Casing Temperature and Stress Analysis in Steam-Injection Wells

摘要

For steam injection parameters of greater than 700 psi and 500rndeg F, a high production casing failure rate is often observed.rnThis is due to severe thermal stress condition to the productionrncasing string. The production casing may easily be inrncompression hot-yield under these conditions. This can lead tornhigh casing failure risk in the forms of excessive deformation,rnbuckling, and collapse. This paper presents an analysis onrncasing and cement stresses under the stated steam injectionrnconditions. The interaction of casing-cement-formation isrnconsidered to help understand casing and cement failurernmechanisms and potential approaches to reduce casing failuresrnin cyclic steam frac wells. The loss of cement integrity andrnsupport to production casing string may occur under steamrninjection condition, which attributes to casing failures in thernforms of excessive deformation, buckling, and collapse.rnField surveyed temperature in a cyclic steam frac well is alsornpresented and compared with modeled casing temperatures tornshow the needs of correctly modeling casing temperatures.rnRecent casing design practices in some Bakersfield area cyclicrnsteam frac projects, including the successful use of highrnstrength grade casing such as P-110, are discussed in order tornreduce casing failures in the cyclic steam frac wells.