Browsing by Author "Nton, M. E."

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Aspects of hydrocarbon potential and clay mineralogy of the patti formation, southern Bida Basin, Nigeria
(Department of Geology, 2013) Nton, M. E.; Okunade, A.
"Among the major lithostratigraphic units making up the southern Bida basin are the Lokoja and Patti Formations, overlain by the Agbaja Ironstone. Outcrop samples from the associated shales and claystones units of the Patti formation were examined and characterized to deduce the hydrocarbon potential of the associated shales as well as determine the clay mineralogy in other to deduce the provenance and the palaoclimatic setting of thr basin. Altogether, a total of sixteen samples, made up of ten (10) shale and six (6) claystones were analyzed for this study. Field relationships show that the sediments are cyclical. The shales are dark to greyish while the claystones are milky to whitish. Within the sequences are associated ironstone, sandstones and mudstone. The result of Total Organic Carbon (TOC) ranges from 1.73 to 3.45 wt%, which is greater than 0.5 wt% threshold for clastic rocks to be considered as good source rocks. The Hydrogen Index(HI) ranges from 28 to 79 mgHC/gTOC. This value reveals terrestrial type IV organic matter. Cross plots of Hydrogen Index (HI) versus Oxygen Index (OI), S2 vs TOC indicate types III and type IV organic matter. In addition, cros plot of HI vs Tmax shows immature sediments and mainly type IV organic matter. Tmax values range from 418 to 428oC while the Production Index (PI) ranges from 0.04 to 0.13, which further indicate immature sediments. The clay mineralogy reveals kaolinite as the major clay mineral type, comprisisng 21.28 to 60.48%, dickite (6.00%) whiles the non-clay minerals are mainly quartz, hemalite and feldspar. It can be deduced that the shales are immature with terrestrial organic matter having potential to generate gas at appropriate maturation. The Prevalence of kaolinite is attributable to weathering of feldspar-rich, rocks from the adjoining basement rocks under warm, humid climatic setting. "
Aspects of source rock evaluation and diagenetic history of the akinbo' shale eastern dahomey basin, southwestern Nigeria
(Department of Geology, 2006) Nton, M. E.; Ezeh, F. P.; Elueze, A.A.
"The Akinbo Formation comprises a sequence of mostly dark, pale-greenish grey, laminated shale, slightly glauconitic shale, sandy shale with subordinate claystone lenses. Selected subsurface samples of the shaly facies as penetrated by Akinside 1582 well in eastern Dahomey basin, were investigated by sedimentological, mineralogical and geochemical parameters to ascertain the hydrocarbon potential and deduce the influence of variations of clay mineral indicators on the prospect. Values of total organic carbon (TOC) range from 0.46 to 1.98wt. % while the soluble organic matter (SOM) ranges from 71 to 1940 ppm and portrays that the organic matter is fair to good and adequate. Bitumen ratios have values of 15.25 to 98.98mg ext/gTOC which suggest that the sediments are immature to marginally mature. Average major elemental composition indicates 68.08% SiO2 17.55% Alc23. 4.07%K2O, 1.82%CaO, 1.57%Na2O, 1.29%MgO,• 0.62%Fe,03 and 0.50%MnO. A moderate increase in K2O from 2.26 to 4.92wt. % with depth was observed and this corresponds with increase in illite content. Equally, an increase in AI203/ (Fe203 + MgO) ratio from 7.27 to 22.07 with depth points to increasing diagenetic conditions. Illite and illite/smectite (mixed layer clays) dominate the clay mineral assemblage (>50%) while kaolinite and smectite (ca.35%) are comparatively low. Kaolinite and smectite were observed to disappear with depth as well as an increase in illite crystallinity. Smectite disappearance occurs at approximately vitrinite reflectance of 0.5 %(VRo) and illite crystallinity values are from 0.16 to 1.6°20 , which are within values of normal burial diagenesis. It can be deduced that the shale is a potential source rock varying from immature to marginally mature with prospects to generate gas rather than oil at appropriate thermal maturity. The clay mineral diagenetic indicators show that the hydrocarbon potential might have been affected by geothermal and tectonic history. "
Aspects of structures and depositional environment of sand bodies within tomboy field, offshore western Niger Delta, Nigeria
(2009) Nton, M. E.; Adesina, A. D.
