Evaluation and analysis method for air-tight seal special thread vibration fatigue failure test

A special thread and vibration fatigue technology, which is applied in special data processing applications, instruments, electrical digital data processing, etc., to achieve the effect of ensuring safe and reliable use

Pending Publication Date: 2020-10-13
BC P INC CHINA NAT PETROLEUM CORP +1
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  • Abstract
  • Description
  • Claims
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Problems solved by technology

[0006] The technical problem to be solved by the present invention is to provide an evaluation and analysis method for the vibration fatigue failure test of the special thread of the air seal to ensure the integrity of the downhole pipe string structure and seal to solve the problems of the pipe string in the high internal pressure liquid. The thread connection failure problem in the process of fracturing and production gas recovery provides an evaluation and analysis method for the selection of oil field thread connection

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  • Evaluation and analysis method for air-tight seal special thread vibration fatigue failure test
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  • Evaluation and analysis method for air-tight seal special thread vibration fatigue failure test

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Embodiment Construction

[0043] The present invention relates to a vibration fatigue failure test evaluation and analysis method for a special airtight screw thread, comprising the following steps:

[0044] S1. Evaluation method for vibration fatigue failure test of special thread of air seal;

[0045] S101. Preparation of physical samples

[0046] The length of the sample is more than 10 times the outer diameter of the pipe to ensure effective bending vibration; a strain gauge is bonded at a distance of 70mm from the threaded connection every 90°C along the circumference to monitor the vibration and bending strain, and the surface of the coupling is encapsulated with an acceleration monitoring sensor. The measurement range of the monitoring sensor is 1 ~ 15g, where g is the acceleration of gravity.

[0047] The sample selects extreme tolerance thread with high interference make-up and stress concentration; sealing, low interference minimum torque make-up and external thread end surface grooves are p...

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Abstract

The invention discloses an evaluation and analysis method for an air-tight seal special thread vibration fatigue failure test. The evaluation and analysis method includes the steps: carrying out an evaluation method for an air-tight seal special thread vibration fatigue failure test on a physical sample; analyzing the maximum principal strain and the maximum principal stress of the thread structure and the main sealing surface in a load state according to finite elements; judging whether a material mechanical property change cyclic softening condition is met or not according to the stress state of the main sealing surface, carrying out a material cyclic stress-strain test by adopting a fatigue test axial force control method according to the maximum main stress change amplitude, and establishing a material yield strength variable function; and determining final yield strength, substituting the final yield strength into the finite element model to analyze sealing energy changes of mainseal contact pressure and length, comparing the sealing energy changes with internal pressure, determining seal integrity and thread structure fatigue failure performance, and completing air-tight seal special thread vibration fatigue failure analysis. According to the evaluation and analysis method, a basis is provided for sealing and structural integrity use and analysis and prediction of the air-tight seal special thread under the specific working condition vibration load.

Description

technical field [0001] The invention belongs to the technical field of petroleum and natural gas development, and in particular relates to a vibration fatigue failure test evaluation and analysis method of a special air-tight screw thread. Background technique [0002] Oil-casing gas-tight threaded connections are widely used in high-temperature, high-pressure, high-corrosion gas wells, and the failure of oil-casing threaded connections accounts for 90% of oil-casing failures. There are three types of oil tubing loads, static loads, dynamic loads, and thermal loads. Static load refers to the long-term axial compression, tension, internal pressure, external pressure and bending; dynamic load refers to the vibration fatigue load in the process of gas production; thermal load refers to the alternating tension and compression load caused by thermal expansion and cold contraction And the effect of high-temperature material performance degradation on the load-carrying capacity. ...

Claims

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Application Information

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IPC IPC(8): G06F30/17G06F30/23G06F119/14
CPCG06F30/17G06F30/23G06F2119/14
Inventor 王建东李玉飞张林汪传磊田涛王新虎
Owner BC P INC CHINA NAT PETROLEUM CORP
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