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Map showing the extent of the Bass Basin, highlighting the studied wells (modified after Boreham et al. 2003)
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This research aims to conduct source rock characterization on the Narimba Formation in the Bass Basin, Australia, which is made of mostly sandstone, shale and coal. The geochemical characteristics and depositional environments have been investigated through a variety of data such as rock–eval pyrolysis, TOC, organic petrography and biomarkers. Tota...
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This study was conducted to obtain the characteristics of the source rock through organic geochemical analysis in Central Deep, NE Java Basin, in the field off the north coast of Madura. Three samples of Cassiopeia-1, Pollen-1, and Alpha-1 wells were analyzed using organic geochemical methods including Total Organic Carbon analysis, Maturity using...
Citations
... The Agbada Formation overlies the Akata shale (Fig. 9b), deposited in a paralic depositional setting (transitional environment: mixed continental, brackish water, and shallow marine deposit). It is characterized by type II/III and III kerogen (Martínez et al., 2008;Shalaby et al., 2020). Substantial quantities of type III kerogen present in the Agbada Formation were transported from the adjacent delta plain environment into a marginal paralic setting (Cobbold et al., 2009) and incorporated into paralic sediments (Lin et al., 2020;Abidin et al., 2022). ...
The pattern of Eocene Niger Delta source rock organic matter occurrence, distribution, and maturity in a well located in the northwestern depobelt of the Niger Delta is investigated to characterize the hydrocarbon source potential in this part of the delta. A total of 51 core and 45 non-composited ditch-cutting shale samples were subjected to total organic carbon (TOC) analysis and Rock–Eval pyrolysis. Primary and derived data show good–excellent generation potential. Cross plots of hydrogen index (HI) versus TOC were used to classify kerogen types as II, II/III, and III, which exhibited stratigraphic variation. Tmax and vitrinite equivalent (Requ) indicate early-peak maturity, contrary to views that maturation was not possible above depths of 2500 m. The production index (PI) indicated thermal conversion with depth. The distribution pattern of type II kerogen in the immature zone and types II/III and III in the mature zone appears anomalous. While it suggests and favors the effect of hydrocarbon generation and expulsion (fractional conversion, f = 48.25–68.19%) and stratigraphic variability as a probable cause of observed kerogen types variability and Tmax trend between the immature and mature zones, stratigraphic wedging at the Akata and Agbada Formations interface/transition zone, it may not be discounted as a probable cause of the observed anomaly. The result of this study adds to the range of answers advanced in resolving the age-long controversies on the actual source sediments of hydrocarbon resources in this part of the Niger Delta Basin and other similar settings.
Graphical abstract
... Vitrinite reflectance (% VR) is the measurement of the coalification degree where light is reflected on a polished surface according to different maturity level (Mukhopadhyay and Hatcher, 1993;Law, 1999;Wilkins and George, 2002;Shalaby et al., 2020). % VR data shown in Table 2 for 77 source rock samples were collected from five wells and were used as maturity indicator in this study -Kipper-1, Kipper-2, Basker-1, Tuna-1 and Tuna-4 wells (68 samples from Chimaera Formation, 2 samples from Curlip Formation, and 7 samples from Kipper Shale). ...
... Biomarkers are molecular fossils that can be found in oil, rocks and sediments. They have high resistance against degradation and retain most of its original skeleton after the organisms died (Simoneit, 2002;Mobarakabad et al., 2011;Shalaby et al., 2020). In addition, they are globally available making them useful for source rock studies. ...
... Most source rock samples with type III (gas prone) kerogen are in the mature stage while majority of the coal samples have been shown to be in the immature stage (Fig. 10). PI is the portion of free hydrocarbon (bitumen) to the total amount hydrocarbon (bitumen and kerogen) (Tissot and Welte, 1978;Peters and Cassa, 1994;Shalaby et al., 2020). Cross-plot of Tmax vs PI in Fig. 11 shows that the source rock samples are mostly mature with minority being in immature stage. ...
... The distribution of steranes is best studied on GC/MS by monitoring the ion m/z 217 which are a class of saturated polycyclic hydrocarbons found in crude oils and are obtained from sterols of ancient organisms. The regular sterane biomarkers C 27 , C 28 , and C 29 (Table 2) appear as 20S and 20R epimer and can also be used as a measure of either the depositional environment of the organic matter amounting to the hydrocarbon or established relationship between oils (e.g., Ahmed et al., 2022;Shalaby et al., 2020). ...
... The distribution of n-alkanes can aid in identifying the depositional environment of source rock samples (e.g., Chen et al., 2022;Shalaby et al., 2020). Pristane (Pr) and phytane (Ph) are present in lower amplitude than those of the adjacent n-alkanes (nC17 and nC18) in some of the samples (YOS1 and IOS), resulting in Pr/ nC17and Ph/nC18 ratios <1.0, respectively ( Table 2). ...
