Using petrography and provenance to resolve reservoir characteristics of Oligocene sandstones, northern Song Hong Basin

The reservoir quality and distribution of the Oligocene sediments in the northern Song Hong Basin are refined in this study by integrating petrographic investigation with provenance analysis of the sandstones. For this purpose, the results are evaluated in context of the rift phases that affected the northern Song Hong Basin at the time. Seismic data and exploration well data were interpreted to enable the identification of depositional environments and division of the succession into early, peak and late rift phases. The stratigraphic development in sediment dispersal was studied, which is highly relevant in this prospective basin from which oil-prone source rocks have been reported locally. The probably sediment transport routes in the basin during the Oligocene have been identified by combining petrography and provenance evidence. The sediment contributions from intra-basinal highs have controlled the sediment distribution locally since the results show that not all parts of the basin were connected to the same depositional system and the sediment dispersal pattern changed in the different rift phases. These finding are important for the exploration potential since the formation of deep-lacustrine source rocks have been possible in some areas without input of coarse clastic material.