Palynostratigraphy and Lithostratigraphy of Ha-001 Well, Shallow Offshore, Western Niger Delta, Nigeria

Abstract

The sedimentary intervals from HA-001 well have been analyzed for palynological and sedimentological studies with the aim of generating biozonation, maturation and paleoenvironmental results. Seventy-six ditch cutting samples within the depth intervals of 750 -11610 ft were analyzed. There were few to common recoveries of sporomorphs. Sedimentological inferences were derived from the integration of wire line logs, lithologic characteristic and distribution of index accessory minerals which include ferruginous materials, glauconite, pellets, carbonaceous detritus, shell fragments and pyrites plus minor mica flakes. The lithofacies sequences that characterise the HA-001 well intervals include alternating sand and shale units which suggest rapid shoreline progradation deposited in coastal deltaic to shallow marine settings. The entire interval essentially tested the Benin and the Agbada Formation. The grain increases essentially from fine to medium grained, occasionally coarse to granule-sized at the basal part of the well, to dominantly coarse to pebble-sized, occasionally medium to fine-grained at the upper part. Two (2) palynostratigraphic zones of Cyperaceaepollis sp. - Nympheaepollis clarus, and Stereisporiles sp. were established for the well using the International Stratigraphic Guide. The two (2) zones are assemblage range biozones and Late Miocene age was assigned to the interval based on the stratigraphic age range of diagnostic markers such as Psilatricolporites crassus, Echitriletes pliocenicus, Elaeis guineensis, Corylus sp. and Zonocostites ramonae. Thermal maturity on the basis pollen and spores colours indicated maturity to late degree of maturation.