In the context of oil & gas exploration and production, it is important to perform measurements in wellbore to determine, for example, well integrity including the integrity of cement within an annulus between a casing and the formation. Impedance logs are particularly useful to assess well integrity inasmuch as it provides an "Image" of the cementation quality all around the casing. The data must be processed correctly of course to give an accurate image of the cementation behind the casing. Usually, data is processed by considering that it depends on the velocity and the density. However, studies have shown that it probably also depends on the stress applied on the external part of the casing. Hence, to be able to correct data for the effect of the casing stress on the impedance values given by the impedance logs, it is important to be able to assess the stresses applied all around the casing. Unfortunately, there is no method in the literature to calculate directly the stresses on the casing.
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