Palynological Investigation of TTtex-1 Well, coastal marsh depobelt of Eastern Niger Delta Basin, Nigeria (Published)
Palynofacies analyses of the strata penetrated by TTtex-1 Well were carried out with the aim of investigating the stratigraphic sequence penetrated by the Well to establish palynostratigraphic zones, the relative age and the paleoenvironment of deposition. Sixty-two ditch cutting samples within the interval of 2179 – 3523 m were analyzed. The use of acid in the sample preparation for palynofacies analyses were used. The result of the analyses produced relatively low to abundant occurrences of pollen and spores shows abundance of small, medium, and large sizes of palynomacerals I and II, few occurrences of palynomacerals III and IV. The lithology consists of intercalations of shale and sandstone units with few intercalations of argillaceous sandstone units, this designates the studied interval to be Agbada Formation. The interval studied were dated to be middle Miocene to late Miocene based on the recovered age indicative marker species such as Multiareolites formosus, Zonocostatites ramonae, Crassoretitriletes vanraadshoveni Verrutricolporites rotundiporus, and Racemonocolpites hians. A taxon range zone: Ainipollinite verus zone and Two interval range palynostratigraphic zones: Multiareolites formosus – Zonocostatites ramonae, Verrutricolporites rotundiporus – Crassoretitriletes vanraadshoveni were proposed. The stratigraphic interval studied was deposited in the Coastal-marsh (marginal marine) environments based on paleoenvironmental interpretation of the palynofacies associations and the lithology.
Keywords: Palynofacies, TTtex-1 Well, paleoenvironment, palynostratigraphic zone
Facies Analysis and Paleoenvironmental Reconstruction of Well X, Onshore Niger Delta, Nigeria (Published)
Biofacies and lithofacies analysis of one hundred and ninety-two (192) ditch cutting rock samples from well x, onshore Niger Delta was carried out for the purpose of the paleoenvironmental reconstruction of the rock succession. The objectives were to identify the lithofacies units and species of foraminifera and to use both quantitave and qualitative foraminiferal assemblage to recognise the benthonic foraminiferal biofacies and integrate both results for delineation of paleobathymetric and paleoenvironmental settings of sediments penetrated by well x interval studied. The rock samples were prepared through wet-sieve analysis with 63µm mesh sieve size, and subsequently through dry-sieve analysis with 250µm and 500µm mesh sieve sizes. The prepared rock samples were analyzed to generate data for sedimentological grain-size analysis and foraminifera biofacies assemblages. The grain-size analysis provided lithofacies associations, sand/shale ratio and sorting/gradational profile for the studied intervals of well-x while the micropaleontological analysis identified a total of ninety-three (93) well preserved foraminiferal species from which three (3) biofacies associations were delineated. The biofacies include: Ammonia beccarii, Ammonia beccarii/Bolivina scalprata miocenica, and Haplophragmoides compressa/ Valvulina flexilis biofacies indicating Shallow Inner Neritic, Inner- Middle Neritic, and Outer Neritic – Upper Bathyal paleoenvironment respectively. The result of the sand/shale ratio and lithofacies associations indicated penetration into the Agbada Formation of the Niger delta and deposition within shallow to deep marine paleoenvironmental settings, predominantly as channels, intercalated with overbank and distal bar/bay deposits. Synthesis of the biofacies and lithofacies indicated stratigraphic development between coastal deltaic and upper bathyal paleowater depths.
Keywords: Niger-Delta, Onshore., biofacies, foraminifera, lithofacies, paleoenvironment
Foraminiferal Biostratigraphy of Well Ad, Western Niger Delta (Published)
Micropaleontological analysis of sixty (62) ditch cuttings rock samples collected from interval, 7800 feet to 12,002 feet of well AD, located offshore western Niger Delta was carried out for the investigation of their age and paleodepositional environment. Standard methods and techniques of foraminiferal sample processing and analysis were followed to disaggregate the microfauna from the rock matrix. The studied interval is predominantly made up of 80 to 100 % sandstone, minor shale and siltstone with variable textural properties. Foraminifera study revealed well preserved and diverse species dominated by the calcareous benthic forms. A total of seventy-four (74) foraminiferal species were recovered among which fifty (52) two are calcareous benthic, six (6) are agglutinating forms while sixteen (16) are planktonic foraminifera. On the basis of the faunal assemblage, abundance and diversity of the important foraminiferal events, four (4) foraminiferal zones (Valvulineria spp, Brizalina mandoroveensis, Hanzawaia concentrica and Lenticulina inornata) were recognised and correlated with F300 and F500 to assign an early to middle Miocene age for the sediments. Paleoenvironmental deductions were based primarily on the richness and diversity of foraminiferal species categories. The presence or absence of planktonic foraminifera aided in deciphering open ocean environments. The dominant biofacies associations recorded within the studied section of Well-AD is the Ammonia beccarii biofacies defined by the rare to common occurrences of Ammonia beccarii, Bolivina scalpratamiocenica, Florilus atlanticus and Epistominella vitrea. Brizalina mandoroveensis species, Lenticulina inornata, Hanzawaia strattoni, Eponides eshira, Cribroelphidium galvestonensis and Hanzawaia concentrica were also in association. The Ammonia beccarii biofacies is indicative of the Shallow/Inner Neritic Paleoenvironment, while the Inner Neritic/Middle Neritic Setting is characterized by top occurrence of Valvulineria spp, a rich continuous occurrence of Epistominella vitrea. The paleoenvironment of the studied section of Well-AD is dominantly inner to middle neritic with concomitant minor incursion of outer neritic setting.
Keywords: Age, Niger-Delta, foraminifera, micropaleontology, neritic, paleoenvironment