Palynofacies Analyses of HA-001 well, Offshore Depobelt, Niger Delta Basin, Nigeria Olubusayo A. Olatunji * , Oladotun A. Oluwajana Department of Earth Sciences, Adekunle Ajasin University, Akungba-Akoko P.M.B 001, Nigeria Corresponding Author Email: olubusayo.olatunji@aaua.edu.ng https://doi.org/10.18280/eesrj.090404 ABSTRACT Received: 6 May 2022 Accepted: 7 October 2022 Palynofacies studies of the strata penetrated by HA-001 well were carried out with the aim to establish palynostratigraphic zones and paleodepositional environments. The standard acid palynological method of sample administration was employed to recover the palynofacies, soaking and washing of samples with water for sedimentological analyses and integration of Gamma Ray Log, palynofacies and sedimentological data for interpretation of paleodepositional environments. The study established two new assemblage biozones namely Cyperaceaepollis sp. – Nympheaepollis clarus, and Stereisporites sp. within the sedimentary intervals penetrated in the wells. The Cyperaceaepollis sp. – Nympheaepollis clarus biozones were further subdivided into Nympheaepollis clarus – Echitriletes pliocenicus and Cyperaceaepollis sp. – Elaeis guineensis subzones. The Late Miocene age is associated with the biozones. The lithologic, textural and wireline log data indicated that the intervals studied in the HA- 001 well belong to the Benin Formation and Agbada Formation. Index minerals and accessories are dominated by ferruginous materials, glauconite pellets, carbonaceous detritus, shell fragments and pyrites plus minor mica flakes. Lower delta plain, delta front and prodelta environment of deposition were inferred for the studied well intervals. The research has conformed to international stratigraphic guide for establishment of biozones which serves to increase the knowledge of high resolution biostratigraphy. Keywords: biozones, formation, lithologic, paleodepositional, palynostratigraphic 1. INTRODUCTION The onshore Niger Delta Basin has become mature and its exploration has shifted to offshore. The integration of various geological methods such as palynological, palynofacies, paleoenvironmental analyses are needed for the understanding of the subsurface geology and development of its hydrocarbon potentials. The abundance of forms of pollen and spores can be used to determine biostratigraphic sequences and make paleoenvironmental reconstructions. Industry workers in the Niger Delta Basin have relied on usage of alpha-numeric method for biozonation purposes while some researchers have also used the same method to establish their biozones [1-4]. Hence, standardised biozonation scheme which is in line with the international stratigraphic guideline for the establishment of biozones is necessary. Some researchers made use of only palynomorphs to analyse paleoenvironment of deposition in the Niger Delta Basin [5-11] explained the usage of palynofacies in analysing paleoenvironment of deposition. Research works on palynomorphs and palynofacies for paleoenvironmental analysis are quite limited. Published works on the integration of pollen and spores’ biostratigraphy and biozonation, palynofacies and sedimentology of the Tertiary Niger Delta Basin are scarce to few. The study attempts a classification of biostratigraphic zones using internationally accepted standard guidelines while incorporating palynofacies and sedimentological data with those of wireline in order to achieve a proper stratigraphic sequence in HA-001 well in the Niger Delta Basin. Research works on biostratigraphy of the prolific Niger Delta Basin are still ongoing. Palynostratigraphic zones should be established in conformity with international stratigraphic guide. This will enable generation of standard biozonation schemes in the Niger Delta Basin. This research work has contributed to knowledge by successfully utilising the stratigraphic ranges of the recovered pollen and spores marker species to date the strata penetrated by the well and it has established palynostratigraphic biozones that conform to international stratigraphic guide for establishment of biozone. The work has also been able to integrate palynofacies data, sedimentological and Gamma Ray log data to delineate paleodepositional environment of the stratigraphic successions penetrated by the well. The subsequent part of this paper is as follows: Section two discusses the Geology of Niger Delta Basin, section three describes the materials and methods of the research which are employed in achieving the aim of the work. Section four and five highlights the results and conclusion of the work. 2. GEOLOGY OF NIGER DELTA BASIN HA-001 well lies within latitude 4⁰ 09' 10.9" N and longitude 6⁰ 14' 1.8" E within the shallow offshore depobelt, Niger Delta, Nigeria. The location of the well is shown in Figure 1. The Niger Delta covers a landmass over 105,000 km 2 [12] and falls within longitudes 3° and 9° E and latitudes 4° and 6° N [13]. The recognized sequence in the Niger Delta Basin consists, in ascending order, of the Akata, Agbada, and Benin Formations. Environmental and Earth Sciences Research Journal Vol. 9, No. 4, December, 2022, pp. 151-158 Journal homepage: http://iieta.org/journals/eesrj 151