" Sand bodies deposited across normal growth faults and associated rollover anticlines are critical reservoirs for the accumulation of oil and gas. This paper addresses aspects of structures and depositional environments of some sand bodies within the Tomboy field, offshore western Niger Delta. Structural interpretation was undertaken to identify and assign faults found in the 3-D seismic volume. Time and depth structure maps in combination with well logs were used to produce for five horizons, namely: H1 to H5 and identify the depositional environments respectively. Two major growth faults (F4 and F7 which are normal, listric concave in nature), three antithetic (F1, F3 and F6) and two synthetic faults (F2 and F5) were identified. Structural closures identified as rollover anticlines, and displayed on the time/depth structure maps; suggest probable hydrocarbon accumulation at the downthrown side of the fault F4. Point bars, distributary channel and mouth bars, barrier island and tidal channels are the depositional environments. This study shows that the Tomboy field is made up of sand bodies deposited in different environments across normal, growth faults and associated rollover anticlinal structures. "
Evaluations of turonian limestone formation exposed at nigercem-quarry, Nkalagu, southeastern Nigeria: a geochemical approach.
(" The pacific journal of science and technology ", 2009) Ikhane, P. R.; Folorunso, A. F.; Nton, M. E.; Oluwalaanu, J. A
" A geochemical study of Nkalagu limestone of the Lower Benue Trough as exposed at Nigeria Cement Company (NIGERCEM) was carried out. The study aims at the determination of major oxides and trace elements of the limestone exposed in the quarry using X–Ray Fluorescence Spectrophotometer (XRF) and Atomic Absorption Spectrophotometer (AAS) respectively as well as reconstructing the depositional history of the deposit. Petrographic study was also done to enhance the determination of biogenic contents of the deposit. Results of fifteen (15) samples collected for analysis put the range major elements as follow: CaO (46.56 – 54.15%), SiO2 (3.12 – 10.04%), Fe2O3 (0.23 – 1.37%), MgO and Al2O3 (0.72 – 1.27%) and (0.65 – 1.90%) respectively. Also, the trace elements contents expressed in ppm were found to be 1653 – 3306 for Fe, 76 – 1543 for Mn, 600 – 1035 for Sn and 4.5 – 53 for Zn. Interpretation of these results suggest a shallow marine possibly an off – shelf depositional model for the formation. "
Facies evaluations and paleoenvironmental reconstruction of the turonian nkalagu formation, south eastern Nigeria
(2012) Oyebolu, O. O.; Oluwalaanu, J. A.; Nton, M. E.; Folorunso, A. F.; Ikhane, P. R.
The Turonian Nkalagu Formation exposed at NIGERCEM (Nigerian Cement Company) within the Lower Benue Trough was studied in this work in order to determine and establish the lithostratigraphic successions and reconstruct the paleoenvironment of the deposition. Two major litho-facies were delineated. The first is matrix-supported bioclastic shell lag wackestone facies which account for about 70% of the carbonates. The second is a massive fossil-poor micritic limestone. However, using the fossil contents, five distinct micro-biofacies were recognized namely: massive lithoclastic floatstone, bioclastic wakestone, siliceous fossil-poor limestone, bioclastic (bivalve debris) wackestone and bioclastic packstone. The litho-clast consists of probably shallow water transported materials while still in various degrees of lithification from shelf into deeper basin. Many of the lithoclasts are sub-angular whereas others have rounded shape. Textural gradient was upward fining and algae were completely absent which is typical of shallow calcareous marine sediments of the photic zone. The trends of the textural characteristics fall in pattern correlatable with the different facies outlined in the study. Thus, the evidence from this study has put Nkalagu Formation as a deposition in shallow marine environment but later displaced into relatively deeper water, probably that of the off-shelf zone, by some sedimentary flow mechanisms.
