Analysis of errors in historical use of Archie’s parameters

While it is common knowledge that the values of Archie’s parameters ‘a’, ‘m’ and ‘n’ may vary for sandstone reservoirs at different conditions – consolidated/unconsolidated, water-wet/oil-wet, pore geometry, degree of sphericity, clay content and in-situ depositional environment – the values of a=1, m=2 and n=2 has been linked historically with Archie’s equations. Statistically, these values were assumed as the population mean when used in calculations but the magnitude of errors associated with their use is often neglected. This study shows how a sample of data drawn from experimental and analytical methods of determining Archie’s parameters and well log from a sandstone reservoir are used to draw statistical inference about the population characteristics of Archie’s parameters in sandstone reservoirs and shows the magnitude of relative error possible when m=2 and n=2 is used to compute water saturation and formation resistivity factor.