Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
Geochemical Characteristics of the Campano-Maastrictian Sediments of the Anambra Basin, Southeastern Nigeria - Implication For Provenance, Paleodepositional Environment, Maturity and Tectonic Setting
Okiotor, Michael Edirin (Nigeria Maritime University Okerenkoko) | Ogueh, EDeh Desiree (Western Delta University Oghara)
Abstract The present study investigates the Anambra Basin shales to determine the provenance and maturity of the sediments using standard geochemical techniques. Twelve (12) representative samples recovered from shale sequences of The Mamu Formation and Nkporo Group of The Anambra Basin were studied to determine the sediment provenance, paleoenvironment, diagenetic conditions, maturity as well as the tectonic setting. To consider in detail and establish the inherent constituents of the Major minerals, Trace and Rare Earth elements, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analyses techniques was employed. The detrital minerals determined are Al2O3 (18.27% and 21.16%), TiO2 (1.73% and 1.63%) and Fe2O3 (2.78% \ and 2.85%), for Nkporo Group and Mamu Formation respectively. The enrichment of SiO2, Al2O3 and TiO2 (1.14, 1.94, 3.67 respectively) supported by Chemical Index of Alteration (CIA) of 93.54 & 39.55 and Rb/Sr ratio of 0.57 & 0.40, indicate that the Anambra Basin sediments are matured. TiO2/AL2O3 binary plots, Th/Co Vs La/Sc crossplots, Th-Sc-Zr triplots and Cr, Ni concentration suggest mixed provenance of felsic to mafic source rocks for these sediments. From the log (K2O/Na2O) Vs SiO2 crossplots, a passive margin tectonic setting was determined for these sediments.
- Geology > Structural Geology > Tectonics > Plate Tectonics (1.00)
- Geology > Geological Subdiscipline > Geochemistry (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.77)
- Africa > Niger > Lake Chad Basin (0.99)
- Africa > Nigeria > Lake Chad Basin (0.99)
- Africa > Nigeria > Anambra Basin (0.99)
- Africa > Chad > Lake Chad Basin (0.99)
Prospects and Challenges of Developing Unconventional Petroleum Resources in the Anambra Inland Basin of Nigeria
Onuoha, K. Mosto (1Petroleum Technology Development Fund's Chair in Petroleum Geology, University of Nigeria, Nsukka, Enugu State, Nigeria) | Dim, Chidozie I. (1Petroleum Technology Development Fund's Chair in Petroleum Geology, University of Nigeria, Nsukka, Enugu State, Nigeria)
ABSTRACT The boom in the development of unconventional petroleum resources, particularly shale gas in the United States of America during the last decade has had far reaching implications for energy markets across the world and particularly for Nigeria, a country that traditionally has been Africa’s leading crude oil producer and exporter. The Cretaceous Anambra Basin is currently the only inland basin in Nigeria where the existence of commercial quantities of oil and gas has been proven (outside the Tertiary Niger Delta Basin). The possibility of similarly finding commercially viable resources of unconventional petroleum resources in the basin appears quite attractive on the basis of the existence of seepages of shale oil and presence of coal-bed methane in some of the coal seams of the Mamu Formation (Lower Coal Measures) in the basin. This paper presents the results of our preliminary assessment of the shale oil and gas resources of the Anambra Basin. Our main objective is to locate the zones of very high quality plays within the basin, focusing on their depositional environments (whether marine or non-marine), areal extent of the target shale formations, gross shale intervals, total organic content, and thermal maturity. Data on the total organic content (TOC %, by weight) and thermal maturity of shales from different wells in the basin show that many of the shales have high TOCs (i.e greater than 2%) comparable to known shale gas and shale oil plays globally. Shale oil seepages are known to occur around Lokpanta in south-eastern Nigeria, but there is a general predominance of gas-prone facies in our inland basins indicating good prospects for finding unconventional petroleum in this and other Nigerian inland sedimentary basins. The main challenge to the exploration of unconventional resources in Nigeria today has to do with the absence of the enabling laws and regulatory framework governing their exploration and subsequent exploitation. The revised Petroleum Industry Bill (PIB) currently under consideration in the National Assembly is expected to introduce drastic and lasting changes in the way the petroleum industry business is conducted in the country, but all the provisions of the draft law pertain mainly to conventional oil and gas resources.
