Drilling through a salt canopy can potentially provide a faster route to reach a sub-salt objective rather than drilling through a thick, overpressured sedimentary section in a supra-salt mini-basin. However, numerous geological factors can complicate the drilling, leading to expensive sidetracking or casing operations. These factors include isolated sediment inclusions within the salt, continuous or discontinuous sediment inclusions between sutured salt bodies, rapidly creeping salt, and anomalous pressure conditions such as low fracture pressures and/or narrow pore pressure-fracture pressure differentials at the base salt exit point. Sediment inclusions may be normally pressured or overpressured, possess low fracture pressures and contain variable fluid types including tar which can result in stuck drill pipe, well control events or fluid losses. Significant drilling costs could be eliminated if these hazards could be identified and avoided in the well planning process. In this paper we discuss the potential for recent developments in seismic technology including wide azimuth acquisition, 3-D multiple attenuation, sub-salt velocity determination, pre-stack depth migration, LWD borehole seismic tools and advances in geomechanical modeling using 3-D finite element analysis to impact well planning and drilling operations. Continued investment focus on these technologies could result in mitigation or avoidance of these geological hazards and greatly increase the efficiency of drilling deep-water wells to reduce finding and development costs.
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