Taiwo A Bolaji | Federal University Oye-Ekiti (original) (raw)
Papers by Taiwo A Bolaji
Water Science and Technology, Jun 3, 2022
In this study, water samples from Miocene reservoirs, offshore Niger Delta, and seawater samples ... more In this study, water samples from Miocene reservoirs, offshore Niger Delta, and seawater samples used for water injection were investigated in an attempt to examine the chemistry, evaluate the corrosion behaviour of steel, iron, and aluminium in different aqua media, and evaluate the scaling potentials of the oilfield produced waters (OFPW). Chemical analyses of the waters were determined; corrosion rate measurements were carried out by the weight loss method at room temperature while corrosion kinetics was carried out using conventional methods. Langelier saturation index (LSI), Ryznar stability index (RSI), Larson-Skold index (L-S), Puckorius scaling index (PSI), and aggressiveness index (AI) were evaluated for assessing the corrosiveness and scaling potential of the formation waters, using water quality data. The magnitude of corrosion of these metals was studied for an exposure period of 42 days. Chemical analysis revealed that the waters are slightly alkaline and generally classified as hard, saline water of the Na-Cl type based on its total dissolved solids (TDS). Produced water pH values range from 7.32 to 8.38. Results showed the likelihood of some of the water to form mild to severe scales based on the corrosivity indices, while the seawater samples are classified as 'non-aggressive' and 'aggressive'. Steel has the highest corrosion rate with a value of 3.84 Â 10 À3 mg cm À2 h À1 compared to aluminium with the lowest rate of 0.37 Â 10 À3 mg cm À2 h À1. In most cases, the rate of corrosion of the metals followed the first-order rate constant in some of the samples, and the second-order in others within the first seven days. It was observed that the rate of corrosion follows this order: steel. iron. aluminium. The potential heavy and intolerable corrosion associated with the use of these seawater samples as injection waters is a potential risk that must be handled by adequate treatment.
Heliyon, Feb 1, 2021
The Niger Delta is one of the most prolific hydrocarbon provinces in the world, but information o... more The Niger Delta is one of the most prolific hydrocarbon provinces in the world, but information on basinal hydrogeology is scanty. Oilfield brines from nine producer wells in the Miocene reservoirs (2,472.25–3,532.48 m.b.s.l.), offshore Niger Delta, have been investigated along with two seawater samples to understand their hydrogeochemical characteristics in relation to the host rock mineralogy. Chemical analysis revealed that the waters are slightly alkaline and can be generally classified as saline water of the Na–Cl type based on their total dissolved solids (TDS). On the basis of bicarbonate, chloride, and sulphate ions, they are shown to be of connate origin. Relative abundance of major ions is in the following order: Na > Ca > Mg > K and Cl > HCO3 > SO4. Saturation indices (SI) of selected mineral phases calculated using PHREEQC indicate that the dissolution of iron oxide and carbonate minerals may contribute major ions in the formation water. The preponderance of alkali elements suggests the presence of feldspars, which could have resulted from sediments through which the water flows. An inverse relationship is observed between the resistivity of formation water and its TDS, which could be used to calculate resistivity values of formation waters in the area if the TDS contributions are known. Chemical data suggest that the formation waters were derived from seawater, dominantly altered by reverse ion-exchange processes and subsequently by water-rock interactions. Multivariate statistical analyses (correlation and factor analysis) indicate multiple sources of enrichment of ions in the formation waters.
Environmental Earth Sciences, May 26, 2023
Groundwater is an important water source for agricultural irrigation in Penyang County. Some trad... more Groundwater is an important water source for agricultural irrigation in Penyang County. Some traditional methods such as irrigation coefficient, sodium adsorption ratio, total alkalinity, total salinity and total dissolved solids were employed to assess groundwater quality in this area. In addition, an improved technique for order preference by similarity to ideal solution model was applied for comprehensive assessment. The origin of major ions and groundwater hydrogeochemical evolution was also discussed. Groundwater in Penyang County contains relative concentrations of dominant constituents in the following order: Na ? [ Ca 2? [ Mg 2? [ K ? for cations and HCO 3-[ SO 4 2-[ Cl-[ CO 3 2for anions. Groundwater quality is largely excellent and/or good, suggesting general suitability for agricultural use. Calcite and dolomite are found saturated in groundwater and thus tend to precipitate out, while halite, fluorite and gypsum are unsaturated and will dissolve into groundwater during flow. Groundwater in the study area is weathering-dominated, and mineral weathering (carbonate and silicate minerals) and ion exchange are the most important factors controlling groundwater chemistry.
