A New Approach for the Enhanced Interpretation of Marine CSEM Data

Abstract

Abstract

Marine Controlled Source Electromagnetics (MCSEM) method is generally used as a complimentary study to seismic exploration, for increasing the probability of hydrocarbon-reservoir localization in deep water. To improve reservoir detection and characterization, we have developed a new approach for the interpretation of MCSEM data that includes the following four principal steps:

1. Analysis and visualization of the electromagnetic (EM) data, using their transformation into Complex Effective Resistivity (CER). The real and imaginary parts of CER can be considered as new attributes for the MCSEM.
2. Correlation of the real and imaginary parts of Complex Effective Resistivity with seismic data, and the association of CER anomalies with perspective structures discovered previously using seismic and geological data.
3. Delimitation of resistive targets, and assignment of the initial model parameters of background and targets for the EM datum inversion, based on the real and imaginary images of CER, and structural characteristics from seismic data.
4. Inversion of MCSEM data in the domain of Complex Effective Resistivity for determining the resistivity and geometrical parameters of resistive targets. In this inversion, we use the initial model parameters, plus additional geological and geophysical information for the regularization of an optimization-problem solution.

We have validated the work flow, algorithms, and codes developed on the synthetic and experimental data. The results obtained show that the introduction of new attributes and inversion in the CER domain, and applying a resistive-target concept, have several advantage in comparison with the standard MCSEM attributes and conventional inversion in the EM-field domain. These advantages are: higher sensibility and resolution to the resistive targets, reducing the equivalence limits, and the possibility of obtaining the model parameters for the background and targets. Thus, the application of this approach allows us to enhance the MCSEM interpretation and finally, to increase the reliability of the EM marine exploration.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016