Biostratigraphic and petrological characteristics of Cretaceous\u2013Paleogene sediments in the eastern Cuu Long delta

Mai Hoang Dam,Vu Thi Tuyen,Nguyen Tan Trieu,Nguyen Thi Tham

doi:10.1007/s13202-021-01156-8

Mai Hoang Dam, Vu Thi Tuyen + Show 2 more

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https://doi.org/10.1007/s13202-021-01156-8

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Abstract

The basic structure of reservoir models is strongly affected by the stratigraphic interpretation and the properties of reservoir rock. The estimation of the volume of hydrocarbon accumulation will depend on the accuracy of predicting and distributing reservoir quality. Biostratigraphic and sedimentary petrologic results provide geological information to clarify the stratigraphy and properties of sedimentary rocks on the eastern margin of the Cuu Long delta plain trough. On the basis of stratigraphic correlation of the wells and studying the structures of the area, the deposition, thickness of sediments and the ability to correlate with prospect rocks on the southeastern Vietnam continental shelf were determined. The results have identified the basement rock of wells TC-1 and TC-2, which are Cretaceous metasandstones and were deposited in freshwater fluvial environments with high-energy conditions. The upper Paleogene sediments were overlaid directly on the Cretaceous basement rock in the TC-2 well but were completely absent in the TC-1 well. The lithologic composition is mainly feldspathic litharenite sandstone, which is formed in freshwater fluvial and freshwater lacustrine environments. This study provides new data on stratigraphic column of the eastern Cuu Long delta plain. The data show that the age of the sedimentary basement rock is Cretaceous which has not been determined in previous studies. The findings of this study can help for better understanding of the geological development history and the completely stratigraphic column of the Cuu Long delta to correlate with objects that are hydrocarbon accumulation in Cuu Long sedimentary basin in order to improve efficiency in petroleum exploration activities.

Highlights

In the early 1980s, petroleum exploration in southern Vietnam was promoted both on the continental shelf and mainland in the Cuu Long delta
The age of Cretaceous sediment of the TC-1 and TC-2 wells was identified by palynology assemblages
Reticuloidosporites arcus and Sestrosporites spp. (Fig. 4). These spore assemblages have been found in freshwater sediments and commonly occur in Cretaceous sediments, which are well known in southern Vietnam (Wantoro et al 2005; Quang 2005, 2006), Malaysia (Muller 1968) and Australia (Helby et al 1987; Burger 1996)

Summary

Introduction

In the early 1980s, petroleum exploration in southern Vietnam was promoted both on the continental shelf and mainland in the Cuu Long delta. Paleontological and petrographic studies aimed at detailing borehole stratigraphic columns to clarify the geological structure of the area. These results have allowed the determination of the existence, characteristics and thickness of sediments and their relation to sedimentary basins that contain petroleum offshore of the continental shelf to assess and forecast the oil and gas prospects in the Cuu Long delta. The results of the study show that palynomorph assemblages are found to be relatively abundant and are characteristic of the Cretaceous period and mainly deposited in the freshwater fluvial settings This is an interesting finding of this study.

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