Facies model building of integrated multiscale data in Dn-Field, Onshore, Niger Delta, Nigeria
(2015) Nton, M. E.; Arigbe, O. D.
This study employs 3D Post-Stack Time-Migrated seismic data from the DN-Field, within the Coastal Swamp depobelt of the Niger Delta in predicting lithofacies and fluvial facies of OVK-1 sand bodies in the Agbada Formation, as a tool to identify new drillable prospects. A lithofacies model for OVK-1 reservoir sand body was generated after upscaling using Most Of, as the averaging method. Calibrated by fluvio-facies at the well locations, channel sands were identified in OVK- 1 reservoir interval using Stochastic Sequential Indication Simulation (SSIS) algorithm. Based on lithofacies, fluvial facies and biofacies analyses, a terrigenous and shallow fluvio-deltaic fill within a lowstand system tract was evident. Petrophysical properties including porosity, volume of shale and effective porosity were upscaled, guided by facies model and then Stochastic Gaussian Simulation (SGS) algorithm was used to produce the model. Porosity model predicted sand layers having maximum porosity of 27.5% which implied very good reservoir potential. However, the volume of shale model with values from 0.45 to 0.50 incorporates silt and clay and indicates marginal reservoir potential. The study identifies four potential reservoir intervals with thickness ranging from 9.1 to 38.5 m. The effective porosity in OVK-1 ranges from 0.10 to 0.30 and identified fluvial facies such as floodplain, channel sand, levee and crevasse splay sand. Facies model show a good sand distribution with minor shale localized in the western part of the Field. The central part of the model has good reservoir qualities, evident by low volume of shale values and high porosities. This study helps to identify a potential unexplored drillable prospect on OVK-1 sand body south-west of DN-2 well. Successful drilling of the identified prospect could increase the reserve of the Field
Hydogeochemical assessment of surface water and ground water quality in Agbowo-Orogun area of Ibadan, southwestern Nigeria
(Bachudo Science, 2007) Nton, M. E.; Adejumo, S. A.; Elueze, A. A.
"The Agbowo-Orogun area of Ibadan, which is within the basement complex of southwestern Nigeria, is underlained by banded gneiss of the migmatites-gneiss complex. A total of thirty-five water sample, made up of thirty-two from groundwater and three from surface water, were analyzed for their physico-chemical characteristics with the aim of assessing their quality and usability. Results of some physico-chemical parameters show average values of 8.61 pH; 749 49ps/cm EC; 218 50 mg/l TDS; 84.40 turbidity; 323.14 pt/co unit colour; 54.94 mg/l Na‘; 49.75mg/l Ca2*; 28.24mg/l Mg , 23 54 mg/l K*. 1 05 mg/l Fe* 229 14 mg/l HCO; 128.23 mg/l Cl'; 14 86mg/l NO3; 7.30mg/l SO<2; 4 60 mg/l PO<3 and 1 31 mg/l F Average values of total hardness (TH) and sodium absorption ratio are 230 68 mg/l and 1 95 respectively. The relative abundance of cations is in the order of Na*>Ca2*>Mg2*>K*>Fe2* while those of anions are; HC03'>Cr>N0j'>S0«2'>P042 --F R-mode factor analysis shows five factor loadings and bi-log plots of TDS versus Na*/ (Na* ♦ Ca2*) all indicate that the bulk of the chemistry of the water is modified by weathering of the associated rocks. Six water groups were identified, based on characterization using the pipor bilinear diagram These include; Ca- (Mg)-Na- HCO3, Ca-(Mg)-Na-CI-(SO<)-HC03, Ca-(Mg)-HC03, Ca-Mg-(S04>-HC03, Ca-(Mg)-SC>4 and Na-(K)-HC03 thus reflecting diverse effects of bedrock lithologies, base exchange processes, precipitation and weathering Both water sources are in general, slightly alkaline with low to medium sodium hazards The pH, Ca2* and SO42' are within tns permissible limits of WHO standard for both water sources. Concentrations of Na*, NO3 Cl', HCO3 conductivity and TDS are higher than maximum permissible limits for the surface water and may be attributed to anthropogenic effects However it can be observed that both the groundwater and surface water sources are suitable for agricultural purposes while the groundwater in particular, is acceptable for domestic uses. "
HYDROCARBON GENERATIVE POTENTIAL OF CRETACEOUS SEDIMENTS OF KANADI-1 WELL, BORNU BASIN, NIGERIA
(2016) Nton, M. E.; Ekom, J. C.
