Publications

Three major tectonic elements are recognized during Early Oligocene in the Natuna area, i.e. the West Natuna Basin, the East Natuna Basin and the Natuna Arch. The arch represents a N-S trending basement high which effectively separates the two basins.Basin development in West Natuna started during Early Oligocene where rifting and/or pull-apart produced predominantly SW-NE halfgrabens filled with nonmarine sediments. The features probably formed due to the extrusion of the Malay Peninsula from Asia during the early stages of the India-Asia conision. T& 'tensional forces of West Natuna however seemed to have little effect on the East Natuna Basin where Oligocene sediments are uniformly represented and thicken only regionally eastward toward the basin Center.Compressive forces began to dominate in the West Natuna basin during Early Miocene, resulting in reverse movement of once normal faults and corresponding uplift of areas which previously were half grabens. During this same time East Natuna was structured by predominantly tensio d forces which prclduced NW-SE right lateral movements coupled with SW-NE normal faulting. The differences in tectonic regimes between West and East Natuna during Early Miocene can again be explained by a changing pattern in the extrusion of Indochina from Asia during later stages of India's collision with Asia.The hydrocarbon potential of the West Natuna Basin is heightened by the presence ?f local thick sequences for both Oligocene and Miocene sediments which were tectonically controlled. Both sections offer good potential for source and reservoir rocks. In the West part of the East Natuna Basin the presence of thick, mature sediments is limited to areas of Early Miocene grabens.