- Phanerozoic > Cenozoic > Paleogene (1.00)
- Phanerozoic > Mesozoic > Cretaceous > Upper Cretaceous > Maastrichtian (0.48)
- Phanerozoic > Mesozoic > Cretaceous > Upper Cretaceous > Campanian (0.46)
- Africa > Togo > Dahomey Basin (0.99)
- Africa > Nigeria > Niger Delta > Niger Delta Basin (0.99)
- Africa > Nigeria > Dahomey Basin (0.99)
- (4 more...)
Depth to magnetic basement in the Anambra Basin, Benue Trough of Nigeria from aeromagnetic data: A prelude for hydrocarbon exploration
Olagundoye, Olatunbosun O. (Total Exploration and Production Nigeria Limited) | Okereke, Chiedu S. (University of Calabar) | Edet, Aniekan E. (University of Calabar) | Obi, Dominic (University of Calabar) | Ukpong, Aniediobong (University of Calabar)
Abstract Data transformation, regional-residual separation, trend analysis, and analytic signal (AS) depth estimation were applied to aeromagnetic data covering the Anambra Basin, which is a major depocenter in the Benue Trough, southeast Nigeria, with the primary objectives of accentuating the attributes of magnetic sources and determining if sufficient sediment thickness exists for hydrocarbon generation, maturation, and expulsion. The application of data transformation techniques (such as map projection, merging, and reduction-to-pole) and regional-residual ensured the computation of a crustal magnetic field that would be suitable for magnetic analyses. Results indicate that the magnetic basement in the basin forms an undulating surface overlain by sediments with an average thickness ranging between 4 and 7.5ย km, whereas the maximum thickness reaches 8ย km in some areas. This depth range suggests a promising prospect for source-facies maturation and expulsion. We expect that areas in the study area with these appreciable sediment thicknesses, good preservation of graben fill, and suitable areal closures or fault structures would be favorable for hydrocarbon prospectivity.
- Africa > Niger (1.00)
- Africa > Nigeria > Enugu State (0.28)
- Phanerozoic > Mesozoic > Cretaceous > Upper Cretaceous (1.00)
- Phanerozoic > Cenozoic (0.68)
- Geology > Structural Geology > Tectonics (1.00)
- Geology > Rock Type (1.00)
- Geology > Geological Subdiscipline > Stratigraphy (1.00)
- (2 more...)
- North America > United States > New Mexico > San Juan Basin (0.99)
- North America > United States > Nevada > Dixie Valley Field (0.99)
- North America > United States > Colorado > San Juan Basin (0.99)
- (9 more...)
Hydrocarbon Generation Indication from Source Rock to Reservoir Rock: Case Studies of Anambra and Abakaliki Basins South-Eastern Nigeria
Salufu, Samuel (University of Ibadan, Ibadan, Nigeria) | Onolemhemhen, Rita (University of Ibadan, Ibadan, Nigeria) | Isehunwa, Sunday (University of Ibadan, Ibadan, Nigeria)
ABSTRACT This paper sought to use information from outcrop sections to characterize the source and reservoir rocks in a basin in order to give indication(s) for hydrocarbon generation potential in a basin in minimizing uncertainty and risk that are allied with exploration and field development of oil and gas, using subsurface data from well logs, well sections, seismic and core. The methods of study includes detailed geological, stratigraphical, geochemical, structural,, petro-graphical, and sedimentological studies of rock units from outcrop sections within two basins; Anambra Basin and Abakaliki Basin were used as case studies. Thirty eight samples of shale were collected from these Basins; geochemical analysis (rockeval) was performed on the samples to determine the total organic content (TOC) and to assess the oil generating window. The results were analyzed using Rock wares, Origin, and Surfer software in order to properly characterize the potential source rock(s) and reservoir rock(s) in the basins, and factor(s) that can favour hydrocarbon traps. The results of the geological, stratigraphical, sedimentological, geochemical, and structural, were used to developed a new model for hydrocarbon generation in the Basins. The result of the geochemical analysis of shale samples from the Anambra Basin shows that the TOC values