A mathematical correlation of porosity and permeability for Niger Delta depobelts formation using core analysis

摘要

There has been no universal mathematical relationship developed for porosity andpermeability for Niger Delta Depobelts formation using Core Analysis. The existingmathematical relationship between porosity and permeability developed from wirelinelogs has been complex due to the incorporation of several variables. Accurateestimation of rock property from core analysis is essential and needed for efficientreservoir characterization. A common practice to draw relationship between these twoparameters (porosity & permeability) is usually graphical, for instance using picketplots for general trends in the well logs data. Trends from picket plots are mostlyexplicit and subjective, that is, limited to each well and cannot be extrapolated to fullfield if the degree of heterogeneity is significant. However, core analysis gives a betterrepresentation of the sample; therefore, developing a mathematical relationship for itbecomes necessary. Statistical methods, that is regression analysis and probabilitydistribution were developed using appropriate core data. These techniques ultimatelyhelped in developing a linear mathematical model for prediction. This work focusedon correlating porosity and permeability using data obtained from core analysis in two(2) depobelts in Niger Delta. Each depobelt had several reservoirs along with theircorresponding pressures. Also, for best estimates, semi-log graphs were used togenerate decent goodness of fits. Also, the use of residual plots was presented to dealwith outliers that normally come from heterogeneity. Conclusively, from thecorrelations generated, more precise estimates of reserves/resources and production forecast can be made.