ABSTRACT
This paper presents the mathematics and procedures to determine elastic rock properties from testing cylindrical core based upon orthotropic elastic theory. It also examines the extremely non-linear, but elastic, stress strain characteristics of some sandstones and what controls their Young’s moduli and Poisson’s ratios. The effects of fluid pressure changes within the rock are also considered. Two different modes of fluid behaviour are considered. The first is associated with poroelastic behaviour, while the second is associated with the effect of fluid within fractures. The use of these parameters leads to stress distributions and deformations that vary from those arrived at using conventional, but incorrect, assumptions of rock behaviour.
