Modelagem do mCSEM no domínio do tempo usando transformada discreta de Fourier

Abstract

The mCSEM modelling is usually done in the frequency domain, from its theoretical formulation to the analysis of the results. However, the time domain approach is, in principle, capable of providing equivalent information about the geo-electric structure of the subsurface. In this work, we model frequency domain mCSEM data in 1-D environments, then we perform the discrete Fourier transform to obtain time domain results. We simulated marine geological environments with and without the resistive layer that represents the hydrocarbon reservoir. We verified that the time domain data are significantly different when calculated for models with and without hydrocarbons in almost all model configurations. We calculated the results considering variations in the sea depth, in the position of the receivers and in the resistivity of the hydrocarbon layer. We observed the influence of the airwave, even at sea depths greater than 1000m, and although a simple separation of this influence on data is not possible, the time domain allowed us to do an analysis of its effects on the survey. As part of the preparation for the 2-D and 3-D modelling, we also have studied the gain in performance from the use of parallel processing in our task.