Department of Earth Sciences

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Biostratigraphy and Paleoenvironmental Studies of Onigbedu Sediments, Ewekoro Local Government, Ogun State.
(IRE Journals, 2019-12-01) UMOH EKAETE ENAMEKERE, OLANIYAN OLAMIDE RILWAN
Abstract- Eleven (11) outcrops samples in vertical succession at the blast surface of the purechem cement mine, Onigbedu, Ewekoro from the Akinbo and Ewekoro Formationsat an interval of one meter depth were reconnoiter in order to establish the lithofacies, age and paleoenvironment. The biostratigraphic results indicated that the study area was deficient of calcareous nannofossils as well as planktonic foraminifera but benthic foraminifera were moderate to abundant in sample S2 of the Akinbo formation and samples L2, L3, L4, L5, L6, and L7 of the Ewekoro formation. Microfacies analysis carried out on three selected samples of the Ewekoro formation harmonized with already existing lithofacies classification of the Ewekoro formation as Sample L2 and Sample L4 -Biomicite, Sample L6- Biosparite. The presence of foraminifera species consisting of rare calcareous benthic, absence of Planktics and Calcareous nannofossils indicate deposition in a shallow water. Foraminiferal assemblage is characterized by Valvulineria sp, Quinqueloculina sp, Hanzawaia concentrica, Calcareous indeterminate and Ostracod suggesting sediments deposition in a marginal marine setting (Coastal Deltaic). The results of the analyses also indicate that these outcrop samples were deposited during the late Paleocene epoch, estimated numerical age of 56.8Ma to 57.3Ma and straddling the Valvulineria martinezensis Niger Delta Benthic Foraminiferal zone.
Calcareous Nannoplankton Analysis of Well BL-2, Deepwater Offshore, Niger Delta Basin
(Journal of Mining and Geology, 2019-01-01) Umoh, Oyafunke, O.A E.E.; Ighodaro, E.J
Sequence Stratigraphy and biostratigraphy are recent tools that are being developed and incorporated together for the understanding of stratigraphic distribution and prediction of source, reservoir and seal rocks. These tools were used to analyze well BL-2, within the depth intervals of 6000ft - 8880ft offshore, Niger Delta. Calcareous Nannoplankton assemblages encountered in the study were used in determining the biozone and age of the samples of the penetrated well. Intercalation of sand and shale lithologies obtained from the well logs suggests the well BL-2 penetrated the Agbada Formation. Three nannozones were determined - NN10, NN11 and NN12, two sequence boundaries and three maximum flooding surfaces with ages and 5.0Ma, 5.8Ma, 7.0Ma respectively were delineated and used to divide the stratigraphic succession into depositional sequences and their corresponding system tracts. Highstand and Transgressive system tracts were identified in each of the three depositional sequences. However the absence of lowstand system tract can be inferred to have resulted from erosion by succeeding transgressive system tracts. The alternation of highstand and transgressive system tracts is inferred to provide the desired combination of reservoir and source rock required for hydrocarbon generation. The unit's age is Late Miocene to Early Pliocene.
CHEMOSTRATIGRAPHIC ANALYSIS OF ASN-1 WELL, UGHELLI DEPOBELT, NIGER DELTA
(Global Scientific Journals, 2020-03-01) Umoh, Ekaete Enamekere; Ebahor, Abraham Isreal
Chemostratigraphy is a valuable tool in the correlation of sedimentary successions based on sensitive changes in concentration of key major, minor and trace elements. Fifteen ditch cutting samples collected within the depth range of 5660ft - 8550ft from well ASN-1, Greater Ughelli depobelt, Niger Delta were analysed for their litho logic and elemental concentration with the aim to investigate depositional environment, source area composition, provenance and the weathering index of the samples. The lithologic descriptions were interpreted from gamma ray well logs and petrographically and their elemental values were analysed using AAS Spectrophotometer. The Lithosection indicates shale and sand units’ indexes inferring maturity and area of deposition, the depositional environment is a transitional zone (fluvial deltaic terrain). The weathering indexes CIA, CIW and PIA values ranges from 1.06 to 41.8, on average indicates low to moderate weathering in the source area with weathering of some sand fraction. Various calculated values of the weathering indices: Chemical Index of Alteration (CIA), Plagioclase Index of Alteration (PIA), Chemical Index of Weathering (CIW) and scatter plots of formulated ratios of Al/Na vs chemical index of alteration (CIA) were plotted to determine the weathering indexes. This also inferred their recycling processes are insignificant. The clay content is low and feldspars are averagely high implying immaturity.
