METHOD OF MAINTAINING THE INTEGRITY OF A SEAL-FORMING SHEATH, IN PARTICULAR A WELL CEMENTING SHEATH

摘要

A method of maintaining the integrity of a sheath, in particular a cementing sheath in a well consists in calculating or estimating variations in well pressure and/or in well temperature and/or in the variations in in-situ stresses, which may occur during the lifetime of the well, evaluating the stresses in the sheath as a function of the above variations, determining the nature of the stress likely to be first in causing deterioration of the sheath, and the risk thereof, and evaluating the influence of the elastic properties of the sheath, of the rock and/or of the casing on this stress, in order to select a sheath which is capable of attenuating this deterioration. The method is of particular application to oil, water, gas, and geothermal wells.