Environmental Earth Sciences
Energy Exploration & Exploitation
The Turonian-Maastrichtian bituminous sands resource in the Dahomey (Benin) Basin, Southwestern N... more The Turonian-Maastrichtian bituminous sands resource in the Dahomey (Benin) Basin, Southwestern Nigeria, is a potentially economically viable hydrocarbon reserve, which has recently attracted renewed attention. An integrated study involving the use of elemental composition, and geochemical analyses (gas chromatography flame ionisation detector (GC-FID), Fourier transform infrared (FTIR), and gas chromatography mass spectrometry (GC-MS)) were carried out to provide an improved understanding of this resource using geochemical signatures and evaluate the n-alkane distribution of bituminous sands to determine its aliphatic hydrocarbon distribution and the prevailing depositional conditions. Elemental composition shows the dominance of carbon ( Av. 79.8%). The atomic ratios of H/C and O/C, respectively, range from 0.05 to 0.11, and 0.04 to 0.08. SiO2 is the dominant oxide, with concentrations ranging between 73.15 and 80.50 wt. %, while Zn is the dominant trace element. Twenty-three alip...
Recent Research on Geomorphology, Sedimentology, Marine Geosciences and Geochemistry, 2022
Journal of Petroleum Exploration and Production Technology, 2021
The Cretaceous sediments in southwestern Nigeria are host to one of the largest bitumen deposits ... more The Cretaceous sediments in southwestern Nigeria are host to one of the largest bitumen deposits in the world. In the current paper, an integrated study on sedimentology, palynology, and applied petroleum geochemistry of the Maastrichtian-Paleocene Araromi Formation was used to determine the depositional environments and hydrocarbon potentials of the formation on the eastern Dahomey Basin. Four sedimentary lithofacies were identified from core samples, namely, lower limestone (F1); medium to coarse-grained sandstone (F2); lower loosely consolidated sandstone (F3); and shale and siltstone (F4). Sedimentation in the eastern Dahomey Basin occurred mainly in fluvial and shallow-marine (shelf) environments. The palynological assemblages of the Araromi Formation reflect deposition in coastal through brackish water to shallow shelf environment with periods of localized wind-induced storms. The shale and siltstone samples of the Araromi Formation are characterized by total organic carbon (T...
Journal of Geology & Geophysics, 2015
The data is the analytical results obtained for formation water samples and seawater samples used... more The data is the analytical results obtained for formation water samples and seawater samples used in this study. These samples were collected from Freeman field, Offshore, Niger Delta.
Journal of Petroleum Exploration and Production Technology
The Cretaceous sediments in southwestern Nigeria are host to one of the largest bitumen deposits ... more The Cretaceous sediments in southwestern Nigeria are host to one of the largest bitumen deposits in the world. In the current paper, an integrated study on sedimentology, palynology, and applied petroleum geochemistry of the Maastrichtian-Paleocene Araromi Formation was used to determine the depositional environments and hydrocarbon potentials of the formation on the eastern Dahomey Basin. Four sedimentary lithofacies were identified from core samples, namely, lower limestone (F1); medium to coarse-grained sandstone (F2); lower loosely consolidated sandstone (F3); and shale and siltstone (F4). Sedimentation in the eastern Dahomey Basin occurred mainly in fluvial and shallow-marine (shelf) environments. The palynological assemblages of the Araromi Formation reflect deposition in coastal through brackish water to shallow shelf environment with periods of localized wind-induced storms. The shale and siltstone samples of the Araromi Formation are characterized by total organic carbon (T...
