發(fā)布時間：2018-01-08 08:00

  本文關(guān)鍵詞：含缺陷連續(xù)油管的疲勞壽命研究　出處：《長江大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 連續(xù)油管 缺陷 有限元法 塑性應(yīng)變 疲勞壽命

【摘要】：隨著石油產(chǎn)業(yè)的飛速發(fā)展,在油氣田的作業(yè)中,連續(xù)油管作業(yè)設(shè)備被普遍應(yīng)用,施展著越來越重要的作用。在作業(yè)時,連續(xù)油管于滾筒上反復(fù)卷繞和拉直的過程中會產(chǎn)生低周疲勞,因為連續(xù)油管滾筒和鵝頸導(dǎo)向器的曲率半徑遠(yuǎn)遠(yuǎn)小于連續(xù)油管的彈性極限半徑,所以每次彎曲拉直時都會發(fā)生塑性變形,當(dāng)塑性應(yīng)變累積到一定程度會導(dǎo)致連續(xù)油管的疲勞破壞。如果連續(xù)油管帶有缺陷,在缺陷處會產(chǎn)生應(yīng)變集中,則會加速連續(xù)油管的疲勞損傷累積,疲勞壽命就會加速縮短。如果將這些有缺陷的連續(xù)油管再次下入井內(nèi),很有可能作業(yè)不了幾次就發(fā)生連續(xù)油管的穿孔或者斷裂事故。連續(xù)油管的缺陷十分常見,為了預(yù)防在作業(yè)過程中突然斷裂而導(dǎo)致安全事故,對含缺陷連油續(xù)管的疲勞壽命要有一定的預(yù)測,快要達(dá)到壽命極限時,應(yīng)立即停止或放棄連續(xù)油管的作業(yè)。為了估算含不同形狀下的不同尺寸的缺陷的連續(xù)油管疲勞壽命以及研究缺陷對連續(xù)油管疲勞壽命的影響,本文用有限元方法分別模擬含不同尺寸橢球形缺陷、方形缺陷、球形缺陷以及圓柱形缺陷四種最常見的缺陷的連續(xù)油管在卷繞矯直過程中的變形和疲勞,并分別用等效應(yīng)變法和臨界面法估算出相應(yīng)的疲勞壽命,繪制成相應(yīng)圖表。其中橢球形缺陷和方形缺陷的尺寸包括其余方向上尺寸不變情況下的不同長度、不同深度、不同寬度。缺陷尺寸變化,疲勞壽命也會相應(yīng)變化,其中長度方向尺寸變化對連續(xù)油管疲勞壽命的影響是大于深度方向和寬度方向的影響的;在其余方向上的尺寸不變的情況下,軸向的長度越短,徑向的深度越深,環(huán)向的寬度越寬,連續(xù)油管疲勞壽命就越短。對于球形缺陷的尺寸只是半徑的變化,連續(xù)油管的疲勞壽命并不隨著半徑尺寸的變化而單調(diào)變化,而是出現(xiàn)波動。圓柱形缺陷對連續(xù)油管的疲勞壽命的影響和方形缺陷對連續(xù)油管的疲勞壽命的影響是基本上類似的和相通的。綜合起來看,四種類型缺陷對連續(xù)油管疲勞壽命的影響從大到小依次為:方形缺陷、圓柱形缺陷、球形缺陷、橢球形缺陷。缺陷曲率半徑越小的地方,應(yīng)變集中越明顯,應(yīng)變越集中,對連續(xù)油管的疲勞破壞來說,累積塑性就越快,從而疲勞壽命就越短。連續(xù)油管在卷繞矯直的過程中,在缺陷處的受力可以看做是軸向的拉伸或壓縮,缺陷尺寸在軸向縮短和在環(huán)向或者徑向增長會降低連續(xù)油管的疲勞壽命,反之亦然。
[Abstract]:With the rapid development of petroleum industry, oil and gas fields in the operation, the coiled tubing equipment is widely used, play an increasingly important role. In operation, the process of coiled tubing in the drum repeatedly winding and straightening will produce low cycle fatigue, because the elastic limit radius of curvature radius of coiled tubing and gooseneck guide roller is far less than the coiled tubing, so each bending straightened will occur when the plastic deformation, when the plastic strain accumulated to a certain extent can cause fatigue failure of coiled tubing. If the coiled tubing with defects, defects will be produced in the strain concentration will accelerate the fatigue damage accumulation of coiled tubing, the fatigue life will shorten the. If these defective coiled tubing again into the wells, is likely to work a few times on continuous tubing perforation or rupture of the coiled tubing. The defect is very common, in order to prevent sudden rupture during operation and cause accidents, even of the defective oil continued to have a certain fatigue life prediction, reaching the limit of life, should immediately stop or give up the coiled tubing homework. In order to influence fatigue life of coiled tubing in different sizes with different shapes under estimation of defects the research and the defects on the fatigue life of coiled tubing, using the finite element method is simulated respectively with different sizes of ellipsoidal defects, square defects, spherical and cylindrical defect defect of four kinds of the most common defects of coiled tubing in the winding process of straightening deformation and fatigue, and respectively with the equivalent strain and critical plane method estimate the corresponding fatigue life, drawing into the corresponding chart. The ellipsoid defects and square defects including the size of the other direction sizes of different lengths under the condition of, Different depth, different width of defect size changes, fatigue life will change accordingly, which influence the length size on the fatigue life of coiled tubing is greater than the impact of the depth and width; in the other direction the size unchanged, the axial length and radial depth of the ring. The width is, the shorter fatigue life of coiled tubing. The spherical defect size is the change of radius, fatigue life of coiled tubing does not change with the size of the radius increases monotonically, but fluctuate. Influence of fatigue life on fatigue life of cylindrical defects of coiled tubing and coiled tubing defects on the square is basically similar and interlinked. Taken together, effects of four types of defects on the fatigue life of coiled tubing from large to small is as follows: square defects, cylindrical ball defects. Ellipsoidal shape defects, defect defect. The smaller the radius of curvature, strain and strain concentration is more obvious, more concentrated, the fatigue of coiled tubing failure, accumulated plastic faster, thus the fatigue life is short. The process of coiled tubing in the winding straightening, the stress at the defect can be seen as axial tension or compression, defect size reduce the fatigue life of the coiled tubing, or to radial growth in axial shortening in the ring and vice versa.

【學(xué)位授予單位】：長江大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TE931.2

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