Lithostratigraphy and Sequence Stratigraphy of Ultra-Deep E-Field, Eastern Niger Delta: Reservoir, Geological and Biostratigraphical Evidence

The ultra-deep offshore, eastern Niger Delta is marked by rapid, cyclic deposition of thick units of siliciclastic sediments ranging from deep marine to non-marine environments, deposited into rapidly subsiding sub-basins occurring along the slope of the continental margin. This rapid deposition resulted in thick third-order sequences and systems tracts. Patterns of deposition were analysed from seismic reflection configuration and well-log patterns. Lithofacies patterns critical for systems tract recognition were interpreted from well logs and tied to seismic sections where possible. Sediment accumulation plots were constructed and employed to interpret the location of stratigraphic condensation, key surfaces, diffuse boundaries between systems tracts and evaluate the significance of condensed sections. The origin of these condensed sections is caused by major allocyclic changes associated with transgression and shifting of the deltaic depocenter that fed the area. The regional change in condensation through time was interpreted as reflecting avulsion of the shallow marine sediment source. The compilation of sediment accumulation plots also showed a major increase in sedimentation approximately 2.4 Ma; caused by the influx of the prograding shallow marine sediments. Wells located in distal regions in this field are more condensed [steeper slope] than proximal locations. The resulting analyses of this study showed that the basin-floor fan has the highest rate of deposition and could be identified as a gentle slope in the line of sediment accumulation. In the distal regions of the field, TST’s are characterized by sediment starvation because most of the sediments are trapped in the proximal areas. The maximum flooding surfaces [MFS’s] were recorded in deep water as condensed sections.  Secondary condensed sections were delineated and interpreted to have deposited above the top basin-floor fan surface [tbfs] and top slope fan surface [tsfs]. In addition to traditional first downhole occurrence biostratigraphy, the database also contains information on nannofossil abundance. The sands encountered in the reservoirs are correlatable indicating a relatively longer period of depositional cycle.Keywords:  Lithostratigraphy, Sequence stratigraphy, Eustacy, Reservoir geology, Biostratigraphy, Ultra-deep Offshore, Eastern Niger Delta.DOI: 10.7176/JEES/10-7-06Publication date:July 31st 202

Seismic Stratigraphy and Reservoir Characterization of ‘E’ Field Sediments: Inferences from South-Eastern Late Miocene - Pliocene Records, Offshore Niger Delta

Studies of Late Miocene – Pliocene continental shelf and slopes sediments on the south-eastern continental margin, Niger Delta (a broad region from the shelf – slope break extending to the ultra-deep waters: > 1500m), have revealed markedly different responses to sea level fluctuations. Significant features of the stratigraphy include  siliciclastic-dominated facies consisting principally of one or more of the following genetic types: deltaic distributary mouth bars, channel and shoreface sands, barrier beach, shelf and offshore turbidites. These sands are Late Miocene – Early Pliocene in age and were deposited in deep water settings on the slope of the ‘Y’ field by a range of depositional processes that include slumps, debris flows and turbidity currents. Most of these sands could be interpreted to relate to periods of base level fall, if not Global Eustatic lowstands. Working within a sequence stratigraphic framework, eight (8) sequences have been delineated on the basis of reflection termination patterns. The major sequences were related to sea level fall during which the shelf was exposed to erosion. A cross section of the stratigraphic correlation drawn showed that the horizons are laterally continuous. However, pinch-out channel sands and lenticular sandbodies are evident. The recognition of depositional surfaces on the stratigraphic cross-sections allows subdivision of the stratigraphy into systems tracts: HST, FSST, TST and LST. On the seismic package, three (3) main seismic surfaces with distinct chronostratigraphic expressions are evident. They include non-marine, marine and fault plane surfaces. In addition, clinoform strata in the basin-margin setting of this field have relatively flat topsets and sloping clinoforms. On the shelf settings, a composite surface exists consisting of the merged sequence boundary, otherwise marked and interpreted as 4.2 Ma sequence boundary, transgressive surface (TS) and maximum flooding surface (MFS), unless separated by an incised valley fill (IVF). In the ‘Y’ field, failure, slumping and re-sedimentation processes that cause base-of-slope thickening in response to gravity and geotropic flows modify the slope. Furthermore, within the same basinal setting, affected by the same sea level rise, the facies boundaries are diachronous. Keywords: Seismic stratigraphy, Petrophysics, Sea level change, South-eastern, Miocene – Pliocene Sedimentation, Offshore Niger Delta DOI: 10.7176/JNSR/11-14-04 Publication date:July 31st 202

Evaluation of nephrotoxicity effects of the methanol leaf extract of A. angustifolia in Wistar rats

Background: Agave angustifolia is a common traditional remedy in localities for disease treatment. This study focussed on evaluating the nephrotoxicity activity of the methanol extract of A. angustifolia leaf. Methods: Twenty-five Wistar rats of both sex were randomly shared into five groups. Group 1 received 10 mL/kg distilled water, group 2 gentamicin 80mg/kg, extract groups (3, 4 and 5) were placed on 100 mg/kg, 200 mg/kg and 400 mg/kg of A. angustifolia leaf extract  administered orally through an orogastric tube for 14 days. The rats were sacrificed using chloroform, and their kidneys were harvested, weighed and immediately fixed in 10% buffered formalin for histological analysis and blood samples were collected by cardiac puncture for biochemical and haematological analysis. Results: Results showed there was no marked difference in the levels of the packed cell volume (PCV) in all the concentrations of the extract as well as the controls. The gentamicin group showed a remarkable rise in the serum urea and creatinine level when compared to both the control and extract groups. Similar effects were observed in the 100 mg/kg and 200 mg/kg of the extract. However, severe kidney injury was observed in the group treated with 400 mg/kg of the extract. Conclusions: Despite the beneficial potential of A. angustifolia, it also exhibited toxic effects on the kidney thereby causing significant damage to the kidney morphology at higher doses. The damages inflicted in these tissues are dose-dependent. Therefore A. angustifolia should be taken in low doses within shortest period of time

A rare case of left additional renal artery in a Nigerian goat

The report of the occurrence of additional renal arteries in domestic animals is rare in the literature. We report a case of an additional renal artery in the left kidney found in a Red Sokoto goat cadaver. The additional renal artery originated from the abdominal aorta 3.80 cm cranial to the origin of the main renal artery. The additional renal artery was relatively long, being 6.30 cm from its origin to the cranial pole region of the kidney where it supplied the kidney. This to the best of our knowledge is the first report in the literature indexed in the Medline of an additional renal artery in a goat