FORAMINIFERAL ANALYSIS AND PALEOENVIRONMENTS OF SEDIMENTS IN WELL -AA, DEEPWATER OFFSHORE, NIGER DELTA, NIGERIA.
(GLOBAL JOURNAL OF PURE AND APPLIED SCIENCES, 2020-03-27) UMOH, EKAETE ENAMEKERE; FASINA, PEACE OLUWASEYI
Foraminiferal analysis was carried out on twenty five (25) ditch cutting samples from well -AA, offsore Niger Delta covering a depth interval of 9000ft-11025f. The study was aimed at age deduction, zoning the well, and interpreting the paleoenvironment of deposition. Lithostratigraphic description carried out on the sample revealed that the bulk lithofacies constitute shale with streaks of sand (fine-medium) between 9170ft - 9210ft and 9360ft -9380ft. The entire analysed interval was barren of planktonic foraminifera while depth 9960ft revealed a spot occurrence of Lagena spp, representing the only calcareous benthic foraminifera recovered in the entire interval. Few to common occurrences of deepwater agglutinated foraminifera were found in the well, dominated by some species of Haplophragmoides spp and Haplophragmoides narivaensis. Other foraminifera with rare and scattered occurrence includes, Cribrostomides spp, Bathysiphon spp, Troahammina spp, Cyclammina spp, Cyclammina cancellata, Valvulina spp, and Glomospira spp. The only microfaunal associated accessory recovered is ostracod at depth 1080ft. The analysed intervals was assigned a Middle – Late Miocene (N17 and older age) based on the FDO of Haplophragmoides narivaensis. The environment of deposition is based on the distribution of typical deep water arenaeceous foraminifera species recovered in the study. The predominance of the arenaeceous forms over calcareous forms suggest outer shelf environment of deposition.
An Integrated Studies: Bio facies Analysis of Sediments of Well B -1, Offshore, Niger Delta
(IRE Journals, 2020-04-01) UMOH, EKAETE ENAMEKERE
Abstract- Biofacies analysis of twenty five samples from well B-1, offshore Niger Delta, based on the nannofossil and foraminiferal content were carried out. The aim was to identify the biozones, determine the age and reconstruct paleoenvironment of the sediments. From the diagnostic taxa recovered two biozones were recognized for the nannofossil NN7 (Discoater Kugeri zone) and NN6 Cyclicargolithus Floridanus zone), while the foraminferal zone identified include N13-N12 and N11, both Calcareous nannofossil and Foraminiferal analysis indicate middle Miocene. A proximal to distal inner neritic (6440 – 6860ft), middle – outer neritic (6860 - 7640ft), shallow inner neritic (7760 – 9140ft) and middle – outer neritic (9290 – 10340ft) paleoenvironment was recognized for the study intervals. Paleoenvironmental deductions were based primarily on benthic foraminiferal assemblage and abundance and diversity of species. Presence or absence of planktic foraminifera and calcareous nannofossils also helped in deciphering Open Ocean
Nanno-Bioevents and Condensed Section of Well –BXW Offshore, Niger Delta, Nigeria
(International Journal of Scientific Engineering and Science, 2020-01-01) UMOH, Ekaete Enamekere
Ditch cutting samples from well - BXW in the offshore area of the Niger Delta were studied for their lithofacies and nannofossil content with the aim of establishing age and stratigraphic significance of the condensed section delineated from the well. Standard procedures were employed for lithologic description and nannofossils preparation techniques. The lithofacies penetrated thick shale units and some sandy shales. The rich and well preserved calcareous nannofossils recovered allowed the establishment of four zones of NN12, NN11, NN9 and ?NN8 belonging to early Pliocene - Late Miocene (Zanclean - Tortonian stage). The condensed sections identified were tied to 5.0Ma, 5.8Ma, 7.4Ma and 9.5Ma maximum flooding surfaces. Detailed analyses of condensed sections as important framework for assessing: age; acme /characteristic assemblages of nannofossils within the condensed section; paleo-depositonal environment; potential source rock; information on rate of sedimentation, and a glimpse of the oceanographic condition in the studied basin was presented.
