PSI - Issue 22

Yihua Dou et al. / Procedia Structural Integrity 22 (2019) 33–42

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Author name / Structural Integrity Procedia 00 (2019) 000 – 000

Fig. 4 full-size casing test machine

Fig. 5 sample casing patch and damage photos

2.4. Experimental results The experimental data were processed, and the strain value at the edge of perforated hole was determined by extrapolating analytic curve with the help of Newton interpolation formula. The annular and longitudinal stress concentration coefficients of the sample casing were obtained, as shown in table 3.For the sample casing, the annular and longitudinal stress concentration factors are approximately equal, about 1.20-1.30 (less than the calculation value of 3.0 in the classical formula).The sample casing 5 1/2"×9.17mmP110 casing is actually perforated the experimental well with the commonly used combination of perforating gun, the phase angle and perforations density, thus the stress concentration factor can be used as a reference for calculating the remaining strength of perforated casing. Table 3 average stress concentration factor around perforated hole of test sample sample kaxial mean kannular mean TG1 1.33 1.38 TG2 1.18 1.26 TG3 1.27 1.33 average 1.26 1.32 3. Finite element analysis of stress concentration around perforations In order to verify the experimental results of stress concentration of perforated casing, finite element analysis was carried out with ANSYS software. The casing material parameters are: elastic modulus E=200GPa; Poison ratio μ=0.3; σs=758MPa . The element used is 4-node plastic large-strain shell element. In the elastic deformation range, the stress of casing increases linearly with the external load. Therefore, for the same perforated casing model, the stress concentration factor of the hole can be determined by calculating only one load condition. The finite element analysis results listed below are the calculation results under the axial tension of 300kN.