Abstract

Deposition of carbonates in the Northwest Java Basin occurred at four different stratigraphic levels during the Tertiary.

Widepsread carbonate deposition occurred during Oligocene-lower Miocene and late middle Miocene time intervals, while more localized deposition occurred during two intervals within the lower to middle Miocene.

During each of these times associated carbonate build-ups were developed which can be recognized and mapped in detail from the excellent seismic data in the area.

The size, shape and disposition of all build-ups, except those developed during late middle Miocene, is shown to be related to the tectonic framework, depositional history and local structural features of the basin. The late middle Miocene build-ups appear to be unrelated to palaeo-structural features, indicating deposition on a base-levelled surface at a time of structural maturity and quiescence.

The ability of the seismic data to indicate variations in porosity and to detect both direct and indirect indications of hydrocarbons within the build-ups is illustrated. An excellent example is shown in which the presence of a large volume of gas within a late middle Miocene carbonate build-up can be interpreted directly from the seismic data.