The hydrocarbon potential and paleodepositional environment of Cretaceous sediments from the Borno Basin, Nigeria, were assessed by Rock-eval pyrolysis and biomarker geochemistry. The Total Organic Carbon (TOC), soluble organic matter (SOM) and genetic potential (GP) values ranged from 0.52 – 0.82wt%, 455.64 – 1003.04 ppm and 0.23 – 0.63 mg/g, respectively. These values suggested that the sediments were moderately rich in organic matter. The Hydrogen Index (HI) values (19 – 85 mgHC/gTOC) and cross plots of Hydrogen Index (HI) versus Oxygen Index (OI), classified the sediments as types 111 and IV organic matter which had potential oto generate mainly gas. The T and Production Index (PI) values ranged from 339 – 436C and 0.08 – 0.32 max while the Production Index (PI) ranged from 0.08 – 0.32, respectively, suggesting low maturity. Biomarker data revealed the presence of C to C steranes and oleanane which indicated organic matter from mixed sources with 27 29 more terrigenous contribution. The dominance of C over C and C also supported higher terrigenous input. 29 28 27, Various thermal maturity parameters computed from the terpanes and steranes distributions in the sediments indicated low thermal maturity. The C /C – C Homohopane index and Pr/Ph values ranged from 0.06-0.24 35 31 35 and 0.23 – 2.52 respectively. These values suggested organic matter deposited under anoxic to suboxic conditions. The results of this study showed that the sediments had potential to generate mainly gas at appropriate thermal maturity
Hydrochemical assessment of surface water in part of South-eastern Nigeria
(Mineral wealth, 2001) Elueze, A. A.; Ephraim, B. E.; Nton, M. E.
"The area of study occurs mainly within the Calabar Flank and part of the adjacent basement terrain of the Oban Massif. The latter is composed of mainly migmatitic gneisses, phyllites, amphibolites, granites, schists and granodiorites, while the major lithologies of the Calabar Flank include carbonates, shales, claystones and sandstones. This study aims at determining the quality and usability of the water, in addition to ascertaining the possible pollutants and ways to ameliorate their effects. Results of some physical and hydrochemical parameters have average values of 5.53pH, 77.4mg/I TDS, 17.8mg/l Na+, 5.5mg/l Ca2+, 13.2mg/l Cl , 3.3mg/l S042', 0.7mg/I NO'3, and 49.6ms/cm conductivity. The water hardness and sodium absorption ratio (SAR) are respectively 20.5mg/l and fi.fi. The total hardness, Ca2+, S042' are higher for the water draining the carbonate rock environs, while the TDS, Na+, conductivity and Cl"" are greater in the basement rock areas. Hydrochemical parameters in the piper trilinear diagram, as well as the Gibbs plot, respectively suggest that the water is of sodium bicarbonate facies, and dissolved solids are mostly products of weathering. Application of R-mode factor analysis suggests that the main components of the water characteristics are related to hydrological, lithological and environmental controls. The factor containing CO32- and HCO3"", is derived from the carbonate rocks in the area, whereas Na+ and K+ which are possibly transported in solution as base exchange of clay minerals, notably characterize the basement rocks. The group showing enrichment in Cl , Mg2+ and NO3 is considered to be associated with environmental control, through precipitation of meteoric water, while the presence of S042"" is linkable to the aeration of sulfide minerals in the area. On the whole, the water is slightly acidic with low sodium hazard. It therefore satisfies the World Health Organisation (WHO) standards for domestic, agricultural and other industrial uses requiring usual treatment such as filtration and disinfection."
