Method for calculating four-way safety evaluation of well oil pipe head with crack defect

A calculation method and tubing head technology are applied in the field of safety assessment and calculation of structural parts of wellhead devices containing defects, which can solve the problems of limited application scope, safety check evaluation of structural parts that cannot bear pressure, insufficient accuracy and reliability, etc. The effect of improving the degree of fit and evaluating the results is safe and reasonable

Pending Publication Date: 2018-07-06
CHINA PETROLEUM & CHEM CORP +1
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0029] The "GB / T 19624-2004 Safety Assessment of In-service Pressure Vessels with Defects" in the above (1) is only applicable to the safety assessment of pressure vessels with defects with relatively standardized dimensions. , this method is unable to check and evaluate the safety of pressure-bearing structural parts with complex structures such as wellhead devices with defects
[0030] (2) The existing standards for rejecting the structural parts of the wellhead device have a certain degree of experience, and the safety assessment is based on the appearance and use history of the equipment, and the accuracy and reliability of the rejecting judgment are not enough.
[0031] (3) Chen Xuedong and others proposed a safety assessment method for high-temperature pressure pipelines containing cracks, which is only applicable to the safety assessment of cracks in high-temperature pipelines, and has a limited scope of application, and is not applicable to the relevant wellhead device structural parts involved in the present invention

Method used

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  • Method for calculating four-way safety evaluation of well oil pipe head with crack defect
  • Method for calculating four-way safety evaluation of well oil pipe head with crack defect
  • Method for calculating four-way safety evaluation of well oil pipe head with crack defect

Examples

Experimental program
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Effect test

Embodiment 1

[0063] refer to Figure 3-Figure 7 , a method for calculating the safety assessment of a wellhead tubing head spool with crack defects, comprising the following steps:

[0064] (1) Determine the geometric dimensions of the oil pipe head spool, standardize the defects according to the actual position, shape and size of the crack, and obtain the corresponding characteristic crack size a, c, and the crack is equivalent to the major semi-axis c, short A semi-elliptical crack with semi-axis a.

[0065] (2) Determine the relevant material parameters of the tubing head, including: elastic modulus E, Poisson's ratio υ, yield strength σ s , tensile strength σ b , Fracture toughness J IC ;

[0066] (3) Finite element simulation: use the finite element software ABAQUS to establish the finite element model of the tubing head spool; image 3 shown. Wherein, the first longitudinal plane D and the second longitudinal plane H extend along the Y direction, the transverse plane I extends ...

Embodiment 2

[0080] Others are the same as in Example 1, the difference lies in the corresponding stress intensity factor in step (6) K I Fracture toughness of materials used for evaluation K C After comparison, ifK I = K C , the critical size of the crack defect can be obtained, if K I ≠ K C , finite element modeling and re-preset crack defects.

[0081] The first longitudinal plane D and the second longitudinal plane H are longitudinal sections along the Y direction at the longitudinal outlet of the oil pipe head spool. The transverse plane I is the cross section along the X direction at the transverse outlet of the oil pipe head spool.

[0082] (1) For components with discontinuous local structures such as spools with oil pipe heads, the defect evaluation method in the standard "GB / T 19624-2004 Safety Evaluation of Pressure Vessels with Defects in Service" is not applicable to them. The present invention proposes A calculation method for evaluating the safety of a cracked t...

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Abstract

The invention discloses a method for calculating four-way safety evaluation of a well oil pipe head with a crack defect, which can correspond to the influence of stress distribution of the oil pipe head under the constraint conditions generated by different component modes, the degree of coincidence between finite element modeling calculating value of the four-way stress distribution of the oil pipe head and the stress distribution of the actual member are improved, so that the safety evaluation of the four-way joint of the oil pipe with the crack defect can be more accurately judged, and thecritical safety dimension of the oil pipe head four-way can be accurately judged. In the process of evaluating the crack defect, the maximum principal stress is used to replace the vertical tensile stress of the crack surface to calculate the stress intensity factor, and the evaluation result is more safe and reasonable, so that the obtained critical safety dimension of the crack is more practicalin engineering application.

Description

technical field [0001] The invention relates to the field of safety assessment and calculation of structural parts of wellhead devices with defects, in particular to a method for calculating the safety assessment of wellhead tubing head spools with cracks and defects. Background technique [0002] At present, the wellhead tubing head spool is one of the core components in the oil production system, and plays a vital role in the safe production of oil wells. During use, due to corrosion, particle wear, medium erosion collision, abnormal pressure and other factors, defects such as cracks and wall thickness reduction will occur on the inner and outer walls, causing safety hazards in the operation of the device. If the over-standard crack defects inside and outside the casing of the wellhead tubing head spool exist for a long time and expand day by day, it will inevitably cause the casing to crack suddenly in a certain working state, or even explode, endangering personal and pro...

Claims

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Application Information

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IPC IPC(8): G06F17/50
CPCG06F30/23
Inventor 李风郑召斌冷传基郭志永
Owner CHINA PETROLEUM & CHEM CORP
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