An integrated study of the Chad Basin Nigeria has been carried out using heat flow, Bouguer gravity anomaly, depth to basement maps and interpreted seismic reflection data of the area. The seismic reflection data show two main structural elements: faults and folds whose primary structural orientation is northeast-southwest. Other features such as grabens and horst which are formed as a result of tensional stress and magnetic intrusive are also identified in the sections. The Bouger gravity anomaly ranges from -10 to -50 mgal with a northeast to southwest trend while the heat flow values ranges from 63.63 to 105.4 m Wm -2 with an average of 80.6 m Wm -2 . The result shows that areas with relatively low heat flux in the southwest and northeast is associated with Bouguer gravity values ranging from -30 to -50 mgal. These parts of the basin also have a higher depth to basement and are associated with low sediment, buried hills and crest of folds. The range of heat flow values computed for this study shows that the basin sediments are thermally mature and therefore has high prospects for oil and gas generation. The graben in the basin is associated with low heat flow and very low negative Bouguer gravity anomaly. The study reveals that a decrease in heat flow is observed with an increasing sedimentary thickness. Thus, by studying the heat flow map, regions of gravity highs and lows can be identified within the Chad basin. Moreover, areas of gravity lows have greater thickness of sediments than areas of gravity highs. Low geothermal gradient causes the formation of oil to begin at fairly deep subsurface levels, but makes the oil window to be quite broad. The heat flow, Bouguer gravity values and seismically determined structural features suggest that the Chad Basin Nigeria has good prospects for hydrocarbon plays in Cretaceous rocks, with high potentials for both structural and stratigraphic traps. The southwestern and northeastern axis of the basin is therefore recommended for further drilling to deeper depth based on the results of this study.

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ABSTRACT:The delineation of possible areas of corrosion along an underground oil pipeline in Ubeji, Delta State, Nigeria was investigated using the horizontal electrical resistivity profiling technique and the Spontaneous Potential geophysical method. The resistivity and self potential values of the soil along the pipeline were obtained using the R-plus resistivity meter. The results show that areas of low resistivity, having values between 98.0 and 116.0 Ohm-m, coincide with areas of high negative spontaneous potential values, in the range -31.0 to -52 mV. The low apparent resistivity and high negative spontaneous potential values are indications that the soil is very corrosive and there is the possibility of the pipeline failure and oil spillage around these hot spots in the future. These methods applied in the study are quick, economic and efficient for detecting likely anodic hot spots along buried pipelines which need to be protected. Routine electrical geophysical investigations along buried oil pipelines should be undertaken for the early detection and prevention of pipeline failure with its attendant environmental, human and economic consequences. @ JASEM Corrosion is the gradual chemical attack and degradation that results in the conversion of metallic materials into oxides, salts or other compounds. Materials such as metals and its alloys (e.g. steel) that have undergone corrosion lose their strength, ductility and other mechanical properties. Corrosion attacks are frequently responsible for most materials failures. Corrosion of underground metallic materials is a very widespread problem.

In this study, we have extracted and analyzed four seismic attributes of Akos oil field to obtain more information about the structures, stratigraphy and hydrocarbon potential of the Akos field from available seismic and a suite of well logs data. Two lithology and reservoirs were delineated from the well logs. Two horizons and growth faults were identified in the seismic sections. For a comprehensive analysis of the structural and stratigraphic understanding of the reservoirs, four seismic attributes variance edge, sweetness, root mean square and relative acoustic impedance were applied to the seismic data. The Variance edge analysis was used to delineate the prominent and subtle faults in the area. The high sweetness regions in the seismic data indicate high amplitude which indicates the presence of hydrocarbon-bearing sand units. The root mean square amplitude analysis also indicates the presence of hydrocarbon in seismic data. The relative acoustic impedance analysis was used for delineating lithology variation in the seismic sections. The result of the seismic attribute analysis has shown that the Akos field has good hydrocarbon prospects.

Geophysical methods can be helpful in mapping areas of contaminated soil and groundwater. Electrical resistivity surveys were carried out at a site of shallow hydrocarbon contamination in Ahoada, South-South Nigeria. This was aimed at evaluating the subsoil conditions and groundwater quality of the area three years after the post-spill clean-up exercise. The geophysical investigation involved the Vertical Electrical Sounding (VES) technique using the Schlumberger configuration and the horizontal profiling method. The data from the two different approaches correlate well, and the generated profiles of the acquired data helped to map the contaminant plume, which was delineated as an area of high interpreted resistivities. The VES result shows that the subsurface layers up to a depth of 49 m is of moderate to high resistivity values (>200 Ώm) that may affect crops and groundwater development in the study area. However good aquifer can still be obtained from the depth of 30 m and above.