Limits...
Burst strength of tubing and casing based on twin shear unified strength theory.

Lin Y, Deng K, Sun Y, Zeng D, Liu W, Kong X, Singh A - PLoS ONE (2014)

Bottom Line: Also, the practical safety coefficient of some wells is lower than the design standard according to the current API 5C3 standard, which brings some perplexity to the design.Numerical and experimental comparisons show that the new burst strength model is much closer to the real burst values than that of other models.The research results provide an important reference to optimize the tubing and casing design of deep and ultra-deep wells.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Southwest Petroleum University), Chengdu, Sichuan, 610500, China.

ABSTRACT
The internal pressure strength of tubing and casing often cannot satisfy the design requirements in high pressure, high temperature and high H2S gas wells. Also, the practical safety coefficient of some wells is lower than the design standard according to the current API 5C3 standard, which brings some perplexity to the design. The ISO 10400: 2007 provides the model which can calculate the burst strength of tubing and casing better than API 5C3 standard, but the calculation accuracy is not desirable because about 50 percent predictive values are remarkably higher than real burst values. So, for the sake of improving strength design of tubing and casing, this paper deduces the plastic limit pressure of tubing and casing under internal pressure by applying the twin shear unified strength theory. According to the research of the influence rule of yield-to-tensile strength ratio and mechanical properties on the burst strength of tubing and casing, the more precise calculation model of tubing-casing's burst strength has been established with material hardening and intermediate principal stress. Numerical and experimental comparisons show that the new burst strength model is much closer to the real burst values than that of other models. The research results provide an important reference to optimize the tubing and casing design of deep and ultra-deep wells.

Show MeSH
Elastic region (Outer cylinder).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4232241&req=5

pone-0111426-g002: Elastic region (Outer cylinder).

Mentions: The interface between the elastic region and plastic region is cylinder surface due to the axial symmetry of stress components (σθ and σr). Assume that the elastic region is an outer cylinder, as shown in Figure 2, and the plastic region is an inner cylinder, as shown in Figure 3. Therefore, the elastic and plastic regions are analyzed based on the principle of long thick-walled cylinder. According to axial symmetry, the radial pressure (q) is applied to outer wall of inner cylinder and inner wall of outer cylinder respectively, as shown in Figure 2 and Figure 3.


Burst strength of tubing and casing based on twin shear unified strength theory.

Lin Y, Deng K, Sun Y, Zeng D, Liu W, Kong X, Singh A - PLoS ONE (2014)

Elastic region (Outer cylinder).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4232241&req=5

pone-0111426-g002: Elastic region (Outer cylinder).
Mentions: The interface between the elastic region and plastic region is cylinder surface due to the axial symmetry of stress components (σθ and σr). Assume that the elastic region is an outer cylinder, as shown in Figure 2, and the plastic region is an inner cylinder, as shown in Figure 3. Therefore, the elastic and plastic regions are analyzed based on the principle of long thick-walled cylinder. According to axial symmetry, the radial pressure (q) is applied to outer wall of inner cylinder and inner wall of outer cylinder respectively, as shown in Figure 2 and Figure 3.

Bottom Line: Also, the practical safety coefficient of some wells is lower than the design standard according to the current API 5C3 standard, which brings some perplexity to the design.Numerical and experimental comparisons show that the new burst strength model is much closer to the real burst values than that of other models.The research results provide an important reference to optimize the tubing and casing design of deep and ultra-deep wells.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Southwest Petroleum University), Chengdu, Sichuan, 610500, China.

ABSTRACT
The internal pressure strength of tubing and casing often cannot satisfy the design requirements in high pressure, high temperature and high H2S gas wells. Also, the practical safety coefficient of some wells is lower than the design standard according to the current API 5C3 standard, which brings some perplexity to the design. The ISO 10400: 2007 provides the model which can calculate the burst strength of tubing and casing better than API 5C3 standard, but the calculation accuracy is not desirable because about 50 percent predictive values are remarkably higher than real burst values. So, for the sake of improving strength design of tubing and casing, this paper deduces the plastic limit pressure of tubing and casing under internal pressure by applying the twin shear unified strength theory. According to the research of the influence rule of yield-to-tensile strength ratio and mechanical properties on the burst strength of tubing and casing, the more precise calculation model of tubing-casing's burst strength has been established with material hardening and intermediate principal stress. Numerical and experimental comparisons show that the new burst strength model is much closer to the real burst values than that of other models. The research results provide an important reference to optimize the tubing and casing design of deep and ultra-deep wells.

Show MeSH