Occurrence and Environmental Implications of Calcareous Nannofossils in Surface Sediments of the Western Gulf of Guinea: off Lagos Coast, South-western Nigeria
(Journal of Environment and Earth Science, 2016-01-01) ADAMOLEKUN, Olajide J.; UMOH, Ekaete E.
The application of calcareous nannofossils in oil exploration, and environmental studies is playing an increasingly important role all over the world. Most recent researches on this subject area in Nigeria are confined/restricted to the oil producing Niger Delta leaving most other areas untouched. This however limits nannofossils’ application in biostratigraphic and paleoenvironmental interpretation of non oil producing areas within the country. Before now, nannofossils occurrence and application have not been documented in the surface sediments of Nigeria. Consequently, calcareous nannofossils have been investigated in thirteen (13) surface sediments samples of the littoral area from the continental shelf of western Gulf of Guinea, off Lagos coast. Primarily, this research was aimed at determining the occurrence (and or non occurrence), and relative abundance of nannofossils in surface sediments of the area with which the age of the sediments, paleoenvironment and paleoecological condition(s) could be determined.The samples were collected with the aid of grab sampler, allowed to dry and subjected to detailed lithologic description. Furthermore, the samples were subjected to nannofossils analysis by standard method of preparation. Both qualitative and quantitative analysis was done using the high power Olympus Transmitted Light Microscope (TLM). The occurrence of nannofossils has been established in the study area (littoral area of the western Gulf of Guinea). Most of the sediments are poorly consolidated, fine to coarse grained sand with little amount of clay ant silt fractions that yielded Pliocene to Recent nannofossils (mainly Pleistocene). A total population of 1132 belonging to five different genera (Calcidiscus, Ceratolithus, Gephyrocapsa, Helicosphera and Reticulofenestra) and seven species were found in the studied samples with Gephyrocapsa caribbeanica being the most abundant (followed by Gephyrocapsa oceanica of a little lower abundance). The species indicate a truly shallow marine environment within recent sediment accumulation.
Use of Sedimentological and Geochemical Parameters to Evaluate the Lithologies and Geochemical (Na/Zn and K/Mn) Ratios of OGE-1 Well, Niger Delta Basin
(J. Appl. Sci. Environ. Manage, 2020-06-01) IGHODARO, OKIOTOR, M.E E.J; UMOH, ITIOWE, K EE
This work focuses on subjecting ninety (90) sidewall core well samples to sedimentological and geochemical parameters to determine the lithologies and the geochemical ratios of the OGE-1 Well in the Niger Delta Basin. The sedimentological analysis with sample description yielded lithologies that are sand, shaly sand, sandy shale and shale. The sand lithologies ranged from fine to coarse grained, well sorted to poor sorted at different depths, while the shale lithologies ranged from light to dark coloured shales which is controlled by the organic matter content in the shale. This finally produced a lithologic frame work of the well. The result of the geochemical analysis led to the creation of the geochemical ratio of Na/Zn (0.739 – 5.610) and K/Mn (21.170 – 69.37) for 90 side wall core samples. Na and K had variations in their graphs showing intermittent alternating abundance downhole. Na and K being components of the weathering of feldspars are indicative of abundance of clay minerals. The variation of the Na/Zn and K/Mn profile indicates the alternate deposition of clay and sand size deposits giving the environment of deposition to be paralic.

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