ABSTRACT
Ninety (90) ditch cutting samples collected from Research and Development Division, Nigerian National Petroleum Cooperation (NNPC) composited between 1000ft-6830ft (5830ft) in JOOAK-1 well located in the Anambra Basin were processed for sedimentological analysis. Eleven (11) of these samples from 2650ft to 5930ft (3280ft) were processed for foraminifera analysis. A biostratigraphical distribution chart and lithostragraphical framework embracing lithofacies, biozonation, age and paleoenvironment were established for the well. The sedimentary successions penetrated consist of fourteen (14) lithofacies units, these are from oldest to youngest: Sandy Shale unit one (1) 6600ft to 6830ft, Shale unit two (2) 6430ft to 6530ft, Sandy Shale unit three (3) 6030ft to 6380ft, Shaly Sand unit four (4) 5860ft to 6010ft, Shale unit five (5) 5650ft to 5750ft, Shaly Sand six (6) 5350ft to 5630ft, Shale unit seven (7) 2620ft to 5330ft, Sandy Shale unit eight (8) 2480ft to 2550ft, Shale unit nine (9) 2260ft to 2340ft, Sandy Shale unit ten (10) 2200ft to 2240ft, Shaly Sand unit eleven (11) 2080ft to 2180ft, Sandy Shale unit twelve (12) at 2040ft, Sandstone unit thirteen (13) 1740ft to 1920ft, Sandy Shale unit fourteen (14) 1000ft to 1660ft respectively. Four (4) minerals were identified in the analysed section of the well and they include; Mica, Iron Oxide (Haematite), Feldspar and Quartz. The petroleum play elements also include four (4) seals/cap rocks, four (4) seats and four (4) reservoirs. A total of eighty (80) foraminifera species were recovered; four (4) planktic, nine (9) calcareous benthic and sixty seven (67) agglutinating benthic. Seven (7) informal biozones were errected for the well and include: Textularia laminata zone, Haplophragmoides species zone, Cribrononium texana zone, Ammobaculites coprolithiformis zone, Rheophax species zone, Bolivina afra zone, Valvulineria species zone. The occurrence of few planktic foraminifera species; Acarinina mackannai, Globigerina eugibina, Globigerina species., Hedbergella delrioensis suggest Inner Neritic environment. A Maastrichtian - Paleocene age was assigned for the analysed (2650ft -5930ft) interval of the well: Paleocene age (2650ft – 4330ft) was assigned to the strata which were marked by the occurrence of Haplophragmoides excavata, Cribronium texana, Acarinina mckannai, Ammobaculites coprolithiformis while a Maastrichtian age (4650ft – 5930ft) was assigned to the strata marked by the co-occurrence of Hedbergella delrioensis and Bolivina afra.
