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This study involved the use of well logs from four wells (JAP-1-4) to evaluate the reservoirs' quality and to determine the clay distribution trends of the reservoirs using the neutron-density crossplot in the ''Akbar Field'' Coastal Swamp depobelt, Niger Delta. The results of the analysis show that a total of fifteen (15) reservoirs (A1-A15) were delineated and they are relatively laterally continuous. There is an increase in reservoir thickness as the delta prograded, giving rise to good sand development down-dip at the shallow and intermediate intervals. From the interpreted gamma ray log motifs, it was observed that reservoirs A1-A5, A8, A10 and A12-A14 are tidal channels; A7 and A11 are fluvial channels; A9 and A15 are shoreface sands, while only A6 is of coastal plain deposit. The reservoir porosities show good-excellent values that range from 0.15 to 0.38 v/v (15-38%) except in JAP-1 well where reservoirs A4, A5 and A9-A11 have poor to fair value of 0.11 v/v (11%). Also, the permeability values are good to excellent (1866.24-75873.41 md), except for the few sands in JAP-1 well that are low (3.42-72.82). Additionally, the neutron-density crossplots show that the reservoirs contain mainly laminated and structural clays with few dispersed clays. Despite the presence of these three clay types, the reservoir qualities of the reservoirs are not relatively affected. Although the horizontal fluid flow may not have been affected, the vertical flow could be impaired due to the presence of numerous laminated clay/ shale baffles compartmentalizing the reservoirs.

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The study focuses on the stratigraphic succession and depositional environment in areas around Konshisha, southern Benue Trough. The area is underlain by the Ezeaku Formation and Konshisha River Group. Integrated outcrop, textural and petrographic analysis aided inference of the depositional framework of sediments in the area. Three lithofacies were identified -micaceous sandstone (Facies A), limestone (Facies B), and grey shale (Facies C). Textural analysis indicated that the sandstones are fine grained with mean size ranging from 2.2 to 2.8 phi, very poorly to poorly sorted and deposited in a fluvially-influenced shallow marine setting. Petrographic analysis of the sandstone showed that the sediments have undergone compaction as a result of tectonic stress, shown by the elongate shape of some quartz grains, dominant line contact, and the tilted nature of the beds. Sandstones are both compositionally and texturally sub-mature, implying a proximal source. Results from the petrographic analysis of the limestones reveal micrite as the dominant matrix, with skeletal fragments, pelloids, recrystallized bivalve shells and some mineral grains (quartz and muscovite) present. The depositional environment is probably lagoonal, evidenced by the fine lamination of the limestone beds and low diversity. This study suggests an initial transgressive phase in the Turonian, with the deposition of the grey shale and limestone facies in a shelf -lagoonal setting, and a subsequent regressive phase that led to the deposition of micaceous, ripple-laminated sandstones in a fluvially-influenced shallow marine environment.