This paper presents the results of laboratory static and dynamic tests on casing-cement-rock systems exposed to axial loads under ambient conditions. A new testing method has been developed.

The casing-cement-rock system mostly fails due to tension and shear stresses. In various applications such as HPHT, deep-water, (steam) injection or geothermal wells, the cement-casing bond is exposed to cyclic thermomechanical loads resulting in casing elongation, contraction, expansion and subsequently in cyclic radial and axial stresses at the cement-casing-rock system. Cement is a brittle material which can fail when subjected to repeated application of stresses lesser in magnitude than the statically determined strength. A novel atmospheric test cell has been designed and constructed. In order to achieve the fatigue limits of the cement-casing bond, a set of testing procedures has been established. Several tests are conducted to evaluate de-bonding. The focus on de-bonding is achieved by allowing the casing to move through the test while preventing any cement movement. Thus, when a force is applied in the axial z-direction - either the casing is pulled out (tension) or pushed down (compression) - the casing has enough space to move in both directions. The advantage of this testing method is that different stress ratios can be applied during the test.

You can access this article if you purchase or spend a download.