【摘要】：定向井的鉆井作業(yè)中,受到最大拉力的井口附近以及交變彎矩作用的造斜段是鉆桿發(fā)生斷裂的危險(xiǎn)范圍;接頭螺紋及加厚過(guò)渡段的截面形狀變化比較大,結(jié)構(gòu)復(fù)雜,是疲勞裂紋產(chǎn)生的最主要的區(qū)域。以API NC50鉆桿接頭為例,建立了公螺紋根部含半橢圓表面裂紋的接頭有限元模型,通過(guò)研究拉力、彎矩分別作用下裂紋前緣的斷裂性能發(fā)現(xiàn):公螺紋中完整嚙合第一扣的根部最容易產(chǎn)生疲勞裂紋;拉力作用下量綱為一的應(yīng)力強(qiáng)度因子大于彎矩單獨(dú)作用的情況。另外,得到了螺紋根部裂紋擴(kuò)展至不同深度的臨界形狀比,擬合出拉力和彎矩分別作用下量綱為一的應(yīng)力強(qiáng)度因子隨著裂紋擴(kuò)展的變化規(guī)律,為研究位于井口附近以及造斜段的鉆桿接頭螺紋的疲勞壽命提供依據(jù)。
[Abstract]:In the drilling operation of directional wells, the dangerous range of drill pipe fracture is near the wellhead subjected to the maximum tensile force and the diagonal section under the action of alternating bending moment. The cross section shape of joint thread and thickening transition section changes greatly and the structure is complex, which is the most important area of fatigue crack generation. Taking the API NC50 drill pipe joint as an example, a finite element model of the joint with semi-elliptical surface cracks at the root of the common thread is established. The fracture behavior of the front edge of the crack under the action of bending moment respectively shows that fatigue crack is most likely to occur in the root of the first buckle of the complete meshing in the common thread; The stress intensity factor of dimension one is greater than that of bending moment under the action of tensile force. In addition, the critical shape ratio of root crack propagation to different depth is obtained, and the variation law of stress intensity factor with dimension one under the action of tension and bending moment is fitted. It provides a basis for studying the fatigue life of drill pipe joint thread located near the well head and in the inclined section.
【作者單位】： 西南石油大學(xué)機(jī)電工程學(xué)院;
【基金】：國(guó)家自然科學(xué)基金(51134004;11102173) 石油天然氣裝備教育部重點(diǎn)實(shí)驗(yàn)室資助項(xiàng)目(OGE201403-10) 西南石油大學(xué)研究生創(chuàng)新基金(CX2014SY28)
【分類(lèi)號(hào)】：O346.1
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本文編號(hào)：2326868