Wellbore stress distribution produced by moisture adsorption

The objective of this study is to evaluate the stress distribution produced by moisture adsorption around a wellbore by applying the mechanics of deformable solids. This paper shows that the moisture adsorption process is governed by a diffusion equation, and that the equations governing the moisture induced stresses around the hole are similar to those equations in thermoelasticity. A computational method is thus developed for calculating the stress distribution around the borehole. The experimental procedure for obtaining the material constants needed in the computation are also presented and demonstrated. The effect of borehole pressure on the stress distribution around the hole is also studied. The results show that the magnitude and distribution of stresses around the borehole are very sensitive to the adsorption characteristics and the moisture induced modulus change of the material.