Publications

The “S” Field in the Anambas structure of the West Natuna Basin offers a diverse geological framework, containing gas and condensate within multiple Eocene to Miocene dated reservoir packages. Geochemical fingerprint and PVT (Pressure-Volume-Temperature) analysis conducted on gas samples from the ANB-2X well have successfully identified two distinct types of gas with unique origins and implications for exploration which are thermogenic and biogenic.

The thermogenic gas is interpreted to be sourced by Eocene–Oligocene dated source rocks with a mix of terrestrial and marine kerogen (organofacies D/E), this responsibles for hydrocarbon accumulations in Eocene–Oligocene intervals including Lama, Lower Gabus, Keras, and Upper Gabus Formations. Notably, deeper sections in these intervals also contain heavier hydrocarbons. In contrast, biogenic gas, primarily produced through microbial activity in cooler temperature domain, less pressurized shallower Miocene rocks, charging the gas in the Arang Formations.

The identification of these distinct gas types has significant implications for exploration and development in the West Natuna Basin, particularly regarding shallow gas accumulations. It provides insights into the hydrocarbon systems at play, offering a clearer understanding of the risks and potential rewards in targeting both shallow biogenic gas and deeper thermogenic gas. This knowledge enables more effective exploration strategies and better management of hydrocarbon resources to fulfill company needs.