Journal of Petroleum Geology, Vol.3, No.3, pp. 333-355, 1981

©Copyright 2000 Scientific Press, Ltd.

ON THE THEORY OF GROWTH FAULTING*
PART II (b): GENESIS OF THE "UNIT"

W. Crans and G. Mandl

*This research work was carried out in the Koninklijke/Shell Exploratie en Produktie Laboratorium, Rijswijk, The Netherlands, during 1968-1972 by: Dr. W. Crans, Exploration Consultant, GeoQuest International Inc./ J. R. Butler and Company, 4605 Post Oak Place, Suite 130, Houston, Texas 77027, and Dr G. Mandl, Koninklijke/Shell, Exploratie en Produktie Laboratorium, Rijswijk, The Netherlands. Some basic features have been published previously in short notes by Crans, Mandl and Shippam (1973) and Mandl and Crans (1979).

Abstract

This paper comprises a continuation of the second section of a detailed and rigorous geomechanical analysis of the stability of overpressured, gently-sloping sediment layers presented in the Journal of Petroleum Geology 2, 3, 1980 and 3, 2, 1980. The authors continue to describe the delta model which they use to explain and permit quantitative reproduction of the main features associated with growth faulting; Part II(a) considered stress equilibrium, related stress equations, types of overpressure, the representation of the stress state in Mohr space and the plastic/elastic states of frictional materials in long, fluid-filled layers. The present article continues with the analysis, with a numerical and analytical examination of slip lines and considerations of plastic, flow and slip. Peak-strength phenomena and the effect of purely-cohesive materials on the theory conclude the paper in our next issue, together with a discussion of the behaviour of water-saturated soils (as opposed to theoretical solid material with elastic and plastic properties), and the six major conclusions which can be drawn from the work.