Abstract:

The study area is located in the northern part of Song Hong basin, having complicated geological structure and depositional environment. The area has been proved to have high hydrocarbon potential by many discoveries in the fractured carbonate basement and Oligocene - Miocene sandstones. Tectonically, the area was experienced deformation and was subjected of structure interfering and overlapping between Song Hong strike-slip fault system in the northwest and northeast-southwest fault system in the northeast. In late Oligocene, the northeast part of the basin (Bach Long Vi zone) had been strongly uplifted and truncated. This formed a regional unconformity at the end of late Oligocene – early Miocene, resulting in the absence of almost early to middle Miocene sediments. However, the northwest of study area (central zone) was experienced transtensional tectonics and related to opening of the East Sea, resulting in thickening of Oligocene sediments, extending from the northwest and gradually increasing thickness to the southeast. In the early stage of rifting, the Oligocene sequence was deposited in a quite widespread lacustrine setting that provides the main potential source rock in the area. In the late Oligocene, deposition of sediments was controlled by marginal to shallow marine environment with the main sediment supply from the Red River system in the northwest that possibly creates a good reservoir potential for the study area.