Structural Models for the Analysis of Stresses in the Casings of Geothermal Wells

Abstract

This paper illustrates an exacting work undertaken by ENEL to gain greater insight into the behavior of geothermal wells, seen as a structural element subject to and mechanical stresses. The stresses that occur in the casing in connection with temperature variations due to well operations are examined after the development of suitable structural models. These models take into account the presence of defects in the cementing of the casing annulus which are related to the way the casing has been set and cemented. Such stresses are also used as input for design and strength verifications, as well as for fatigue analysis. Finally, comparison is made with the results of statistical research on damage that has occurred in the wells drilled by ENEL in the last five years. Agreement with the conclusions drawn from the abovedefined models is excellent.