油管抗拉强度校核新方法

A New Checking Method for Tensile Strength of Tubing

对非组合油管在井筒中的受力情况进行了分析，主要考虑了油管的自重和浮力，推导出了计算油管最大下入深度的理论计算公式。然后，用反证法对浮力的影响能力进行了探讨，实例计算表明，忽略浮力将带来约11％的相对误差．故浮力对油管最大下入深度是不能忽略的。此外，对相对误差进行了深入研究，并得到了另外两个更易于现场应用的新公式。最后，在现场排液管柱优选中利用新公式进行了油管抗拉强度校核和实例计算及验证。计算表明，新公式可以通过油管的抗拉强度校核来为油管的优选提供理论依据，适用于中深井或新区块中增产措施、排液作业、生产以及注水过程中油管尺寸、钢级等的优选，具有较强的适用性。

The stress of non-combined oil pipe inside the borehole is analyzed. Theoretical formula for calculating the maximum setting depth of oil tube is derived in main consideration of deadweight and buoyancy of the oil tube. Then, the influence of buoyancy is discussed with a counterevidence method. According to the calculation of a case study, the ignorance of buoyancy will produce about 11% of relative error. As a result, the buoyancy can not be ignored in calculating the maximum setting depth of oil tube. Moreover, based on in-depth research on relative error, two additional new formulas more suitable for onsite application are obtained. Finally, in the onsite selection of liquor drainage tube string, new formulas are applied to check the tensile strength of oil tube and for calculation and verification of the case studies. The calculation shows that new formulas, through the checking of tensile strength of oil tube for providing theoretical basis in the selection of oil tube, are suitable for well stimulation, fluid drainage operation, and production in mid-deep wells or new blocks, and optimization of sizes and steel grades of oil tubes used in water flooding.