Petrological and Biostratigraphic Characteristics of Pre-Cenozoic Carbonate Rocks in the Northern Song Hong Basin, Vietnam

Pre-Cenozoic carbonate rocks in the northern Song Hong basin, Vietnam that are being considered and studied by oil companies in exploration and exploitation. The hydrocarbon accumulations in these rocks have been discovered and have significantly commercial reserves, in which the porosity plays an important role in estimating the capacity of hydrocarbon. The carbonate rocks are composed mainly of crystalline limestone, packstone, wackestone and mudstone, which have been experienced dolomitization, compaction and dissolution. The main carbonate pore systems include fracture, vuggy and intercrystalline porosity. The predominance of larger benthic foraminiferal assemblages indicates that the carbonate sediments were formed during the late Paleozoic (Carboniferous-Permian) and were deposited in shallow marine environment. Furthermore, the obtained petrological and biostratigraphic characteristics are well-correlated with the carbonate formations exposed in adjacent Cat Ba island area. The results of this study are either used in petroleum exploration or used in a local stratigraphic correlation in northern Vietnam.