CORE-BASED PREDICTION OF LITHOLOGIC STRESS CONTRASTS IN EAST TEXAS FORMATIONS

This paper presents an evaluation of two fundamentally different stress models: an elastic model, which is based on linear transverse isotropic elasticity, and a failure model, which is based on the concept that rocks are in an equilibrium state of shear failure. The models are evaluated by using physical parameters measured on core, pore pressure, and in-situ stress data from the Gas Research Institute (GRI) Staged Field Experiments (SFE's) in east Texas. It is shown that the elastic and failure models provide satisfactory predictions for most of the lithologies encountered. However, the failure model is more accurate for predicting stress in soft shales. An example of stress predictions based on log-derived elasticity parameters that gives stress estimations comparable to core-based predictions is also shown.