Hydrocarbon Potential and Biomarker Studies of EE-1 Well, Offshore Eastern Dahomey Basin, SW Nigeria

Matthew E. Nton; Emeka E. Emordi; Irewole Ayodele

doi:10.2478/rmzmag-2021-0011

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Hydrocarbon Potential and Biomarker Studies of EE-1 Well, Offshore Eastern Dahomey Basin, SW Nigeria

Materials and Geoenvironment

Volume 69 (2022): Issue 1 (June 2022)

By: Matthew E. Nton, Emeka E. Emordi and Irewole Ayodele

Open Access

|Sep 2023

Figures & Tables

*Regional map of four countries showing the location of the Benin (Dahomey) Basin in the Gulf of Guinea [11].*

*Dahomey embayment showing the study area (after d’Almeida et al. [14]).*

*Lithological log of the studied section of EE-1 Well*.

Table 1:

Results of TOC and Rock-Eval Pyrolysis of the studied samples.

Sample ID	Depth (m)	SOM (ppm)	TOC	S1	S2	S3	T_max	Calc. %Ro	GP (S1 + S2)	HI	OI	SOM/TOC	S1/TOC	PI
S1	1240	676.12	1.14	0.13	1.11	2.23	423	0.45	1.24	97	196	59.31	11	0.10
S2	1340	2004.31	1.01	0.16	1.02	2.36	422	0.44	1.18	101	234	198.45	16	0.14
S3	1410	ND	1.19	0.16	1.31	2.78	425	0.49	1.47	110	234	ND	13	0.11
S4	1480	1417.71	1.41	0.19	1.93	2.55	428	0.54	2.12	137	181	100.55	13	0.09
S5	1560	ND	0.96	0.15	1.15	2.51	429	0.56	1.3	120	262	ND	16	0.12
S6	1620	2456.23	0.97	0.15	1.26	1.96	429	0.56	1.41	131	203	43.03	16	0.11
S7	1700	2883.85	1.02	0.21	1.66	2.79	427	0.53	1.87	163	274	13.04	21	0.11
S8	1760	1835.19	1.47	0.25	2.60	2.39	430	0.58	2.85	177	163	15.28	17	0.09
S9	1830	1599.37	1.94	0.34	5.84	2.51	426	0.51	6.18	301	129	11.96	18	0.06
S10	1906	1205.55	2.63	0.93	8.24	2.53	427	0.53	9.17	313	96	6.13	35	0.10
S11	1965	2698.84	1.91	1.00	4.11	2.51	431	0.60	5.11	215	131	23.64	52	0.20
S12	2040	1826.01	2.03	0.95	2.99	3.29	425	0.49	3.94	147	162	6.28	47	0.24
S13	2118	ND	1.18	0.39	2.94	2.30	429	0.56	3.33	249	195	ND	33	0.12
S14	2180	2143.91	1.15	0.63	3.25	2.79	422	0.44	3.88	283	243	186.43	55	0.16
S15	2257.5	1978.45	8.92	1.35	43.18	3.15	426	0.51	44.53	484	35	22.18	15	0.03

1 TOC = weight percent organic carbon in rock, GP = petroleum genetic potential

T_max = °C, HI = hydrogen index

S₁+S₂ = mg HC/g of rock, OI = oxygen index

S₃ = mg CO₂/g of rock, PI = production index = S1 / (S1+S2)

S₁/TOC = normalized oil content, Calc. % Ro = Calculated vitrinite reflectance

SOM = Soluble Organic Matter, ND = Not done

*A cross plot of hydrogen index (HI) versus oxygen index (OI) showing that the organic matter of the studied well is of types II and type III kerogen (Modified after Van Krevelen [29])*.

*A cross plot of remaining hydrocarbon potential (S2) against total organic content (TOC) showing the organic matter type and origin (after Jackson et al. [30]).*

*Plot of hydrogen index (HI) against T_max showing that the kerogen is in the immature window [33]*.

*Total ion chromatograms showing the distribution of the saturated hydrocarbon fraction of representative Samples 4B and 6B from the study well*.

