Hydrocarbon-Generating Potential of Eocene Source Rocks in the Abakaliki Fold Belt, Nigeria / Potencial za nastanek oglikovodikov v eocenskih izvornih kamninah nariva Abakaliki Cover

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Hydrocarbon-Generating Potential of Eocene Source Rocks in the Abakaliki Fold Belt, Nigeria / Potencial za nastanek oglikovodikov v eocenskih izvornih kamninah nariva Abakaliki

Materials and Geoenvironment

Volume 66 (2019): Issue 4 (December 2019)

By: O.A. Oluwajana, A.O. Opatola, O.B. Ogbe and T.D. Johnson

Open Access

|Jul 2020

Figures & Tables

Location of the study area showing the position of the Ihuo-1 well and other wells in the Abakaliki Fold Belt and the Calabar Flank. Insert: Map of Nigeria showing the location of the Abakaliki Fold Belt (marked by a red box), Southeastern Nigeria.

A simplified regional section of the Cretaceous and Cenozoic stratigraphy of Anambra Basin, Abakaliki Fold Belt and Calabar Flank, with time stratigraphy and tectonic events [9–10].

Lithostratigraphy of Ihuo-1 well showing the different sedimentary intervals with relative ages. Note the gaps within the litholog, representing unconformity.

Cross-plot of S1 against TOC for the Eocene source rocks in Ihuo-1 well [16], used in distinguishing the hydrocarbon (potential) types. The red dots indicate the analysed samples.

Cross-plot of generation potential (GP) against total organic content (TOC) of Eocene source rocks in Ihuo-1 well [16], used to know the source potential of the sediment. The red dots represent the analysed samples.

Van Krevelen diagram for kerogen typing of Eocene shale samples in Ihuo-1 well [16], used to determine the kerogen types of the shale samples. The red dots represent the analysed samples.

Pseudo-Van Krevelen diagram of Eocene shale samples in Ihuo-1 well [20], used to determine the kerogen types of the shale samples. The red dots represent the analysed samples.

Boundary condition used to model the most probable scenario for hydrocarbon generation in the Abakaliki Fold Belt. The figure indicates the heat flow trend for the Lower Eocene source rock.

Correlation of measured and modelled vitrinite reflectance data for Ihuo-1 well. The heat flow values were determined based on the tectonic history of the basins and were defined by streaming modelled and measured thermal data.

One-dimensional history of the buried Eocene source unit in Ihuo-1 well extracted from the model. The coloured model indicates the modelled vitrinite reflectance maturity overlay.

Burial history of the Ihuo-1 well showing the transformation ratio overlay for the deeply buried Eocene source unit.

Geochemical results of rock-eval/TOC analyses of Eocene samples in Ihuo-1 well

Depth (m)	TOC (wt.%)	Rock-eval pyrolysis
Depth (m)	TOC (wt.%)	S₁ (mgHC/gTOC)	S₂ (mgHC/gTOC)	S₁ + S₂	T_max	OI (mgHC/gTOC)	HI (mgHC/gTOC)	PI (mgHC/gTOC)
2204	0.8	2.7	2.58	5.28	442	171	323	0.51
2265	1.8	3.91	2.88	6.79	441	158	160	0.58
2320	1.5	3.70	2.40	6.10	439	156	150	0.61
2355	0.8	2.56	1.45	4.01	466	129	181	0.64
2375	0.7	6.52	3.28	9.80	455	557	469	0.67
2415	1.1	4.14	2.03	6.17	476	177	185	0.67
2510	0.9	1.60	0.83	2.43	469	17	92	0.66
2520	1.0	5.03	2.18	7.21	478	353	218	0.7
2557	0.8	2.53	1.21	3.74	480	116	151	0.88

Input for 1D basin modelling of the Ihuo-1 well as used in the present study_

Layer name	Depth range (m)	Thickness (m)	Deposition period (Ma)	Erosion period (Ma)	Modelled TOC (wt.%)	Modelled HI (gHC/gTOC)
Overburden	0–28	28	0.2–0
Mio-Oligocene (Coastal plain sands)	28–584	556	27–0.2
Oligocene shaly sands	584–1328	744	28–27
Upper Eocene (Bende/Ameki Formation)	1328–1426	98	37.6–34	34–28
Mid-Eocene (Bende/Ameki Formation)	1426–1862	436	41.2–39	39–37.6
Lower Eocene (Bende/Ameki Formation)	1862–2655	793	49–41.2		1	214
Lower Eocene (Bende/Ameki Formation)	2655–2710	55	54–49
Lower Eocene (Bende/Ameki Formation)	2710–2863	153	56–54
Palaeocene (Imo Shale)	2863–3228	365	66–56
Maastrichtian (Nkporo Shale)	3228–3450	222	71.2–66

Measured vitrinite reflectance values of Eocene stratigraphic levels in Ihuo-1 well_

Well	Depth (m)	Vitrinite reflectance values
Ihuo-1	2204	0.80
Ihuo-1	2265	0.78
Ihuo-1	2375	1.03
Ihuo-1	2557	1.48

DOI: https://doi.org/10.2478/rmzmag-2019-0014 | Journal eISSN: 1854-7400

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Language: English

Page range: 223 - 233

Submitted on: Sep 28, 2019

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Accepted on: Nov 22, 2019

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Published on: Jul 25, 2020

Published by: Sciendo

In partnership with: Paradigm Publishing Services

Publication frequency: 4 issues per year

Keywords:

Abakaliki Fold Belt,

basin modelling,

Related subjects:

Computer sciences,

Databases and data mining,

Geology and mineralogy,

Materials sciences,

Materials characterization and properties

© 2020 O.A. Oluwajana, A.O. Opatola, O.B. Ogbe, T.D. Johnson, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

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