Research Article

Experimental Study on Sealing Failure Mechanism of Injection-Production String in Underground Gas Storage under Cyclic Loading

Table 3

Operation load of the injection-production tubular string.

Annulus pressure change (MPa)Operating conditionCalculation conditionMaximum load during injection (kN)Maximum load during production (kN)

Initial gas injectionEffective axial force (formula (1))733.13
Consider stress relaxation (formula (2))393.31
Consider pressure drop (formula (3))984.74
Consider stress relaxation and pressure drop (formula (5))670.63
0Gas production operationEffective axial force (formula (1))−371.68
Consider stress relaxation (formula (2))−634.19
Consider pressure drop (formula (3))−522.63
Consider stress relaxation and pressure drop (formula (5))−743.08
Gas injection operationEffective axial force (formula (1))665.12
Consider stress relaxation (formula (2))316.17
Consider pressure drop (formula (3))792.01
Consider stress relaxation and pressure drop (formula (5))468.93