" Lithofacies and Organic Geochemical Studies of Akinside 1582 Well, Eastern Dahomey Basin Southwestern Nigeria "
(Nigerian Association of Petroleum Explorationists, 2011) Nton, M. E.; Otoba, O. W.
"Subsurface samples from the Akinside 1582 well, located within the eastern Dahomey Basin were evaluated to determine the lithofacies, depositional environment, and hydrocarbon potential of the basin. The sediments within the interval 138-197m consist of limestones, shales, mudstone and glauconite; thus representing sediments belonging to the Ewekoro and Akinbo Formations. The limestones are greyish, highly indurated, partly recrystallised and reveal six microfacies notably biosparite, shelly biomicrite, biomicrite, pel-biosparite, sandy-pelmicrite and sandy-biomicrite. The presence of gastropods, pelecypods, echinoderm, coralline algae, foraminifera and other skeletal debris indicate a shallow marine environment of deposition for the limestone. Total organic carbon (TOC) for the sediments range from 0.10 to 0.58wt% and 0.59 to 0.62wt% for the Ewekoro and Akinbo Formations respectively while soluble organic matter (SOM) are correspondingly 392ppm and 887 to 2472ppm. These suggest a poor through moderate to adequate organic matter. Plot of HI versus Ol indicates Type III and IV kerogens. Tmax value range from 362 to 467°C and cross plot of HI versus Tmax points to mainly immature to early mature sediments. The terpanes and sterane distributions indicate a marginally mature status for the sediments. Pristane/phytane ratio ranges from 0.13 to 0.24 and 1.88 for the Akinbo and Ewekoro Formations respectively, thus indicating both anoxic and oxic conditions of deposition. The abundance of pentacyclic triterpane of oleanane and hopane skeletons and C27 to C29 regular steranes in the bitumen, indicate mixed source rocks (marine and terrestrial) for the sediments. However, ternary plot of C27, C29 and C29 steranes strongly amplify terrestrial organic matter with prospect to generate gas rather than oil in the basin at appropriate maturation. "
MINERALOGICAL INVESTIGATION OF CORROSION PRODUCTS IN PROCESSING MACHINES
(THE NIGERIAN SECURITY PRINTING AND MINTING COMPANY (NSPMC) LIMITED, LAGOS RESEARCH AND DEVELOPMENT DEPARTMENT, 1997) Nton, M. E.
Organic geochemical appraisal of limestones and shales in part of eastern Dahomey Basin, southwestern Nigeria
(Journal of mining and geology, 2004) Elueze, A.A; Nton, M. E.
"The major lithostratigraphic units of the eastern Dahomey Basin are the Araromi, Ewekoro and Akinbo Formations. Field studies show that the Araromi and Akinbo Formations contain shaly facies, while the Ewekoro Formation contains essentially fossiliferous limestones. The Araromi shales are dark and bituminous, while those of the Akinbo are fissile and concretionary. Selected subsurface and outcrop samples of these lithotypes were analysed to ascertain their palaeodepositional environments and hydrocarbon prospects. Total organic carbon (TOC) of the limestones and shales range from 0.10 to 1.00 wt.% and 0.20 to 1.60wt% respectively. Bitumen yields are 896.20, 108.70 and 376.80ppm correspondingly for Araromi, Ewekoro and Akinbo Formations. Bitumen ratios are 68.70, 28.30 and 72.70mgext/g TOC respectively, for the three succeeding formations. CPI values and pristane/phytane ratios are 1.29, 1.19, 0.99 and 1.53, 1.33, 1.17, respectively for Araromi, Ewekoro and Akinbo Formations. Cross-plots of isoprenoids/n-alkanes show that the organic matter falls within the terrestrial and transitional environments. However, the fossil assemblages of the limestones made up of coralline algae, pelecypods, echinoids, gastropods and few other skeletal debris, indicate a nearshore marine environment. Organic petrography reveals preponderance of vitrinites (Type III O.M.) with subordinate inertinites (Type IV) in all the three formations. The dominance of terrestrial O.M. indicates gas rather than oil proneness of the kerogen. N-alkane profiles, plots of bitumen ratios with depth and the presence of unresolved complex mixture hydrocarbons in most gas chromatograms, indicate immature status for the kerogens. This suggests insufficient cooking of the sediments."