Table 2:

Data showing values of isoprenoids, isoprenoids/n-alkane ratios and other parameters for EE-1 well.

Sample ID	Pr/Ph	Pr/n-C₁₇	Ph/n-C₁₈	CPI	OEP-1	OEP-2
1B	1.47	0.98	0.62	1.93	0.51	0.83
2B	1.74	1.20	0.90	1.66	0.45	0.76
4B	2.38	2.41	1.08	1.70	0.51	0.8
6B	2.05	2.99	1.83	1.51	0.46	0.62
7B	3.20	2.42	1.40	1.67	0.53	0.7
8B	2.33	1.58	0.76	1.23	0.39	0.51
9B	1.49	2.31	1.55	1.27	0.47	0.49
10B	1.78	1.24	0.63	1.01	0.35	0.41
11B	2.20	0.99	0.51	1.12	0.39	0.44
12B	1.65	0.92	0.54	1.04	0.37	0.4
14B	1.94	0.60	0.46	0.37	0.4	0.08
15B	1.80	0.80	0.42	1.12	0.41	0.42

1 Abbreviations: Pr/Ph, pristane/phytane; Pr/nC₁₇, pristane/normal-C₁₇ alkane; Ph/nC₁₈, phytane/normal-C₁₈ alkane; CPI, carbon preference index, 2 (C₂₃ + C₂₅ + C₂₇ + C₂₉) / (C₂₂ + 2 C₂₄ + C₂₆ + C₂₈) + C₃₀); OEP-1, (C₂₁ + C₂₃ + C₂₅) / (4C₂₂ + 4C₂₄); OEP-2, (C₂₅ + C₂₇ + C₂₉) / (4C₂₆ + 4C₂₈); OEP, odd-to-even predominance.

*Cross plot of Pr/n-C₁₇ versus Ph/n-C₁₈ showing the sources of organic matter and the depositional environment (Modified after Cortes et al. [39])*.

*m/z 217 mass chromatograms showing the distribution of steranes and diasteranes in the selected samples 4B and 12B*.

*m/z 191 mass chromatograms showing the distribution of terpanes and hopanes in the EE-1 Well samples 4B and 12B.12B*.

Table 3:

Biomarker maturity parameters computed for the studied well samples.

Sample ID	Ts /Tm	Mor / Hop	αββ/αββ+ααα C₂₉ Sterane	22S/22S+22R	MPI-1	DMN	TMN-1	MDBT
1B	0.22	0.26	0.28	0.37	1.72	3.56	0.89	2.98
2B	0.25	0.26	0.25	0.34	1.46	2.96	0.73	3.35
4B	0.35	0.48	0.06	0.40	1.75	4.19	0.91	2.83
6B	0.32	0.29	0.21	0.38	1.37	4.04	1.13	3.11
7B	0.27	0.22	0.24	0.42	1.41	3.53	0.97	6.21
8B	0.34	0.18	0.23	0.46	1.35	2.25	1.06	1.81
9B	0.32	0.16	0.18	0.48	1.48	3.74	1.05	1.98
10B	0.35	0.14	0.30	0.57	1.12	3.01	1.17	0.82
11B	0.48	0.13	0.34	0.60	1.16	3.33	0.79	1.07
12B	0.50	0.11	0.44	0.58	1.01	3.25	0.67	1.51
14B	0.44	0.14	0.35	0.58	1.28	4.96	1.11	2.19
15B	0.45	0.10	0.42	0.59	1.32	4.36	0.79	1.47

1 Abbreviations: Ts/(Ts+Tm), trisnorneohopanes/trisnorhopanes ratio; Mor/Hop, 17β, 21α (H)Mortane/17 α, 21β (H) hopane ratio; 22S/22S+22R, 22S/22S+22R extended hopanes ratio; MPI-1 - methyl – phenanthrene index, 1,5 (2MP + 3MP) / (P + 1MP + 9MP); DMN – dimethyl naphthalene ratio, 2, 6 DMN + 2,7 DMN)/1,5 DMN; TMN-1 – trimethyl naphthalene ratio, (1,3,7 TMN)/ (1,3,7 TMN + 1,2,5 TMN); MDBT – methyl-dibenzothiopene ratio, 4MDBT/1MDBT.