Biogenic sulfide production in oilfield systems occurs due to the metabolic activities of sulfate... more Biogenic sulfide production in oilfield systems occurs due to the metabolic activities of sulfate-reducing prokaryotes. These activities of prokaryotes (bacteria and archaea) in production facilities in oilfields leads to unexpected increase in hydrogen sulfide (H2S) concentrations over time in produced fluids from petroleum reservoirs. This widespread phenomenon has proven to have dire consequences, affecting production facilities integrity, personnel safety, environment, the quality and market value of fluids produced from oil reservoirs. Several approaches have been employed over the years to control souring, but the effectiveness of each method differs. This paper reviews the occurrence, consequences, and management of biogenic souring in oilfield reservoirs undergoing waterflooding.
Scientific Reports
Paleogene deposits are extensively exposed in the Eastern Dahomey (Benin) sedimentary Basin in so... more Paleogene deposits are extensively exposed in the Eastern Dahomey (Benin) sedimentary Basin in southwestern Nigeria. Outcrop logging and sampling of lithological sections were systematically carried out at the Ibese Quarry, in order to re-establish the age of sediments and reconstruct their depositional environment using samples rich in organic-walled microfossils. Two formations were recognized; the Ewekoro and Akinbo Formations. Two main lithological units were identified; limestones and carbonaceous shales. Minor lithologies include ferrugineous sandstones and glauconite. Results from the palynological examination show that terrestrial palynomorphs (spores and pollen) dominate over the marine dinoflagellates cyst species in the samples recovered from the Ewekoro Formation, while samples from the Akinbo Formation recorded high abundance with less diversity of the marine dinoflagellates cysts over the terrestrial sporomorph. Age determination/correlation was achieved based on selec...
Scientific Reports
paleogene deposits are extensively exposed in the eastern Dahomey (Benin) sedimentary Basin in so... more paleogene deposits are extensively exposed in the eastern Dahomey (Benin) sedimentary Basin in southwestern nigeria. outcrop logging and sampling of lithological sections were systematically carried out at the ibese Quarry, in order to re-establish the age of sediments and reconstruct their depositional environment using samples rich in organic-walled microfossils. two formations were recognized; the Ewekoro and Akinbo Formations. Two main lithological units were identified; limestones and carbonaceous shales. Minor lithologies include ferrugineous sandstones and glauconite. Results from the palynological examination show that terrestrial palynomorphs (spores and pollen) dominate over the marine dinoflagellates cyst species in the samples recovered from the Ewekoro Formation, while samples from the Akinbo formation recorded high abundance with less diversity of the marine dinoflagellates cysts over the terrestrial sporomorph. Age determination/correlation was achieved based on selected stratigraphic index taxa recovered. the samples from ewekoro formation were dated as late early paleocene to early Middle paleocene, based on the presence of the following pollen keytaxa: Proxapertites operculatus, Retidiporites magdalenensis, Spinizonocolpites baculatus, Mauritidiites crassiexinus, Scabratriporites simpliformis, and Echitriporites trianguliformis. the samples from the Akinbo formation were assigned late Middle paleocene to late paleocene, based on the presence of the following pollen key-taxa: Proxapertites operculatus/cursus, Grimsdalea polygonalis, Retibrevitricolpites triangulatus, Psilatricolporites operculatus, Retistephanocolpites williamsi, Bombacidites sp., Apectodinium homomorphum, and Apectodinium quinquelatum. The environmentally significant palynomorph species indicated differences in paleodepositional environments, ranging from shallow marine in the ewekoro formation at the base, up the stratigraphic sequence, to marginal marine (estuarine) depositional environment in the overlying Akinbo formation. The Dahomey Basin is one of the numerous marginal basins formed along the coast of Africa and Brazil following the opening of the South Atlantic. It is an extensive coastal basin located on the margin of the Gulf of Guinea (Fig. 1). The basin is regarded as one of the active basins among the Nigerian sedimentary basins since its subaerial parts are eroding while deposition is taking place in its distal submarine parts. The Dahomey Basin is a combination of the inland/coastal/offshore basin 1 , that stretches from southeastern Ghana through Togo and Republic of Benin to the southwestern part of Nigeria. It was described by 1 as miogeosyncline, a basin in which volcanism has not been associated with sedimentation. The Eastern Dahomey Basin (the Nigerian sector) comprises of the border flanked by the Benin Republic and Nigeria, and the Benin Hinge line 1 , and consists of approximately 3 km thick Cretaceous to Recent sediments 2. The basin was further classified into three viz: pre-lower Cretaceous folded, Cretaceous and Tertiary chronological stratigraphic units 2 .
