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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.

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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.