Table 4:

Source and depositional environment parameters computed from the saturate biomarkers of the EE-1 well.

Sample ID	%C₂₇ Sterane	%C₂₈ Sterane	%C₂₉ Sterane	C₂₁T/C₂₃T	C₂₃T/C₂₄T	Hop/Ster	dia/reg	Ole/Hop	Gam/Hop	C₂₄ Tet/(C₂₆ (S+R) + C₂₄ Tet)	C₂₅/C₂₆ (S+R)	C₃₅/C₃₁^-C₃₅Hom
1B	33.50%	19.68%	46.82%	0.58	1.49	4.13	0.18	0.1	0.08	0.52	0.69	0.06
2B	34.79%	22.11%	43.10%	0.8	1.59	2.99	0.15	0.11	0.1	0.49	0.54	0.14
4B	27.36%	19.31%	53.33%	0.49	1.33	1.98	0.28	0.62	0.04	0.6	0.48	0.05
6B	33.10%	20.73%	46.18%	0.82	1.66	1.62	0.21	0.42	0.05	0.62	0.89	0.05
7B	33.35%	20.97%	45.68%	0.78	1.39	3.65	0.27	0.29	0.04	0.67	0.48	0.05
8B	36.81%	21.02%	42.17%	0.62	1.73	4.1	0.23	0.33	0.04	0.64	0.41	0.05
9B	36.85%	25.19%	37.96%	0.55	1.98	1.53	0.13	0.21	0.04	0.6	0.44	0.07
10B	40.18%	25.85%	33.97%	0.33	3.45	6.04	0.33	0.07	0.04	0.52	0.69	0.09
11B	38.09%	24.36%	37.55%	0.39	3.1	11.45	0.42	0.04	0.03	0.72	0.67	0.06
12B	38.86%	27.19%	33.95%	0.36	2.57	16.11	0.48	0.06	0.04	0.45	0.67	0.09
14B	36.49%	23.80%	39.71%	0.46	1.91	6.27	0.35	0.14	0.06	0.5	0.56	0.11
15B	37.53%	41.63%	45.42%	0.37	1.92	6.91	0.38	0.08	0.09	0.45	0.63	0.17

1 Abbreviations: Ole/Hop, oleanane index; Hop/Ster, hopane/sterane ratio; dia/reg, diasterane index; Gam/Hop, gammacerane index; C₃₅/C₃₁-C₃₅ Hom, homohopane index; C₂₅/C₂₆(S+R), C₂₅/C₂₆(S+R) trycyclic terpane ratio; C₂₄ Tet / (C₂₆ (S+R) + C₂₄ Tet), tetracyclic terpane ratio.

*Ternary plot showing distribution of C₂₇, C₈ and C₉ steranes for EE-1 Well. (After Huang and Meinschein [49])*.

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DOI: https://doi.org/10.2478/rmzmag-2021-0011 | Journal eISSN: 1854-7400

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Language: English, Slovenian

Page range: 33 - 46

Submitted on: Jul 2, 2021

Accepted on: Jan 18, 2022

Published on: Sep 4, 2023

Published by: Sciendo

In partnership with: Paradigm Publishing Services

Publication frequency: 4 issues per year

Keywords:

hydrocarbon potential,

biomarker,

Dahomey Basin

Related subjects:

Computer sciences,

Databases and data mining,

Geosciences,

Geodesy,

Geology and mineralogy,

Materials sciences,

Materials characterization and properties

© 2023 Matthew E. Nton, Emeka E. Emordi, Irewole Ayodele, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Volume 69 (2022): Issue 1 (June 2022)

Hydrocarbon Potential and Biomarker Studies of EE-1 Well, Offshore Eastern Dahomey Basin, SW Nigeria

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