Journal of Petroleum Exploration and Production Technology
The Cretaceous sediments in southwestern Nigeria are host to one of the largest bitumen deposits ... more The Cretaceous sediments in southwestern Nigeria are host to one of the largest bitumen deposits in the world. In the current paper, an integrated study on sedimentology, palynology, and applied petroleum geochemistry of the Maastrichtian-Paleocene Araromi Formation was used to determine the depositional environments and hydrocarbon potentials of the formation on the eastern Dahomey Basin. Four sedimentary lithofacies were identified from core samples, namely, lower limestone (F1); medium to coarse-grained sandstone (F2); lower loosely consolidated sandstone (F3); and shale and siltstone (F4). Sedimentation in the eastern Dahomey Basin occurred mainly in fluvial and shallow-marine (shelf) environments. The palynological assemblages of the Araromi Formation reflect deposition in coastal through brackish water to shallow shelf environment with periods of localized wind-induced storms. The shale and siltstone samples of the Araromi Formation are characterized by total organic carbon (T...
Scientific Reports
paleogene deposits are extensively exposed in the eastern Dahomey (Benin) sedimentary Basin in so... more paleogene deposits are extensively exposed in the eastern Dahomey (Benin) sedimentary Basin in southwestern nigeria. outcrop logging and sampling of lithological sections were systematically carried out at the ibese Quarry, in order to re-establish the age of sediments and reconstruct their depositional environment using samples rich in organic-walled microfossils. two formations were recognized; the Ewekoro and Akinbo Formations. Two main lithological units were identified; limestones and carbonaceous shales. Minor lithologies include ferrugineous sandstones and glauconite. Results from the palynological examination show that terrestrial palynomorphs (spores and pollen) dominate over the marine dinoflagellates cyst species in the samples recovered from the Ewekoro Formation, while samples from the Akinbo formation recorded high abundance with less diversity of the marine dinoflagellates cysts over the terrestrial sporomorph. Age determination/correlation was achieved based on selected stratigraphic index taxa recovered. the samples from ewekoro formation were dated as late early paleocene to early Middle paleocene, based on the presence of the following pollen keytaxa: Proxapertites operculatus, Retidiporites magdalenensis, Spinizonocolpites baculatus, Mauritidiites crassiexinus, Scabratriporites simpliformis, and Echitriporites trianguliformis. the samples from the Akinbo formation were assigned late Middle paleocene to late paleocene, based on the presence of the following pollen key-taxa: Proxapertites operculatus/cursus, Grimsdalea polygonalis, Retibrevitricolpites triangulatus, Psilatricolporites operculatus, Retistephanocolpites williamsi, Bombacidites sp., Apectodinium homomorphum, and Apectodinium quinquelatum. The environmentally significant palynomorph species indicated differences in paleodepositional environments, ranging from shallow marine in the ewekoro formation at the base, up the stratigraphic sequence, to marginal marine (estuarine) depositional environment in the overlying Akinbo formation. The Dahomey Basin is one of the numerous marginal basins formed along the coast of Africa and Brazil following the opening of the South Atlantic. It is an extensive coastal basin located on the margin of the Gulf of Guinea (Fig. 1). The basin is regarded as one of the active basins among the Nigerian sedimentary basins since its subaerial parts are eroding while deposition is taking place in its distal submarine parts. The Dahomey Basin is a combination of the inland/coastal/offshore basin 1 , that stretches from southeastern Ghana through Togo and Republic of Benin to the southwestern part of Nigeria. It was described by 1 as miogeosyncline, a basin in which volcanism has not been associated with sedimentation. The Eastern Dahomey Basin (the Nigerian sector) comprises of the border flanked by the Benin Republic and Nigeria, and the Benin Hinge line 1 , and consists of approximately 3 km thick Cretaceous to Recent sediments 2. The basin was further classified into three viz: pre-lower Cretaceous folded, Cretaceous and Tertiary chronological stratigraphic units 2 .
