Viscoelastic behavior of a casing material and its utilization in premium connections in high-temperature gas wells

Abstract

At the high or extra-high temperatures in a natural gas oilfield, where the premium connection is employed by casing, gas leakage in the wellbore is always detected after several years of gas production. As the viscoelastic material's mechanical properties change with time and temperature, the relaxation of the contact pressure on the connection sealing surface is the main reason for the gas leakage in the high-temperature gas well. In this article, tension-creep experiments were conducted. Furthermore, a constitutive model of the casing material was established by the Prony series method. Moreover, the Prony series' shift factor was calculated to study the thermo-rheological behavior of the casing material ranging from 120°C to 300°C. A linear viscoelastic model was implemented in ABAQUS, and the simulation results are compared to our experimental data to validate the methodology. Finally, the viscoelastic finite element model is applied to predict the relaxation of contact pressure on the premium connections' sealing surface versus time under different temperatures. And, the ratio of the design contact pressure and the intending gas sealing pressure is recommended for avoiding the premium connections failure in the high-temperature gas well.

Promptable model for premium connection sealing surface detection and segmentation

“…Ultrasonic testing technology in the oil premium connection tubing sealing testing proposed relatively late in time, the application of technology has just begun, research on the ultrasonic testing of oil tubing seals is relatively few. At present, the oil tubing premium connection metal-to-metal sealing and its ultrasonic testing technology mainly focuses on sealing mechanism, simulation, mechanical design and other aspects 6,7,8,9 , the oil pipe seal ultrasonic testing technology in the direction of the actual application of engineering research is less. In recent years, a small number of scholars have conducted research on the possible causes of sealing failure in premium connection.…”

Effects of Make-Up Torque on the Sealability of Sphere-Type Premium Connection for Tubing and Casing Strings

“…Kim et al analyzed the effects of stabbing flank angle, upper stabbing flank corner radius on the von Mises stress of premium connection and presented the design criteria [15]. Zhang et al adopted the viscoelastic finite element model to predict the relaxation of contact pressure on the premium connections' sealing surface versus time under different temperatures [16]. Yu et al have analyzed the effect of energy dissipation on the sealing surface of premium connections with a microslip shear layer model [17].…”