Optimization Design Method and Application of Completion String in High Temperature and High Pressure Gas Well Based on Wellbore Temperature-Pressure Effect

Based on the measured values, the yield strength attenuation law with the temperature of the 110SS and 2532-110 material tubing was obtained. Tubing and annulus temperature calculation models were established according to the law of conservation of energy, according to the volume compatibility principle, the annulus thermal expansion pressure calculation model was built caused by the temperature-pressure effect. Case study show that: the higher the gas well production is, the deeper the well is, the more obviously the yield strength of the tubing decreases; The annulus thermal expansion pressure and the annulus temperature difference increases as the increase of the formation temperature and the production, compared with the production, the annulus temperature difference and thermal expansion pressure are more sensitive to the formation temperature; When the wellbore temperature-annulus thermal expansion pressure effect is not considered, the minimum triaxial safety factor of tubing is at the wellhead. When only the annulus thermal expansion pressure is considered, the minimum triaxial safety factor of tubing is above the packer. When the yield strength attenuation and annulus thermal expansion pressure are considered, the triaxial safety factor of the tubing will be reduced; Increasing the tubing steel grades of the wellhead and downhole sections can meet the strength requirement of the whole string and the normal production plan of the gas well.