Water Science and Technology, Jun 3, 2022
In this study, water samples from Miocene reservoirs, offshore Niger Delta, and seawater samples ... more In this study, water samples from Miocene reservoirs, offshore Niger Delta, and seawater samples used for water injection were investigated in an attempt to examine the chemistry, evaluate the corrosion behaviour of steel, iron, and aluminium in different aqua media, and evaluate the scaling potentials of the oilfield produced waters (OFPW). Chemical analyses of the waters were determined; corrosion rate measurements were carried out by the weight loss method at room temperature while corrosion kinetics was carried out using conventional methods. Langelier saturation index (LSI), Ryznar stability index (RSI), Larson-Skold index (L-S), Puckorius scaling index (PSI), and aggressiveness index (AI) were evaluated for assessing the corrosiveness and scaling potential of the formation waters, using water quality data. The magnitude of corrosion of these metals was studied for an exposure period of 42 days. Chemical analysis revealed that the waters are slightly alkaline and generally classified as hard, saline water of the Na-Cl type based on its total dissolved solids (TDS). Produced water pH values range from 7.32 to 8.38. Results showed the likelihood of some of the water to form mild to severe scales based on the corrosivity indices, while the seawater samples are classified as 'non-aggressive' and 'aggressive'. Steel has the highest corrosion rate with a value of 3.84 Â 10 À3 mg cm À2 h À1 compared to aluminium with the lowest rate of 0.37 Â 10 À3 mg cm À2 h À1. In most cases, the rate of corrosion of the metals followed the first-order rate constant in some of the samples, and the second-order in others within the first seven days. It was observed that the rate of corrosion follows this order: steel. iron. aluminium. The potential heavy and intolerable corrosion associated with the use of these seawater samples as injection waters is a potential risk that must be handled by adequate treatment.
Heliyon, Feb 1, 2021
The Niger Delta is one of the most prolific hydrocarbon provinces in the world, but information o... more The Niger Delta is one of the most prolific hydrocarbon provinces in the world, but information on basinal hydrogeology is scanty. Oilfield brines from nine producer wells in the Miocene reservoirs (2,472.25–3,532.48 m.b.s.l.), offshore Niger Delta, have been investigated along with two seawater samples to understand their hydrogeochemical characteristics in relation to the host rock mineralogy. Chemical analysis revealed that the waters are slightly alkaline and can be generally classified as saline water of the Na–Cl type based on their total dissolved solids (TDS). On the basis of bicarbonate, chloride, and sulphate ions, they are shown to be of connate origin. Relative abundance of major ions is in the following order: Na > Ca > Mg > K and Cl > HCO3 > SO4. Saturation indices (SI) of selected mineral phases calculated using PHREEQC indicate that the dissolution of iron oxide and carbonate minerals may contribute major ions in the formation water. The preponderance of alkali elements suggests the presence of feldspars, which could have resulted from sediments through which the water flows. An inverse relationship is observed between the resistivity of formation water and its TDS, which could be used to calculate resistivity values of formation waters in the area if the TDS contributions are known. Chemical data suggest that the formation waters were derived from seawater, dominantly altered by reverse ion-exchange processes and subsequently by water-rock interactions. Multivariate statistical analyses (correlation and factor analysis) indicate multiple sources of enrichment of ions in the formation waters.
Environmental Earth Sciences, May 26, 2023
Groundwater is an important water source for agricultural irrigation in Penyang County. Some trad... more Groundwater is an important water source for agricultural irrigation in Penyang County. Some traditional methods such as irrigation coefficient, sodium adsorption ratio, total alkalinity, total salinity and total dissolved solids were employed to assess groundwater quality in this area. In addition, an improved technique for order preference by similarity to ideal solution model was applied for comprehensive assessment. The origin of major ions and groundwater hydrogeochemical evolution was also discussed. Groundwater in Penyang County contains relative concentrations of dominant constituents in the following order: Na ? [ Ca 2? [ Mg 2? [ K ? for cations and HCO 3-[ SO 4 2-[ Cl-[ CO 3 2for anions. Groundwater quality is largely excellent and/or good, suggesting general suitability for agricultural use. Calcite and dolomite are found saturated in groundwater and thus tend to precipitate out, while halite, fluorite and gypsum are unsaturated and will dissolve into groundwater during flow. Groundwater in the study area is weathering-dominated, and mineral weathering (carbonate and silicate minerals) and ion exchange are the most important factors controlling groundwater chemistry.
