Abstract
This paper presents interpretation examples of synthetic marine frequency domain CSEM responses from multiple reservoirs of known and realistic geologic models. The electric field responses were decomposed into constituent responses to examine individual reservoirs’ contributions to the EM field. Several realistic geological models of the reservoirs were created with all the structural complexities which are synonymous with the real-life scenario in the Niger Delta. The model has three reservoir layers, tagged 1st, 2nd and 3rd reservoir layers, in 2.5 km water depth at 0.25 Hz frequency. The result shows a clear Normalized Amplitude Ratio (NAR) for each resistive layer, with different detectability strengths of the layers. The most near-seafloor resistive layer, dubbed 1st reservoir layer, is marked by high NAR while the deeper resistive layer shows lower detectability. The value of NAR for each decomposed resistive layer reflects their depth of burial while the sum of individual NAR values correlates with the NAR obtained for the model containing all the resistors. It implies that the magnitude of NAR could be used to deduced the relative depth of burial of a resistive hydrocarbon layer as well as to detect the presence of multiple resistors. The decomposition of the resistive layers could be of help during real-time exploration surveys and suggest possible multiple hydrocarbon layers. The study also allows the understanding that the resultant response of two vertical reservoir layers is a summation of the strength of the individual layer, which differs from the seismic response of the same layers.
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Acknowledgements
I am deeply indebted to the Key Lab of Submarine Geosciences and Prospecting Techniques of Ministry of Education, Ocean University of China and my former doctoral supervisor, Prof Li Yuguo for the doctoral fellowships and training from which I gained lots of experience that enable me to further research in finite element modelling.
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Folorunso, A.F. Simple interpretation examples of synthetic frequency domain marine CSEM data from multiple structurally complex hydrocarbon reservoirs. Mar Geophys Res 43, 19 (2022). https://doi.org/10.1007/s11001-022-09480-2
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DOI: https://doi.org/10.1007/s11001-022-09480-2