Response analysis and safety control of tubing vibration in HPHT and ultra-deep gas wells

Abstract

Under the condition of high pressure, high temperature(HPHT) and high yield in ultra-deep wells, the buckling deformed tubing will produce violent vibration when opening and closing the well or production fluctuation, which will make the tubing bear large periodic fluctuating load, cause the failure of tubing thread seal, form fluid leakage channel, and induce the problem of sustained casing pressure(SCP). Serious annulus pressure will lead to increased tubing leakage, casing failure or more serious consequences. In order to explore the failure process of well barrier caused by tubing vibration in HPHT and ultra-deep wells, a fluid solid coupling vibration model of tubing is established, and the coupling vibration equation is numerically solved by the characteristic line method. Finally, an example of a gas well in the west is analyzed. The calculation results show that there is an obvious Poisson coupling effect between the tubing and the gas in the pipe in well X. The axial stress of the tubing is always in an unstable pulsating alternating stress state, reciprocating vibration along the axis and gradually attenuated to stability; the closer to the wellhead, the more violent the gas fluctuation in the pipe, and the greater the axial vibration amplitude of the upper part of the tubing away from the wellhead; large vibration of tubing may induce seal failure, resulting in oil jacket connection and pressure on a annulus; finally, the allowable annulus pressure of the example well is calculated, and the annulus pressure control measures are put forward. The research results have good guiding significance for well barrier failure analysis and annulus pressure control caused by tubing vibration in HPHT ultra-deep wells.