Organic geochemical characterization and hydrocarbon potential of subsurface sediments from Anambra basin, southeastern Nigeria
(2011) Nton, M. E.; Awarun, A. O.
"Subsurface samples of Mamu Formation from Ezimo 1235 and Enugu 1327 wells, located within the Anambra Basin were examined for organic geochemical characterization and biomarker content in order to determine the lithofacies association, hydrocarbon potential as well as the palaeodepositional environment. The sediments are made up of siltstone, dark coal, highly fissile shale and mudstone. Selected samples, made up of shale and coal from both wells were subjected to Rock Eval and gas chromatography/mass spectrometry (GC-MS) analyses. Results of the Total Organic Carbon (TOC) ranges from 5.15 to 69.56wt%, Soluble Organic Matter (SOM) values ranges from 286 to 1700ppm while the Generative Potential (GP) ranges from 10.02 to 311.86kgHC/t. These values suggest that the source rocks are moderately to fairly rich in organic matter. Hydrogen Index (HI) values range from 95-381 mgHC/gTOC and indicate types II and III kerogen. Cross plots of HI against OI signify types II and III kerogen which also indicate oil and gas prone source rocks. Tmax values of 422-437oC and Bitumen Ratio of 6.34 to 101.1 mg ext/gTOC signify low maturation level for the source rock. Ratios of C29 hopane βα/ αβ, C30 βα/αβ, and 22S/22S+22R C32 hopane range from 0.32 to 1.18; 0.21 to 0.57; and 0.13 to 0.52 respectively, and suggest immature organic matter status. Carbon Preference Index (CPI) value ranges from 1.33 to 1.97 suggests immature source rock of terrestrial origin. High values obtained from the C24 tetracyclic/C24 tricyclic terpanes and the C19/ C20 tricyclic terpane ratios, (1.52-2.64) and (0.54- 1.54) respectively, also portray terrigenous organic matter contribution. The presence of C27 to C29 steranes and diasteranes, signify mixed sources (marine and terrigenous) with prospects to generate both oil and gas; however, the dominance of C29 over C28 and C27 amplify higher contribution of terrigenous materials. The terrigenous input is further amplified by the Pr/Ph ratio ranging from 5.44 to 7.81. Cross plots of Pr/nC17 against Ph/nC18 also denote terrigenous sourced organic matter deposited in oxidizing environment. The high ratio of C30/C29Ts, indicates source rocks deposited under suboxic conditions. It can be deduced that the sediments are immature, and were deposited in a suboxic, low Eh environment. They are potential source rocks which are moderately to fairly rich in organic input with substantial amount of terrestrial organic matter, having prospects to generate gas at appropriate maturation. "
Petrography, compositional characteristics and stable isotope geochemistry of the ewekoro formation from ibese corehole, eastern Dahomey basin, southwestern Nigeria
(Bachudo science, 2016) Nton, M. E.; Adeyemi, M. O.
