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Description Appraisal wells prior to field development provide the only opportunity to gather data required to maximize production through completions and reduce costs through optimized operations. Full understanding of the stress state in the earth, anisotropic rock mechanics and pore pressure is essential for safe, efficient drilling of the deviated development wells and production to their full potential. Understanding uncertainties in these parameters affects the economic production of these assets. A recent appraisal well in Hess's Bergading Field, drilled for a shallow sand, provided the opportunity to use it as a laboratory for future development. Full waveform sonic data, wellbore images, stress testing and full cores were gathered. Continuous estimates of anisotropic rock mechanical properties were compared and calibrated with core The 3 dimensional shear moduli were measured and continuous magnitudes of reservoir horizontal stress were obtained. Although the borehole itself was close to circular showing no break-out, larger than expected horizontal stresses were observed and the mini-frac failed to achieve breakdown at a pressure of 4500psi at 4000ft. State of the art sonic measurements providing shear radial-profiling from the sand-face into the far-field allowed direct derivation of horizontal stress magnitudes in the sand. These measurements also predicted a higher formation breakdown pressure than was applied in the mini-frac test. Application Well-bore stability, sanding and perforating all depend for their effective utilization on an understanding of the rock mechanics and state of stress of the material around the borehole. The horizontal stress field and the rock strength define the failure modes and predict stability and sanding behaviour in deviated wells planned for field development. Results The horizontal stresses from the sonic measurements were used to generate a revised safe drilling window for mud-weight. Subsequent core test results were able to describe plastic vs. elastic behaviour in the near-wellbore region to predict failure modes. Perforation recommendations and sanding predictions were also produced Significance Results are significant because they speak to the underlying geology of the basin, the behaviour of individual boreholes within that setting and the optimization of strategies in well, perforation and completion design, thus reducing cost and maximizing production

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