Analysis of Ground Magnetic data by Logarithmic curves in parts of Federal University of Petroleum Resources Effurun, Delta State

Abstract

The aim of this study is to introduce a novel technique used for mapping subsurface structures in a sedimentary environment using the magnetic exploration method. Vertical component of the Earth’s magnetic field and its derivative taken at 1.4m above the measured vertical field were acquired in parts of Federal University of Petroleum Resources Effurun, Delta State, using an AMC-6 high precision magnetometer. The datasets were analysed by logarithmic curves. Six magnetic profiles were established in the area five in the strike direction and one along dip lines. A total of ten stations were sampled along each profile with an interstation spacing of 2m. This was followed by the conversion of the vertical field into geomagnetic attributes after the necessary corrections were applied to the data. The data was plotted in logarithm to base two to show the pattern of distribution of the data since the normal plot does not show the distribution clearly as datasets show feeble changes and the readings were close in amplitude values. When datasets are closed we check for the skewness of the data. The result obtained showed regions of high data concentration which corresponds to a peak (highest point) on the logarithmic plot and indicates anomalous zones of interest within the subsurface. Map of vertical components of the area showed steep slope (closely spaced contours) observed towards the North-Eastern part of the area while at the central part, anticlinal structures which decrease gentle outwardly were observed and a gentle slope which decreases towards the west was also observed. The result indicates the presence of anticlinal structures in the subsurface which have valley-like depressions between them