Scaling, multifractality, and long-range correlations in well log data of large-scale porous media

► We have used three methods to analyze a large number of well logs in oil and gas reservoirs. ► The methods include the spectral density, multifractal random walk, and multifractal detrended fluctuation analysis. ► The well logs include gamma ray, neutron porosity, bulk density and sonic data. ► The analysis provides strong evidence for multifractality of the well logs. ► The source of multifractality of the data is identified.