Publications

The Mahakam delta area, located in East Kalimantan, is one of the most prolific for hydrocarbons in Indonesia.Oil and gas fields are located in MioPliocene sands deposited in a deltaic environment from upper delta plain to prodelta. Shales, organic shales and coal are also interbedded in the series.Geochemical study of these series shows that they contain a high percentage of organic material. This material, though predominantly of a vegetal type, has a rather good source potential fbr gas and oil. From the data presently available, it appears that maturity of the organic material is approximately constant at a given stratigraphic level and thus the onset of the oil window is shallower at anticlines than at synclines.The oils coming from the different reservoirs in the Handil field, whatever their depth, have a similar composition contrary to the usual case of multilayer reservoir fields. The shallower a reservoir is, the lighter the oil it contains. These oils are generated from one constant type of organic matter.Studies based on carbon isotope and biological markers show that most of the oil is presently found above the ",oil-mature zone",.All these facts indicate that there was an upward migration of oil above its zone of generation and that the lighter the compounds, the further their migration.In the Mahakam Delta the distribution of oil and gas fields primarily depends on the kinetics of hydrocarbon expulsion from the source-rock. This kinetic is governed by the relative positions of the hydrocarbon generation zone and the over-pressured zone.