Environmental Earth Sciences
Energy Exploration & Exploitation
The Turonian-Maastrichtian bituminous sands resource in the Dahomey (Benin) Basin, Southwestern N... more The Turonian-Maastrichtian bituminous sands resource in the Dahomey (Benin) Basin, Southwestern Nigeria, is a potentially economically viable hydrocarbon reserve, which has recently attracted renewed attention. An integrated study involving the use of elemental composition, and geochemical analyses (gas chromatography flame ionisation detector (GC-FID), Fourier transform infrared (FTIR), and gas chromatography mass spectrometry (GC-MS)) were carried out to provide an improved understanding of this resource using geochemical signatures and evaluate the n-alkane distribution of bituminous sands to determine its aliphatic hydrocarbon distribution and the prevailing depositional conditions. Elemental composition shows the dominance of carbon ( Av. 79.8%). The atomic ratios of H/C and O/C, respectively, range from 0.05 to 0.11, and 0.04 to 0.08. SiO2 is the dominant oxide, with concentrations ranging between 73.15 and 80.50 wt. %, while Zn is the dominant trace element. Twenty-three alip...
Recent Research on Geomorphology, Sedimentology, Marine Geosciences and Geochemistry, 2022
Journal of Petroleum Exploration and Production Technology, 2021
The Cretaceous sediments in southwestern Nigeria are host to one of the largest bitumen deposits ... more The Cretaceous sediments in southwestern Nigeria are host to one of the largest bitumen deposits in the world. In the current paper, an integrated study on sedimentology, palynology, and applied petroleum geochemistry of the Maastrichtian-Paleocene Araromi Formation was used to determine the depositional environments and hydrocarbon potentials of the formation on the eastern Dahomey Basin. Four sedimentary lithofacies were identified from core samples, namely, lower limestone (F1); medium to coarse-grained sandstone (F2); lower loosely consolidated sandstone (F3); and shale and siltstone (F4). Sedimentation in the eastern Dahomey Basin occurred mainly in fluvial and shallow-marine (shelf) environments. The palynological assemblages of the Araromi Formation reflect deposition in coastal through brackish water to shallow shelf environment with periods of localized wind-induced storms. The shale and siltstone samples of the Araromi Formation are characterized by total organic carbon (T...
Journal of Geology & Geophysics, 2015
The data is the analytical results obtained for formation water samples and seawater samples used... more The data is the analytical results obtained for formation water samples and seawater samples used in this study. These samples were collected from Freeman field, Offshore, Niger Delta.
Journal of Petroleum Exploration and Production Technology
The Cretaceous sediments in southwestern Nigeria are host to one of the largest bitumen deposits ... more The Cretaceous sediments in southwestern Nigeria are host to one of the largest bitumen deposits in the world. In the current paper, an integrated study on sedimentology, palynology, and applied petroleum geochemistry of the Maastrichtian-Paleocene Araromi Formation was used to determine the depositional environments and hydrocarbon potentials of the formation on the eastern Dahomey Basin. Four sedimentary lithofacies were identified from core samples, namely, lower limestone (F1); medium to coarse-grained sandstone (F2); lower loosely consolidated sandstone (F3); and shale and siltstone (F4). Sedimentation in the eastern Dahomey Basin occurred mainly in fluvial and shallow-marine (shelf) environments. The palynological assemblages of the Araromi Formation reflect deposition in coastal through brackish water to shallow shelf environment with periods of localized wind-induced storms. The shale and siltstone samples of the Araromi Formation are characterized by total organic carbon (T...
