DIFFICULTIES IN THE USE OF DFA TO CHARACTERIZE PETROLEUM RESERVOIRS
In this work we have used the Detrended Fluctuation Analysis (DFA) technique to investigate an oil reservoir. The system we address here is situated at Bacia de Namorados, RJ, Brazil. The data corresponds to well logs of five geophysical variables: sonic, porosity, electrical resistivity, gamma ray and density measured in 56 wells. The objective of this work is to analyze the correlation or similarity among the DFA index of several geophysical quantities. We perform a linear correlation test to compare pairs of DFA indices of the geophysical quantities for the well logs. We have not found a major similarity among the five variables which indicates an absence of correlation for these variables. Therefore, we argue that the DFA index should be used with caution in the characterization of oil reservoirs. In this way we suggest to integrate the information of DFA of several physical quantities to adequately model this kind of system.
detrended fluctuation analysis oil reservoirs well logging hurst exponent