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

This paper presents an evaluation of two fundamentally different stres s models: an elastic model, which is based on linear transverse isotro pic elasticity, and a failure model, which is based on the concept tha t rocks are in an equilibrium state of shear failure. The models are e valuated 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 li thologies encountered. However, the failure model is more accurate for predicting stress in soft shales. An example of stress predictions ba sed on log-derived elasticity parameters that gives stress estimations comparable to core-based predictions is also shown.