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Item 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.Item 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 maturityItem 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 FieldItem 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.Item 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.Item 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. "Item 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. "Item "Sedimentological characteristics, provenance and hydrocarbon potential of Post Santonian sediments in Anambra Basin, Southeastern Nigeria "(2012) Nton, M. E.; Bankole, S. A."Field studies of outcrop samples from part of Anambra basin, southeastern Nigeria, were investigated to unravel the lithofacies distribution, provenance, palaeotectonic history as well as aspects of hydrocarbon potential of the basin. The sandstone facies of the Nkporo, Owelli, Mamu and Ajali Formations are cross bedded, medium to coarse grained, poorly sorted to moderately well sorted, negatively skewed and leptokurtic to platykurtic. Textural plots and multivariate parameters indicate fluvial to shallow marine environment. Paleocurrents signify southwest direction for the Nkporo and Ajali Formations while the Owelli Formation points to a northwest direction. The sandstones classify as quartz arenite with heavy mineral assemblages that revealed the presence of zircon, rutile, tourmaline, staurolite, sillimanite, kyanite, garnet and apatite; having ZTR index of 63 %. These typify products of weathering of basement rocks under humid climatic setting with long transportation and/or recycling history. Organic matter quantity of the shales ranges from mass fractions 0.89 % to 3.98 % TOC and Rock-eval parameters indicate immature, poor to fair hydrocarbon potential. Cross plots of rock eval parameters revealed gas proned terrestrially derived Types III and IV kerogen. It can be deduced that the sandstones were sourced from the Adamawa–Abakaliki folded belt and part of Oban Massif while the shales have prospect to generate gas at appropriate maturation, especially from the Nkporo Shale. "Item 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.Item 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. "