Study of Temperature Effect on the High Performance of OCTG Used for Deep and Ultra-Deep Well

Abstract

With the exploitation of deep well, ultra-deep well, thermal recovery Well and Geothermal Well, the temperature of tubing and casing is increasing constantly. The influence degree of temperature on tubing and casing material performance has attracted much attention in the design of tubular strings. The experimental study on the yield strength and tensile strength of tubular materials with temperature change is carried out, which includes C110, 140ksi, P110 and S13Cr110. In this paper, the yield strength correction coefficient of tubular material is defined, and the material performance model of different steel grade tubular material with temperature change is established. The paper describes the influence of underground high temperature on the design of tubular strings and shows that the yield strength of tubular material will decrease under high temperature. This directly affects the safety parameter of tubing and casing design, and greatly impact on the safety reliability and service life of the tubular strings. This paper points out the defects which exist in the current API formulas, when calculating the force of the tubular string. It is suggested that the yield strength at high temperature should be used as the design basis for deep well and ultra-deep well when the underground temperature is high. The results can be used to guide the design and check of tubular strings under high temperature and high-pressure gas well.Keywords:deep and ultra-deep well; special performance tubing and casing; high temperature; yield strength; tubular strings integrity;OCTG