Why and- When does Casing Fail in Geothermal Wells

摘要

This article describes why and when casing fails in geothermal wells by means of analytical and numerical models on an integrated casing-cement system. Casing failure by buckling is generally accepted to occur at high temperatures, but it is problematical to understand such events when cement does not allow buckling to occur. One may ask why casing fails if no buckling occurs. This article describes the basic casing mechanics of such a failure event using analytical methods and integrates the connection behavior into this modeling. By explaining how casing can collapse, it is possible to use the results to improve the design of future high temperature well casing.