نویسندگان | Z. Koohi, S.Vasheghani Farahani, G.R.Jafari |
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نشریه | Physica A |
ضریب تاثیر (IF) | 2.5 |
نوع مقاله | Full Paper |
تاریخ انتشار | November 2012 |
رتبه نشریه | ISI |
نوع نشریه | چاپی |
کشور محل چاپ | هلند |
نمایه نشریه | Q2 |
چکیده مقاله
Geological systems such as petroleum reservoirs can be investigated using Tsallis entropy and multiplicative hierarchical cascade models. The occurrence of non-Gaussianity is a sign of uncertainty and a phase transition, which could indicate the existence of a petroleum reservoir. Two important parameters that describe a system at any scale are determined: the degree of non-Gaussianity, q, for the entropy and the intermittency, λ2, which explains critical behavior in a system. Some petrophysical indicators can be used to characterize a reservoir, but there is a lack of methods for measuring scaling information. This study compares non-Gaussianity for three selected indicators at various scales: gamma radiation (GR), sonic transient time (DT) and neutron porosity (NPHI). The results show that GR has a fat-tailed probability distribution function (PDF) at all scales, which is a sign of phase transition in the system and indicates high q and λ2. This provides valuable information about GR. NPHI shows scale dependence and the PDF converges to a Gaussian distribution at large scales. This is indicative of separated and uncorrelated porosity at large scales. For the DT series, small λ2 and q at all scales are a hallmark of local DT correlations.