三维弯曲井眼中压裂套管轴向载荷分析

Axial Load Analysis of Fracturing Casing in Three-dimensional curved Wellbore

大规模的压裂改造会导致套管处于复杂的受力状态中,严重时会出现变形、弯曲、断裂等问题。考虑井眼轨迹、套管结构、压裂施工要求,考虑套管浮容重、管内流体压力、流体摩擦阻力以及温度载荷作用,建立套管轴向载荷力学模型。计算套管所受轴向力,分析其抗拉强度,以合理选择压裂参数,预防套管损坏。以油田某井压裂施工为例,根据建立的轴向载荷力学模型,计算得三维弯曲井眼中套管的最大轴向载荷在井口位置约为2191.648k N;井口套管抗拉强度安全系数最低,约为1.408,基本满足压裂施工要求。

Large-scale fracturing transformatio n will cause the casing to be in a complex state of stress, and serious problems such as deformation, bending, and fracture will occur. In this paper, the wellhole trajectory, casing structure, and fracturing construction requirements are considered. The casing bulk density, fluid pressure in the casing, fluid friction resistance, and temperature loading are considered. A casing axial load mechanical model is established to calculate the axial force on the casing Analyze its tensile strength to reasonably select fracturing parameters to prevent casing damage. Taking the fracturing construction of a well in the oilfield as an example, according to the established axial load mechanics model, the maximum axial load of the casing in the three-dimensional curved wellbore is calculated at the wellhead position of approximately 2191.648 kN;the wellhead casing has the lowest tensile strength safety factor. About 1.408, which basically meets the requirements of fracturing construction.