Biostratigraphic characteristics and correction of the boundary between Miocene and Oligocene sediments in the northern Malay - Tho Chu basin

Stratigraphic study in oil and gas wells is dependent on the research method and the characteristics of the collected samples, such as sample types and spaces between samples, that is why the stratigraphic boundary of the wells may fluctuate in a certain sedimentary range. Therefore, when re-evaluating the hydrocarbon potential or expanding the petroleum exploration targets of an area, we need to study additional evidence and geological events to correct the stratigraphic boundary of the well and correlate regional stratigraphy. These studies often use biostratigraphic and seismic stratigraphic methods. This paper provides evidence on biostratigraphy to correct the stratigraphic boundary between Miocene and Oligocene sediments in the northern Malay - Tho Chu basin and compares them with the general stratigraphy of the Malay basin. The research results determined that the top of the Oligocene sediment after correcting is higher than what was specified in the previous studies based on marker fossil findings in a palynomorph abundance cycle; and there are similar biostratigraphic characteristics between the studied area and the Malay basin.