prospective source rocks (shales) of the Bima Formation in the Gongola sub-basin, Northern Benue Trough, Nigeria, were studied in the field and laboratory to increase our understanding on their hydrocarbon-generating potential, thermal maturity, and
paleo-depositional environment. Results obtained from the field studies suggest that the Bima Formation was deposited in a fluvial setting owing to the absence of marine fossils and presence of ferruginized beds. Other attributes of the fluvial settings observed include mud cracks and poor sorting, implying textural immaturity. Results of the geochemical analysis obtained show that the studied shales are rich in organic matter and inferred to have mostly kerogen type II–III and type III, which may be able to yield mixed oil and gas and gas, respectively. The trisnorhopane thermal maturity (trisnorneohopane/trisnorhopane) values of the studied shales vary between 0.88 and 1.12, implying that the studied shales are within the oil window. Also, cross-plot of C29 steranes epimer ratios versus C32 homopopanes epimer ratios range from 0.46 to 0.48, suggesting that all the source rocks are thermally mature. The Pr/n-C17 versus Ph/n-C18 cross-plot and the steranes ternary plot revealed that oil extracted from the studied shale samples originated from organic matter of both marine and terrestrial sources (mixed organic matter) and was deposited under anoxic and suboxic conditions.
... The type of organic matter present in source rocks determines the quality, and kerogen composition determines the petroleum potential. Organic matter quality refers to whether organic matter is suitable to generate either oil, gas, or both [1] and [21]. Rock-Eval pyrolysis S2 and S3 data were used to characterize the organic matter type (kerogen type). ...
Total organic carbon and Rock – Eval pyrolysis studies were conducted on seven (7) shale samples outcropping in parts of Ini Local Government Area of Akwa Ibom State, Southeastern Niger Delta, Nigeria. The studies were done to determine the quantity and quality of organic matter in the shale source rock, and their hydrocarbon generation potential. Total organic carbon (TOC) values indicate poor to excellent organic richness with values ranging from 0.46 wt.% to 5.98 wt.%. The free oil content (S1) values range from 0.02-0.21 mg HC/g rock, (mean = 0.07 mg HC/g rock), while the source rock potential (S2) ranges from 0.08-1.09 mg HC/g rock with an average value of 0.45 mg HC/g rock both indicating poor source rock generative potential. The Hydrogen Index (HI) and the Oxygen Index (OI) range from 11 mg HC/g TOC to 59 mg HC/g TOC and 41 mg CO/g TOC to 74 mg CO/g TOC with an average value of 27.28 mg HC/g TOC and 55.71 mg CO/g TOC respectively. HI versus OI and S2 versus TOC cross plot results indicate that shale in parts of Ini Local Government Area contains organic matter capable of generating kerogen type III to type 1V which is gas prone.
... The type of organic matter present in source rocks determines the quality, and kerogen composition determines the petroleum potential. Organic matter quality refers to whether organic matter is suitable to generate either oil, gas, or both [1] and [21]. Rock-Eval pyrolysis S2 and S3 data were used to characterize the organic matter type (kerogen type). ...
Total organic carbon and Rock – Eval pyrolysis studies were conducted on seven (7) shale samples outcropping in parts of Ini Local Government Area of Akwa Ibom State, Southeastern Niger Delta, Nigeria. The studies were done to determine the quantity and quality of organic matter in the shale source rock, and their hydrocarbon generation potential. Total organic carbon (TOC) values indicate poor to excellent organic richness with values ranging from 0.46 wt.% to 5.98 wt.%. The free oil content (S1) values range from 0.02-0.21 mg HC/g rock, (mean = 0.07 mg HC/g rock), while the source rock potential (S2) ranges from 0.08-1.09 mg HC/g rock with an average value of 0.45 mg HC/g rock both indicating poor source rock generative potential. The Hydrogen Index (HI) and the Oxygen Index (OI) range from 11 mg HC/g TOC to 59 mg HC/g TOC and 41 mg CO/g TOC to 74 mg CO/g TOC with an average value of 27.28 mg HC/g TOC and 55.71 mg CO/g TOC respectively. HI versus OI and S2 versus TOC cross plot results indicate that shale in parts of Ini Local Government Area contains organic matter capable of generating kerogen type III to type 1V which is gas prone.
The Early to Late Miocene Belait Formation in Brunei-Muara district has been investigated using the PhaseKinetic approach for compositional petroleum generation kinetics. The source rock characteristics of the selected coal and coaly shale samples indicate kerogen type III-II and type III with moderate HI recorded in the range of 156–258 mg HC/g TOC. The Rock Eval pyrolysis data also show immature organic matter with maximum recorded Tmax values of 415 °C. Pyrolysis gas chromatography (PyGC) reflects that the source rocks generated petroleum grading from paraffinic-naphthenic-aromatic (P–N-A) high wax to gas and condensate, which can be interpreted as heterogeneous kerogen derived from terrigenous higher land plant material. The main activation energies range of two selected coal samples (S24 and S27) are located at 49–52 kcal/mol accounting each for only 15% of the total bulk reaction. Assuming a 3 °C/My geologic heating rate, calculated onset temperatures for the generated hydrocarbon at transformation ration, TR = 10% were 105–120 °C for the two samples. The end of hydrocarbon generation at approximately TR = 95% is expected to occur at temperatures around 170 °C and above. MSSV pyrolysis gas chromatography affirms the existence of high wax paraffinic kerogen type–III–II with some marine input for one end member sample (S24). The 4-component compositional kinetic model indicates that the maximum generation of different petroleum components of sample S24 is predicted at lower values of temperature and vitrinite reflectance if compared with sample S27. The other end member of sample (S27) is more typically humic coal-like with type-III kerogen generating mostly gas and condensate.