Biogenic sulfide production in oilfield systems occurs due to the metabolic activities of sulfate... more Biogenic sulfide production in oilfield systems occurs due to the metabolic activities of sulfate-reducing prokaryotes. These activities of prokaryotes (bacteria and archaea) in production facilities in oilfields leads to unexpected increase in hydrogen sulfide (H2S) concentrations over time in produced fluids from petroleum reservoirs. This widespread phenomenon has proven to have dire consequences, affecting production facilities integrity, personnel safety, environment, the quality and market value of fluids produced from oil reservoirs. Several approaches have been employed over the years to control souring, but the effectiveness of each method differs. This paper reviews the occurrence, consequences, and management of biogenic souring in oilfield reservoirs undergoing waterflooding.
Scientific Reports
Paleogene deposits are extensively exposed in the Eastern Dahomey (Benin) sedimentary Basin in so... more Paleogene deposits are extensively exposed in the Eastern Dahomey (Benin) sedimentary Basin in southwestern Nigeria. Outcrop logging and sampling of lithological sections were systematically carried out at the Ibese Quarry, in order to re-establish the age of sediments and reconstruct their depositional environment using samples rich in organic-walled microfossils. Two formations were recognized; the Ewekoro and Akinbo Formations. Two main lithological units were identified; limestones and carbonaceous shales. Minor lithologies include ferrugineous sandstones and glauconite. Results from the palynological examination show that terrestrial palynomorphs (spores and pollen) dominate over the marine dinoflagellates cyst species in the samples recovered from the Ewekoro Formation, while samples from the Akinbo Formation recorded high abundance with less diversity of the marine dinoflagellates cysts over the terrestrial sporomorph. Age determination/correlation was achieved based on selec...
Scientific Reports
paleogene deposits are extensively exposed in the eastern Dahomey (Benin) sedimentary Basin in so... more paleogene deposits are extensively exposed in the eastern Dahomey (Benin) sedimentary Basin in southwestern nigeria. outcrop logging and sampling of lithological sections were systematically carried out at the ibese Quarry, in order to re-establish the age of sediments and reconstruct their depositional environment using samples rich in organic-walled microfossils. two formations were recognized; the Ewekoro and Akinbo Formations. Two main lithological units were identified; limestones and carbonaceous shales. Minor lithologies include ferrugineous sandstones and glauconite. Results from the palynological examination show that terrestrial palynomorphs (spores and pollen) dominate over the marine dinoflagellates cyst species in the samples recovered from the Ewekoro Formation, while samples from the Akinbo formation recorded high abundance with less diversity of the marine dinoflagellates cysts over the terrestrial sporomorph. Age determination/correlation was achieved based on selected stratigraphic index taxa recovered. the samples from ewekoro formation were dated as late early paleocene to early Middle paleocene, based on the presence of the following pollen keytaxa: Proxapertites operculatus, Retidiporites magdalenensis, Spinizonocolpites baculatus, Mauritidiites crassiexinus, Scabratriporites simpliformis, and Echitriporites trianguliformis. the samples from the Akinbo formation were assigned late Middle paleocene to late paleocene, based on the presence of the following pollen key-taxa: Proxapertites operculatus/cursus, Grimsdalea polygonalis, Retibrevitricolpites triangulatus, Psilatricolporites operculatus, Retistephanocolpites williamsi, Bombacidites sp., Apectodinium homomorphum, and Apectodinium quinquelatum. The environmentally significant palynomorph species indicated differences in paleodepositional environments, ranging from shallow marine in the ewekoro formation at the base, up the stratigraphic sequence, to marginal marine (estuarine) depositional environment in the overlying Akinbo formation. The Dahomey Basin is one of the numerous marginal basins formed along the coast of Africa and Brazil following the opening of the South Atlantic. It is an extensive coastal basin located on the margin of the Gulf of Guinea (Fig. 1). The basin is regarded as one of the active basins among the Nigerian sedimentary basins since its subaerial parts are eroding while deposition is taking place in its distal submarine parts. The Dahomey Basin is a combination of the inland/coastal/offshore basin 1 , that stretches from southeastern Ghana through Togo and Republic of Benin to the southwestern part of Nigeria. It was described by 1 as miogeosyncline, a basin in which volcanism has not been associated with sedimentation. The Eastern Dahomey Basin (the Nigerian sector) comprises of the border flanked by the Benin Republic and Nigeria, and the Benin Hinge line 1 , and consists of approximately 3 km thick Cretaceous to Recent sediments 2. The basin was further classified into three viz: pre-lower Cretaceous folded, Cretaceous and Tertiary chronological stratigraphic units 2 .
