A number of average compressibility values of a fractured rock in a wellbore from a depth of interest is determined, where each of the number of average compressibility values is determined according to a different average scheme. For each of the number of average compressibility values, a set of effective stresses' values based on that average compressibility value. For each determined set of stresses values, a set of mud weight window values is determined based on the set of stresses values. A mud weight for the wellbore is adjusted to be within the determined set of mud weight window.
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