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The poor quality of potable water sourced from boreholes and hand dug wells at Yetunde Brown, Gbagada, Lagos informed the integration of geophysical, physicochemical and Water Quality Index (WQI) to assess the condition of groundwater in the study area. Twenty-Five (25) Vertical Electrical Sounding (VES) data were acquired and complemented with water samples collected from three boreholes and two hand-dug wells within the neighborhood of the study area. The VES data were partially curve matched and inverted. Physicochemical parameters were measured in water samples. The results of the VES data revealed four to five geo-electric layers which correspond to the topsoil (with layer thickness and resistivity values from 0.6 to 1.3 m and 20.1 to 361.4 Ωm respectively), clay (with layer thickness and resistivity of 1.7 to 5.2 m and 2.8 to 22.1 Ωm), sandy clay (with layer thickness and resistivity values of 2.8 to 5.9 m and 12.4 to 56.8 Ωm) and clayey sand (with layer thickness and resistivity values of 23.8 to 31.8 m and 7.2 to 94.2 Ωm). The sand in VES 7, 9, 12-18 and 20 has resistivity values ranging from 151 to 331.5 Ωm. The depth to the identified aquifers fluctuates between 23.8 and 90.4 m. The measured iron, chloride and lead ions are above World Health Organization (WHO) recommendation for potable water in some water samples. WQI calculated reflected poor quality for two boreholes only, which could be due to the unconfined aquifers delineated in the second and fourth geo-electric layers making the water vulnerable to contamination. The study recommended that bore hole should be sunk at VES 7, 9, 12, 13, 18 and 20 at depth between 31.8 to 66.6 m for exploitation of good quality water. [ABSTRACT FROM AUTHOR]

The study was carried out to investigate the dissimilar seismic amplitude responses observed in sandstone reservoirs with the same fluid saturation. This challenge now informed the analysis of different amplitude responses from the 'Jay' Field in order to verify the reservoirs fluids around and away from well location based on the integration of Amplitude Variation with Angle (AVA) and seismic inversions. The well log data provided were used to identify hydrocarbon bearing zones and Poisson Ratio analysis. Anomalies from the AVA analysis were investigated using the elastic impedance inversion of the near and far volumes. Crossplots of Lambda-Mu-Rho inversion were produced to relate reservoir incompressibility and rigidity modulus for lithology and fluid determination. Sand E exhibited amplitude increase with angles at well point and also away from well location (red triangle). The approximate elastic impedances of the inverted seismics are almost similar to the log estimates, an indication of good correlation. Integration of incompressibility (Lambda-Rho) and rigidity (Mu-Rho) modulus analyses reveals the presence of gas saturation in reservoir Sand G because low Lambda-Rho coincides with high Mu-Rho from both log estimates and inverted seismics. In the case of Sand D, high Lambda-Rho coincides with high Mu-Rho because it is oil saturated. This study has helped to differentiate the fluids in Sands D and G despite having similar AVA responses. The methods adopted in this work can be useful in hydrocarbon detection from seismic data in fields with similar geological setting. [ABSTRACT FROM AUTHOR]