IN-SITU STRESS AND ROCK STRENGTH IN THE GBRN DOE PATHFINDER WELL, SOUTH EUGENE ISLAND, GULF-OF-MEXICO/

We present a relatively simple technique to constrain in-situ stress a nd effective rock strength from observations of wellbore failure in in clined wells. Application of this technique in the Global Basins Resea rch Network (GBRN)/DOE ''Pathfinder'' well demonstrated that (1) the a zimuth of S-hmin is approximate to N42 degrees E, perpendicular to a m ajor growth fault penetrated by the well; (2) the magnitude of S-Hmax is relatively close to the vertical stress; and (3) the effective in-s itu compressive rock strength is 3,500 to 4,000 psi. We show that once we have estimated in-situ stress and rock strength, it is possible to compute the mud pressure required to inhibit failure for wells of any azimuth and inclination. Finally, we show how it is possible to estim ate the magnitudes of both S-hmin and S-Hmax in cases where independen t knowledge of stress orientation is available (for example, from well bore breakouts in nearby vertical boreholes).