Casing cementing with half warm-up for thermal recovery wells

摘要

Thermal recovery is a very common and effective method for producing heavy oil. Casing failure is a very serious problem in thermal recovery wells. In some oilfields, more than 95% of thermal recovery well's casing was failed due to thermal stresses. In the steam injection process, the casing is heated by steam. Change of casing temperature produces thermal stresses in the casing. The casing deforms when stresses exceed yield point of its material. If using conventional cementing technology for thermal recovery wells, the casing deforms due to thermal stresses in steam injection process. Technologies conventional used to protect the casing from failure for thermal recovery wells are ineffective theoretically. Casing cementing with half warm-up for thermal recovery wells refers to heat payzone production casing to a certain temperature and makes it expand in cement slurry solidifying period. Calculations show that casing cementing with half warm-up performs greater safety coefficient during the whole production cycle and no plastic deformation. This technology will be an important method to prolong thermal recovery well's casing life.