are โฅ 1wt%, Tmax โฅ 431ยฐC, Vitrinite reflectance values are โฅ 0.6%, and S1+S2 values are > 2.5mg/g for Mamu Formation while shale samples from other formations within Anambra Basin fall out of these ranges. The shale unit in the Mamu Formation is the major source rock for oil generation in the Anambra Basin while others have potential for gas generation with very little oil generation. The shale samples from Abakaliki Basin shows that S1+S2 values range from< 1 โ 20mg/g, TOC values range from 0.31-4.55wt%, vitrinite reflectance ranges from 0.41-1.24% and Tmax ranges from423ยฐC โ 466ยฐC. This result also shows that there is no source rock for oil generation in Abakaliki Basin; it is either gas or graphite. This observation indicates that all the source rocks within Abakaliki Basin have exceeded petroleum generating stage due to high geothermal heat resulting from deep depth or the shale units have not attained catagenesis stage as a result of S1+S2 values lesser than 2.5mg/g despite TOC values of โฅ 0.5wt% and vitrinite reflectance values of โฅ 0.6%. The novelty of this study is that the study has been able to show that here there is much more oil than the previous authors claimed, and the distribution of this oil and gas in the basins is controlled by two major factors; the pattern of distribution of the materials of the source rock prior to subsidence and during the subsidence period in the basin, and the pattern and the rate of tectonic activities, and heat flow in the basin. If these factors are known, it would help to reduce the uncertainties associated with exploration for oil and gas in the two basins.
- Phanerozoic > Mesozoic > Cretaceous > Upper Cretaceous (0.68)
- Phanerozoic > Mesozoic > Cretaceous > Lower Cretaceous (0.46)
- Geology > Rock Type > Sedimentary Rock > Organic-Rich Rock > Coal (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Geological Subdiscipline > Geochemistry (1.00)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (1.00)
- Geophysics > Seismic Surveying (0.34)
- Geophysics > Borehole Geophysics (0.34)
- Africa > Nigeria > Anambra Basin (0.99)
- Africa > Nigeria > Gulf of Guinea > Imo > Niger Delta > Niger Delta Basin > Imo Field (0.93)
The comprehensive interpretation of the Mamu Formation in the Anambra Basin involved analyzing sedimentology, biostratigraphy, and palynofacies geology. This analysis revealed that the strata were deposited during the Early Maastrichtian period in a restricted shallow marine environment with influences from fluvial activity. A notable indication of the Early Maastrichtian age was the increasing occurrence and sustainability of planktonic foraminifera, predominantly Textularia hockylensis. The presence of Textularia hockylensis and Textularia sp in KFM 05, Elhasaella sp and Textulana sapittula in KFM 04, and Textulana agglutinans and Textulana Sagitulana in KFM 08 suggests the presence of long-ranging taxa in the studied area of the Anambra Basin, which were deposited at the beginning of a regressive phase. The analysis of palynofacies reflects the depositional environment and cycles associated with progradation and retrogradation. The composition of organic remains in the sedimentary rocks depends on the prevailing environment during deposition and subsequent diagenetic processes. The biostratigraphic analysis of the shales suggests that the high abundance of planktonic foraminifera indicates continuous deposition in a restricted shallow marine environment. The palynofacies elements, including terrestrial-derived plant remains, structured woody materials, opaque organic matter, cuticles, pollen and spores, and minor amorphous organic matter of marine origin, confirm the restricted shallow marine settings of the formation.
- Geology > Sedimentary Geology > Depositional Environment (1.00)
- Geology > Geological Subdiscipline > Stratigraphy > Biostratigraphy (0.88)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.45)
- Africa > Nigeria > Niger Delta > Niger Delta Basin (0.99)
- Africa > Nigeria > Anambra Basin (0.99)
- Africa > Sao Tome and Principe > Gulf of Guinea (0.89)