The drilling of wells and production of hydrocarbons lead to changes in the stresses acting on the reservoir and surrounding rocks, and these changes in stress may lead to problems such as wellbore instability, sanding, loss of permeability, reservoir compaction, casing deformation, surface subsidence, etc. Elastic-wave velocities in sandstones are sensitive to changes in stress due to the presence of grain boundaries and microcracks within the rock. This paper shows how changes in elastic-wave velocities can be used to monitor the changes in stress that occur, and a method for predicting the velocity changes due to a given change in stress is illustrated using the example of a borehole drilled into a sandstone reservoir.

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