Oil charge history of Paleogene–Eocene reservoir in the Termit Basin (Niger)

Abstract

A total of 73 oils from the sandstone reservoir of Paleocene–Eocene Sokor 1 Formation in the Termit Basin (eastern Niger) were analysed to investigate the distribution characteristics of biomarkers. Most of the oil samples are quite similar in their organic geochemical characteristics and should have been derived from the same source bed/source kitchen. The homogenisation temperatures of aqueous inclusions in Paleocene–Eocene reservoir of the Termit Basin vary with a range of 76–125 °C. By combining the homogenisation temperatures with the burial and geothermal histories reconstructed by 1-dimensional basin modelling, the timing and episode of oil charge can be obtained, i.e. 13 to 0 Ma for Paleocene–Eocene reservoirs in the Termit Basin. Two presentative geochemical parameters, i.e. Ts / (Ts + Tm) and 2,4-dibenzothiophene/1,4-dibenzothiophene (2,4-DMDBT/1,4-DMDBT) were applied to trace the oil migration direction and filling pathway. The preferred oil-filling points in the northwest section of the Termit Basin were determined, and the promising exploratory targets were proposed for further oil exploration in this region.

Keywords:

• oil family classification
• oil charge timing
• oil migration orientation
• oil-filling pathway
• Termit Basin
• Niger

Acknowledgements

The authors are grateful for the assistance of Shengbao Shi and Lei Zhu for the geochemical analyses of all selected samples. We would like to thank the Research Institute of Petroleum Exploration and Development, PetroChina for permission to publish this work. The authors extend their appreciation to Dr Liu and two anonymous reviewers for their valuable comments and suggestions that significantly improved this paper.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was sponsored by National Key Project (2016ZX05029).