钻杆接头表面裂纹的断裂性能研究
发布时间：2018-11-12 10:37
【摘要】：定向井的钻井作业中,受到最大拉力的井口附近以及交变弯矩作用的造斜段是钻杆发生断裂的危险范围;接头螺纹及加厚过渡段的截面形状变化比较大,结构复杂,是疲劳裂纹产生的最主要的区域。以API NC50钻杆接头为例,建立了公螺纹根部含半椭圆表面裂纹的接头有限元模型,通过研究拉力、弯矩分别作用下裂纹前缘的断裂性能发现:公螺纹中完整啮合第一扣的根部最容易产生疲劳裂纹;拉力作用下量纲为一的应力强度因子大于弯矩单独作用的情况。另外,得到了螺纹根部裂纹扩展至不同深度的临界形状比,拟合出拉力和弯矩分别作用下量纲为一的应力强度因子随着裂纹扩展的变化规律,为研究位于井口附近以及造斜段的钻杆接头螺纹的疲劳寿命提供依据。
[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.
【作者单位】： 西南石油大学机电工程学院;
【基金】：国家自然科学基金(51134004;11102173) 石油天然气装备教育部重点实验室资助项目(OGE201403-10) 西南石油大学研究生创新基金(CX2014SY28)
【分类号】：O346.1
，
本文编号：2326868
[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.
【作者单位】： 西南石油大学机电工程学院;
【基金】：国家自然科学基金(51134004;11102173) 石油天然气装备教育部重点实验室资助项目(OGE201403-10) 西南石油大学研究生创新基金(CX2014SY28)
【分类号】：O346.1
，
本文编号：2326868
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