Inversion method of dent defect recovery on oil and gas pipeline

Abstract

The invention discloses an inversion method of dent defect recovery on an oil and gas pipeline. The inversion method comprises the following steps: establishing a three-dimensional model of a trace application object acting on the pipeline; setting influence factors of dent defects on the pipeline; analyzing the influence of each influence factor on the recovery of the indentation defect on the pipeline; and calculating the relationship between the recovery coefficient of the dent defect in each working condition stage and the influence factor according to the influence of each influence factor on the dent defect on the pipeline. According to the method, firstly, the influence rule of each influence factor on indentation defect recovery is analyzed based on a single-factor variable method.After that, based on an orthogonal test design method, a quantitative relational expression between each influence factor and the recovery coefficient of the pipeline in different working condition stages is obtained through nonlinear analysis fitting.

Description

technical field [0001] The invention relates to the technical field of geometric defect evaluation of oil and gas pipelines, in particular to an inversion method for recovery of dent defects on oil and gas pipelines. Background technique [0002] The dent defect refers to the deformation of the cross-section of the pipe caused by the permanent plastic deformation of the pipe wall. It is the most common geometric defect on oil and gas pipelines. Dent defects are usually caused by external loads colliding or extruding pipelines. These external loads will cause different degrees of dent defects on the surface of the pipeline, threatening the safe operation of oil and gas pipelines: some dent defects will immediately rupture, resulting in immediate failure of the pipe; other dent defects do not rupture immediately, but provide an opportunity for crack initiation, which may grow over time and eventually cause the pipe to leak; still others may be subject to alternating loads In ...

AI Technical Summary

Problems solved by technology

Dent defects are usually caused by external loads colliding or extruding pipelines. These external loads will cause different degrees of dent defects on the surface of the pipeline, threatening the safe operation of oil and gas pipelines: some dent defects will immediately rupture, resulting in immediate failure of the pipe; other dent defects do not rupture immediately, but provide an opportunity for crack initiation, which may grow over time and eventually cause the pipe to leak; still others may be subject to alternating loads In addition, some dent defects will hinder the smooth passage of the pigging device, hindering pigging and internal inspection

To sum up, if these pipe sections containing dent defects are not handled properly, it will bring difficulties to the management and monitoring of oil and gas pipelines, and may even cause serious consequences, which will bring great challenges to the normal service and monitoring of pipelines, but blindly Replacing these pipe sections with dent defects will cause unnecessary losses to pipeline operators. Therefore, it is necessary to accurately evaluate the dent defects to determine the damage degree of oil and gas pipelines, and then take appropriate repair measures based on the evaluation results

[0003] In actual engineering, due to the removal of the external load at the dent or the change of the internal operating pressure of the pipeline, the dent defect will recover to a certain extent, resulting in an increase or decrease in the depth of the dent (the main basis for evaluating the dent defect) , thus affecting the evaluation results of dent defects

For example, predicting the fatigue life of a dent pipeline requires understanding the stress behavior of the pipeline at the dent and quantifying the stress concentration factor at the dent, but the stress concentration factor is a function of the dent depth, and recovery will change the dent depth. Inaccurate prediction of fatigue life; the depth data of dent defects is usually obtained through in-pipeline inspection under the operating state of oil and gas pipelines, but the existing evaluation criteria and specifications for dent defects are based on the fact that dent defects are not in the pipeline The defect characteristics measured during pressing, the dent depth will change due to the existence of pressure difference, which will affect the subsequent evaluation of dent defects

Existing technology cannot effectively analyze the dent defect recovery of oil and gas pipelines, which will affect the evaluation results of dent defects, and thus cannot provide accurate reference for pipeline operators

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