"Subsurface samples of the predominantly carbonate Ewekoro Formation, obtained from Ibese core hole within the Dahomey basin were used in this study. Investigations entail petrographic, elemental composition as well as stable isotopes (carbon and oxygen) geochemistry in order to deduce the different microfacies and depositional environment. Petrographic study reveals the presence of dolomite, biomicrite, sandy biomicrite, and biosparite facies. Preserved pore types such as; intercrystaline, moldic and vuggy pores were observed as predominant conduits for fluids. The major element oxides ranges are; CaO (39.79 - 53.98wt.%), SiO2 (1.29-25.37 wt. %) Al2O3 (0.43-3.77 wt. %), K2O(0.04-0.27wt. %), Fe2O3 (0.74-2.35 wt. %), and Na2O (<0.01-0.05 wt. %). Cross correlation of the major oxide contents shows that Al2O3, K2O, Na2O, TiO2, Fe2O3 and P2O5 are associated with aluminosilicates and their low concentrations indicates that the basin was free of suspended clays and other aluminosilicates materials during carbonate sedimentation. The relatively high concentration of SiO2 and its interrelationship with other major oxides, suggests SiO2 has strictly influenced the sedimentation of the carbonate hence would have been contributed as free silica, probably from beaches and not as aluminosilicates. The Mn/Sr ratio reveals an influence of diagenesis on the mineralogy of the carbonates. The Mg/Ca ratio ranges from 0.02 and 0.1 (av. 0.04), with an outlier value of 0.1, indicating a strong diagenetic influence and the precipitation of dolomite in the mixing zone The isotopic composition of ᵹ13C (-1.9%o to 0.79%o) shows a discrepancy from modern carbonate sediments. The average estimated formational temperature of the limestone is 32.5°C. The ᵹ13O versus ᵹ18O bivariate diagram indicates that the limestone is predominantly average marine limestone with chalk and late cement. The values of depositional setting (Z), estimated from ᵹ13O and ᵹ18O composition support a diagenetic influence on the Ewekoro Formation. The U/Th ratios (-0.25 to 2.3; av. 1.2) and Ce anomaly (0.70 - 0.94, av. 0.85) indicate a predominantly oxygenated environment with little fluctuation in bottom water oxygen level. "
" Petrophysical evaluation and depositional environments of reservoir sands of x field, offshore Niger delta, Nigeria "
(2009) Nton, M. E.; Adebambo, B. A
" This study involves the use of geophysical well logs to characterize four reservoir sand bodies contained in four wells offshore Western Niger Delta. The well logs include caliper, SP, gamma ray, resistivity, neutron (NPHI), density (RHOB) and sonic logs. The logs were obtained in digital data format and a Paradigm's petrophysical software, Geolog was used to process the data into log images. This aided the visual identification of lithologies and potential reservoirs. The reservoirs are contained in the Agbada Formation of the Niger Delta and are composed of sandstone and unconsolidated sands. The sands are predominantly medium to coarse grained with shale intercalations in some horizons. Thickness ranges between 33-60ft (10 to 18 metres). The reservoir characteristics are controlled by depositional environment and depth of burial. From gamma ray log motifs, the reservoirs are inferred to be deep sea turbidite fans and tidal ridge sands. Porosity and permeability values are high with average values of 25% and 4500 millidarcies respectively. Shale content is generally low across the reservoir sands with average values of 15%. The sands are characterized by high relative permeability to oil, Km Km is as high as 1.0 in some horizons. This suggests that oil can be produced relative to water. Generally, porosity and permeability are known to decrease with depth of burial in the Niger Delta. However, a situation of increased porosity and permeability with depth of burial was observed in one of the reservoirs. This can attributed to the preservation of secondary porosity in a mechanically stable, compaction resistant framework of quartz grains. . " "
Pore pressure detection and risk assessment of OBL oil field, offshore Niger delta, Nigeria
(2014) Nton, M. E.; Ayeni, M. D.
The Niger Delta is a prolific petroleum sedimentary basin in the Gulf of Guinea and is posed with a major challenge of overpressure development in many of its fields. Integrated study, utilizing 3D seismic data and well logs from four wells, namely; OBL_1, OBL_2, OBL_4 and OBL_5 was carried out in the offshore Niger Delta. The study aims at evaluation of structural influences on pressure development, detection of overpressure zones and consequently examining the risk involved in drilling. Log signatures show decrease in density log values and corresponding increase in sonic log readings in wells OBL_1, OBL_2 and OBL_4. Well OBL_5, reveals increase density log values but decrease sonic log readings. Two regional and few minor faults observed to penetrate the overpressure zones were mapped out and integrated with the surfaces of the tops of the over pressured zones to generate three stratigraphic zones. Aside from under compaction mechanism, the regional faults penetrating the surfaces generated across the overpressure intervals could have influenced pressure development in the wells.
REPORT ON THE PRELIMINARY INVESTIGATION OF ALLEGED EARTH TREMORS IN ODO ONA ELEWE, IBADAN
(2002) Nton, M. E.
