PETROPHYSICS, VOL. 45, NO. 3 (MAY-JUNE 2004); P. 268–280; 12 FIGURES Well Log Normalization: Methods and Guidelines Daniel E. Shier1 ABSTRACT Curve normalization identifies and removes systematic ual case studies. This paper describes methods that can be errors from well log data so that reliable results may be applied generally, and provides guidelines for their use in obtained for reservoir evaluation, solving difficult corre- a variety of rock suites. Also discussed are the errors that lation and seismic modeling problems. It is especially crit- are expected for the various curve types, and suggested ical for any work involving batch-puter pro- methods for correcting them. cessing. Factors to be considered in planning a normalization The normalization equation is a function of four vari- project include the rock types paction patterns in ables, two of which are defined for each well and two of the study area, hole rugosity, curve types, and the strati- which are related to regional lithologic patterns. graphic level at which run changes take place. Guidelines Well-to-parisons are made using histograms, are provided to avoid the introduction of additional inac- crossplots, depth plots, and statistical measurements. curacies. Even with these caveats, an irreducible random Prior publications on normalization have been individ- error will remain in the data. INTRODUCTION There are various reasons for tool uracies. Wellsite Those who use well logs on a regular basis have noted tool calibration may have been ineffective or there may have been drift in tool response between calibrations. Not that curves from neighboring wells do not necessarily have all logging engineers are equally experienced and may have the same values in stratigraphic units that are believed to scaled some curves improperly or may have registered them have nearly identical properties throughout an area. This on the depth grid incorrectly. Changes in the