Journal of Petroleum Exploration and Production Technology
The Cretaceous sediments in southwestern Nigeria are host to one of the largest bitumen deposits ... more The Cretaceous sediments in southwestern Nigeria are host to one of the largest bitumen deposits in the world. In the current paper, an integrated study on sedimentology, palynology, and applied petroleum geochemistry of the Maastrichtian-Paleocene Araromi Formation was used to determine the depositional environments and hydrocarbon potentials of the formation on the eastern Dahomey Basin. Four sedimentary lithofacies were identified from core samples, namely, lower limestone (F1); medium to coarse-grained sandstone (F2); lower loosely consolidated sandstone (F3); and shale and siltstone (F4). Sedimentation in the eastern Dahomey Basin occurred mainly in fluvial and shallow-marine (shelf) environments. The palynological assemblages of the Araromi Formation reflect deposition in coastal through brackish water to shallow shelf environment with periods of localized wind-induced storms. The shale and siltstone samples of the Araromi Formation are characterized by total organic carbon (T...
Scientific Reports
paleogene deposits are extensively exposed in the eastern Dahomey (Benin) sedimentary Basin in so... more paleogene deposits are extensively exposed in the eastern Dahomey (Benin) sedimentary Basin in southwestern nigeria. outcrop logging and sampling of lithological sections were systematically carried out at the ibese Quarry, in order to re-establish the age of sediments and reconstruct their depositional environment using samples rich in organic-walled microfossils. two formations were recognized; the Ewekoro and Akinbo Formations. Two main lithological units were identified; limestones and carbonaceous shales. Minor lithologies include ferrugineous sandstones and glauconite. Results from the palynological examination show that terrestrial palynomorphs (spores and pollen) dominate over the marine dinoflagellates cyst species in the samples recovered from the Ewekoro Formation, while samples from the Akinbo formation recorded high abundance with less diversity of the marine dinoflagellates cysts over the terrestrial sporomorph. Age determination/correlation was achieved based on selected stratigraphic index taxa recovered. the samples from ewekoro formation were dated as late early paleocene to early Middle paleocene, based on the presence of the following pollen keytaxa: Proxapertites operculatus, Retidiporites magdalenensis, Spinizonocolpites baculatus, Mauritidiites crassiexinus, Scabratriporites simpliformis, and Echitriporites trianguliformis. the samples from the Akinbo formation were assigned late Middle paleocene to late paleocene, based on the presence of the following pollen key-taxa: Proxapertites operculatus/cursus, Grimsdalea polygonalis, Retibrevitricolpites triangulatus, Psilatricolporites operculatus, Retistephanocolpites williamsi, Bombacidites sp., Apectodinium homomorphum, and Apectodinium quinquelatum. The environmentally significant palynomorph species indicated differences in paleodepositional environments, ranging from shallow marine in the ewekoro formation at the base, up the stratigraphic sequence, to marginal marine (estuarine) depositional environment in the overlying Akinbo formation. The Dahomey Basin is one of the numerous marginal basins formed along the coast of Africa and Brazil following the opening of the South Atlantic. It is an extensive coastal basin located on the margin of the Gulf of Guinea (Fig. 1). The basin is regarded as one of the active basins among the Nigerian sedimentary basins since its subaerial parts are eroding while deposition is taking place in its distal submarine parts. The Dahomey Basin is a combination of the inland/coastal/offshore basin 1 , that stretches from southeastern Ghana through Togo and Republic of Benin to the southwestern part of Nigeria. It was described by 1 as miogeosyncline, a basin in which volcanism has not been associated with sedimentation. The Eastern Dahomey Basin (the Nigerian sector) comprises of the border flanked by the Benin Republic and Nigeria, and the Benin Hinge line 1 , and consists of approximately 3 km thick Cretaceous to Recent sediments 2. The basin was further classified into three viz: pre-lower Cretaceous folded, Cretaceous and Tertiary chronological stratigraphic units 2 .