Petroleum Potentials of the Nigerian Benue Trough and Anambra Basin: A Regional Synthesis

A review on the geology and petroleum potentials of the Nigerian Benue Trough and Anambra Basin is done to identify potential petroleum systems in the basins. The tectonic, stratigraphic and organic geochemical evaluations of these basins suggest the similarity with the contiguous basins of Chad and Niger Republics and Sudan, where commercial oil discovery have been made. At least two potential petroleum systems may be presented in the basins: the Lower Cretaceous petroleum system likely capable of both oil and gas generation and the Upper Cretaceous petroleum system that could be mainly gas-generating. These systems are closely correlative in temporal disposition, structures, source and reservoir rocks and perhaps generation mechanism to what obtains in the Muglad Basin of Sudan and Termit Basin of Niger and Chad Republics. They are very effective in planning future exploration campaigns in the basins.

Physicochemical,mineralogy,and thermo-kinetic characterisation of newly discovered Nigerian coals under pyrolysis and combustion conditions

In this study,the physicochemical,microstructural,mineralogical,thermal,and kinetic properties of three newly discovered coals from Akunza(AKZ),Ome(OME),and Shiga(SHG)in Nigeria were examined for potential energy recovery.Physicochemical analysis revealed high combustible but low levels of polluting elements.The higher heating values ranged from 18.65 MJ/kg(AKZ)to 26.59 MJ/kg(SHG).Microstructure and mineralogical analyses revealed particles with a rough texture,surface,and glassy lustre,which could be ascribed to metals,quartz,and kaolinite minerals.The major elements(C,O,Si,and Al),along with minor elements(Ca,Cu,Fe,K,Mg,S,and Ti)detected are associated with clays,salts,or the porphyrin constituents of coal.Thermal analysis showed mass loss(ML)ranges from 30.51%to 87.57%and residual mass(RM)from 12.44%to 69.49%under combustion(oxidative)and pyrolysis(non-oxidative)TGA conditions due to thermal degradation of organic matter and macerals(vitrinite,inertinite and liptinite).Kinetic analysis revealed the coals are highly reactive under the oxidative and non-oxidative conditions based on the Coats-Redfem Model.The activation energy(Ea)ranged from 23.81 to 89.56 kJ/mol,whereas the pre-exponential factor(kQ)was from 6.77×10^(-4)/min to 1.72×10^(3)/min under pyrolysis and combustion conditions.In conclusion,the coals are practical feedstocks for either energy recovery or industrial applications.

Mineralogy,physicochemical and oxidative thermal analyses of Cretaceous coals from the Benue Trough,Nigeria

The erratic supply of electricity in Nigeria has renewed interest in the utilisation of coal for energy selfsufficiency and diversification of the national energy mix.In this study,selected coal samples from three regions of the Benue Trough Basin were examined through pore water chemistry,X-ray diffraction(XRD),and thermosgravimetric analysis(TGA).The low pH observed for the Lower Benue Trough(LBT)coals indicates the release of sulphur and acids during oxidation.Mineralogical analyses reveal quartz,kaolinite,montmorillonite,albite,pyrite,gypsum and sodium chlorate in the coal samples.The genetic kaolinite species identified in Imeagha(IMG)coal are detrital kaolinite and the highly crystalline neomorphic kaolinite.Gypsum and jarosite minerals occurred in minor quantities in Garin Maiganga(GMG),whereas significant amount of pyrite was detected in Enugu(ENG)coal.Oxidative thermal degradation resulted in the residual mass(RM)ranging between 4.35%and 56.96%and mass losses(ML)between 43.04%and 95.65%due to the drying,devolatilization,and coke formation in the samples.The most reactive coal examined was GMG coal,whereas the least reactive was IMG coal.Lamja(LMZ),GMG,and OKB coals are suited for electricity generation,whereas ENG and IMG coals can be utilised for cement production.

Petrology, physicochemical and thermal analyses of selected cretaceous coals from the Benue Trough Basin in Nigeria

Abundant coal resources that were previously neglected due to a crude oil boom need revitalisation and integration into the national electricity mix to address the energy demands of the Nigerian population.Selected coal samples from the Benue Trough sedimentary basin in Nigeria were examined by various techniques,including proximate and ultimate analyses,organic petrography,Fourier transform infrared ray spectroscopy,and thermogravimetric analysis.Based on vitrinite reflectance,the Lafia-Obi(OLB),Garin Maiganga(GMG),Imiegba(IMG),and Okaba(OKB)coals are classified as subbituminous,while the Lamja1(LMJ1),Lamja2(LMJ2)and Chikila(CHK)coals are high volatile B bituminous.The Enugu(ENG)coal is on the boundary between subbituminous and high volatile C bituminous.Organic petrographic results indicate vitrinite and fusinite contents steadily increase from the Lower Benue Trough coals to the Upper Benue Trough coals,while semifusinite and total mineral contents follow a reverse pattern.Thermal decomposition occurred in three stages,i.e.,drying,devolatilization,and coke formation above 700°C;and the coal reactivity follows the following order,ENG>IMG>IGH>CHK>LMJ>OKB>GMG>LFB.The higher temperatures(above 900°C)are required to decompose the coals for efficient energy recovery.The LMJ1,LMJ2,OLB,CHK,GMG,and OKB coals can be exploited for electricity power generation.However,the Imeagha and Enugu coals are best suitable for both cement and power generation.