Sedimentological and palynostratigraphical modeling of sediments penetrated by KW field wells, onshore western Niger Delta Basin, Nigeria.

Sedimentological and palynostratigraphical studies were performed on 189 ditch-cutting samples composited at 50 ft intervals from four well sections located in KW field, onshore western Niger Delta Basin, Nigeria, using sieving and visual microscopic observations, hydrochloric and hydrofluoric acids digestion methods to determine their lithological character and palynologic content of the sedimentary successions. The basis of these data is to interpret the lithofacies and biostratigraphy, establish the age of the strata, establish the palynological zones and infer the environments of deposition. Five lithofacies delineated based on the sedimentological study were very coarse sand, coarse to fine sand, shaly sand, muddy sand, and sandy to silty shale. The age of the sedimentary successions ranges from Early Miocene to Pliocene based on the bio-assemblages of these key species. The Early Miocene age is characterized by the occurrence of , , , , , , , , , and The Middle Miocene age is characterized by the FAD of , the occurrence of , in association with , , , , , , and The Late Miocene age is characterized by the occurrence of , sp., sp., , sp. (, sp., sp., , and The Pliocene age is characterized by the basal occurrence of in association with , sp., sp., sp., and The boundary between the Early Miocene and Middle Miocene from the studied oil well sections is marked by the first appearance datum (FAD) and numerical maximum occurrence of and and FAD of The boundary between the Middle and late Miocene is defined by the LAD of the quantitative top and numerical maximum occurrence of , and the numerical maximum occurrence of . The boundary between the late Miocene and the Early Pliocene is marked by the first appearance datum (FAD) and the numerical maximum occurrence of the numerical maximum occurrence of , and the highest abundance of Four palynozones PAZ-1, PAZ-2, PAZ-3, and PAZ-4, and ten sub-zones were erected. Finally, Fluvial-coastal to shallow marine environments of deposition were inferred for the sedimentary successions using sedimentological study, nature of organic matter, and association of key environmentally-sensitive biomarker species.