Sedimentary facies and grain size distribution; Insights into Ogwashi-Asaba Formation, Niger Delta Basin

Eghele Akpere * and Anthonia N. Asadu

Department of Earth Sciences, Federal University of Petroleum Resources, Effurun 330102, Delta State, Nigeria.
 
Research Article
International Journal of Science and Research Archive, 2024, 13(02), 2769–2778.
Article DOI: 10.30574/ijsra.2024.13.2.2464
Publication history: 
Received on 02 November 2024; revised on 11 December 2024; accepted on 13 December 2024
 
Abstract: 
The Niger Delta is renowned for being one of the most productive hydrocarbon provinces globally. This productivity is primarily attributed to its complex geological history, which is marked by intricate stratigraphy and various sedimentary facies. These sedimentary facies, which are distinct bodies of sediment with specific characteristics, provide essential information about past environments and sedimentary processes, about the complex stratigraphy and diverse sedimentary facies. Stratigraphic sequences in the Niger Delta include alternating layers of sandstones, shales, and siltstones. Sediment samples were collected with cores too, from the Ogwashi-Asaba formation, and a detailed field analysis was documented. Grain size, petrographic, and geochemical analysis were carried out in the lab, from the samples collected. The analyzed parameters suggest that the sandstone samples from the Ogwashi-Asaba Formation are predominantly fluviatile. Graphic Mean (Mz) ranges from 1.4 to 2.1 phi. Grain Size Composition 2-20% very fine sand, 6-66% fine sand, 45-87% medium to coarse sand, and 70-100% very coarse sand. Sorting (σ1) ranges from 1.1 to 2.1 phi, with 64.71% of sediments being very poorly sorted and 35.29% poorly sorted. Graphic Skewness (Sk) ranges from -0.6 to +0.5, indicating varying energy conditions. Graphic Kurtosis (KG): Ranges from 0.8 to 1.9, with curves varying from leptokurtic to platykurtic. These sedimentary processes shaping the Ogwashi-Asaba formation creates a diverse stratigraphy and a variety of sedimentary facies. Each provides valuable insights into past environmental conditions and sedimentary dynamics. A comprehensive understanding of these processes enhances the potential for hydrocarbon exploration and the reservoir characterization of the province.
 
Keywords: 
Facies; Sequences; Niger Delta; Ogwashi-Asaba; Formation
 
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