-deltaic reservoirs in Nilam gas field, then (2) resolve the controlling sedimentary processes, and finally (3) determine the effect of those patterns on sandstone facies and geometry.