Report submitted to the Honourable Minister Federal Ministry of Solid Minerals Development Abuja
(2005) Nton, M. E.
Reservoir characteristics and palaeo-depositional environment of duski field, onshore, Niger- Delta, Nigeria
(Bachudo science, 2016) Nton, M. E.; Rotimi, S.
The Niger Delta is a prolific hydrocarbon producing belt in the southern Nigeria sedimentary basin on the continental margin of the Gulf of Guinea. This study used well log suites to delineate the hydrocarbon reservoirs, depositional environments and lithostratigraphy of the Duski Field, Onshore Niger Delta, Nigeria. A comprehensive interpretation of the three wells revealed five (5) reservoir units with low volume of shale and thickness variations between 24m and 60.20m. The average porosity values ranged from 12% to 34%, with high hydrocarbon saturation in all the reservoir sands. Generally, porosity and permeability values decrease with depth in all the wells. Cross-plots of water saturation (Sw) and porosity (ø) (Buckles plot) revealed that some reservoirs were at irreducible water saturation; hence producing water-free hydrocarbons. Therefore the hydrocarbon accumulation of this field is commercially viable and promising. This study revealed that the reservoir sand units were deposited within marginal marine depositional environment which include fluvial channel, transgressive marine, progradational and deltaic settings.
SEDIMENTOLOGICAL AND GEOCHEMICAL CHARACTERISTICS OF OUTCROP SEDIMENTS OF SOUTHERN BIDA BASIN, CENTRAL NIGERIA: IMPLICATIONS FOR PROVENANCE, PALEOENVIRONMENT AND TECTONIC HISTORY
(2016) Nton, M. E.; Adamolekun, O. J.
Integrated sedimentological and geochemical studies have been carried out on the sediments of the Lokoja and Patti Formations within the southern Bida Basin with a view to deducing the provenance, palaeodepositional characteristics and tectonic history of the sediments. Field observations show that the Lokoja Formation is made up of conglomerates, coarse to medium grained sandstone and claystone while the Patti Formation consists of medium – fine grained sandstone, claystone, shale, siltstone and ironstone. Pebble morphometry of the Lokoja Formation indicates fluvial environment while granulometric study of the sandstone indicates that they are medium to coarse grained and poorly sorted. Sandstone petrography showed that quartz is generally > 65.98 % while feldspar ranged from 6.45 to 25.97 % and classified the basal Lokoja Sandstone as arkose while the upper sequence and the sandy facies of the Patti Formation are subarkose. Heavy mineral assemblages are mainly; zircon, rutile, tourmaline and staurolite, with ZTR index ranging from 62 to 78%, indicating immature sandstone. The dominant major oxide constituent within the Lokoja Formation are; SiO (55.4 - 64.10%), AlO 2 2 3 (18.65 - 19.66%), FeO (1.76-3.15%) while the composition each of MgO, CaO, NaO and KO is < 4%. On 2 3 2 2 the other hand, sediments of the Patti Formation have higher SiO (56.62-79.26%) and relatively lower values for 2 AlO (13.28 - 19.28%) and FeO (0.84 - 1.65%). The trace elements are dominated by Sr (165.4-411.9ppm) and 2 3 2 3 Ba (635-908ppm) in the Lokoja Formation while Zr (644.9-1969.8 ppm) has higher values in the Patti Formation. In both units, Ce (46.6-235.8 ppm), La (25.8-116.4 ppm), and Nd (18.1-95.9 ppm) are the most abundant rare earth elements with both trace and rare earth elements concentrating more in the finer clastics of the Patti Formation. The ternary plots of framework composition indicated a passive continental block provenance, oxidizing and humid paleoclimatic condition for the sediments. The plots of Th-Sc-Zr/10, Th/Co versus La/Sc and KO/NaO against SiO lie within felsic rocks region. The study concluded that the sediments 2 2 2, were sourced from the adjacent south-western and north-central basement complex of Nigeria and deposited in a fluvial setting.