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Chapter from:
AAPG Memoir 71 : Reservoir Characterization-Recent Advances
Edited by Richard A. Schatzinger and John F. Jordan
Copyright 
1999 by The American Association of
Petroleum Geologists. All rights reserved.
Memoir 71, Chapter 6: Petrofacies Analysis--A Petrophysical Tool for Geologic/Engineering
Reservoir Characterization, by W. L. Watney, W. J. Guy, J. H. Doveton, S. Bhattacharya,
P. M. Gerlach, G. C. Bohling, and T. R. Carr , Pages 73 - 90
Chapter 6
Petrofacies Analysis--A Petrophysical Tool for
Geologic/Engineering Reservoir Characterization
W. L. Watney
W. J. Guy
J. H. Doveton
S. Bhattacharya
P. M. Gerlach
G. C. Bohling
T. R. Carr
Kansas Geological Survey
Lawrence, Kansas, U.S.A.
ABSTRACT
Petrofacies analysis is defined as the characterization and classification of pore
types and fluid saturations as revealed by petrophysical measurements of a reservoir. The
word "petrofacies" makes an explicit link between petroleum engineers' concerns
with pore characteristics as arbiters of production performance and the facies paradigm of
geologists as a methodology for genetic understanding and prediction. In petrofacies
analysis, the porosity and resistivity axes of the classical Pickett plot are used to map
water saturation, bulk volume water, and estimated permeability, as well as capillary
pressure information where it is available. When data points are connected in order of
depth within a reservoir, the characteristic patterns reflect reservoir rock character and
its interplay with the hydrocarbon column. A third variable can be presented at each point
on the crossplot by assigning a color scale that is based on other well logs, often gamma
ray or photoelectric effect, or other derived variables. Contrasts between reservoir pore
types and fluid saturations are reflected in changing patterns on the crossplot and can
help discriminate and characterize reservoir heterogeneity.
