Integration of 3-D and 4-D Time Lapse Geo-Resistivity Techniques for Oil Spill Characterization in Kegbara-Dere, Gokana, Rivers State

William J. S., Udom G. J., Emujakporue G. O.

Abstract: Intensive monitoring of oil spills is required to investigate the dynamic processes which occur in a spill site over a period of time. The use of time-lapse tomographic algorithm is required to obtain the image of the dynamic processes resulting from the hydrocarbon contamination. 3-D resistivity data acquisition usingorthogonal sets of 2-D on a 50 by 100m grid for measuring the resistivity values at various time-lapse phases and monitor the contaminant dynamics in the study area. ERT models from repeated resistivity investigation on the same spot which were conducted at second phase (time-lapse) within nine months, shows a marked reduction in resistivity values. Data interpretation and modelling using earth imager revealed change in the resistivity values, contaminant volume and depth. Subsurface resistivity values at initial phase monitoring is higher than the values obtained from final phase monitoring implying dynamics in contamination and attenuation over time.

Keywords: 3D and 4D geophysics, electrical resistivity, contaminant plume, oil spill, hydrocarbon, depth-slice, time ?lapse, tomography, resistivity anomaly, environmental studies for oil spill, spill remediation monitoring