特深井高温环境下V150钻杆弹性模量和屈服强度变化规律

Variation laws of elastic modulus and yield strength of V150 drill pipe under high-temperature environment of ultra-deep well

摘要:

针对特深井钻井中高温导致钻柱强度与刚度衰减、进而影响钻具安全与井斜控制的问题，通过高温拉伸与热膨胀实验，获得了V150钢级钻杆材料在不同温度下的弹性模量与屈服强度，建立了其随温度变化的数学模型；结合经实测数据校正的井筒瞬态温度场模型，分析某特深井全井筒温度分布；综合材料模型与温度场模型，系统研究地温梯度、钻井液排量、钻井液密度及入口温度等参数对钻杆性能的影响。结果表明：V150钻杆的弹性模量与屈服强度随温度升高显著降低，在250 ℃时屈服强度衰减约15%，常规钻柱设计模型未考虑高温效应，会高估钻具实际强度；各参数对屈服强度敏感性指数的影响排序为入口温度>钻井液排量>地温梯度>钻井液密度，对弹性模量敏感性指数的影响排序为地温梯度>钻井液密度>入口温度>钻井液排量；特深井钻柱设计必须考虑高温导致的性能衰减，可通过优化排量与入口温度提升钻柱安全性。研究成果为特深井钻柱设计与施工提供了技术支撑。

Abstract:

To address the issue of strength and stiffness degradation of drill strings under high-temperature conditions in ultra-deep well drilling， which affects drillstring safety and deviation control， high-temperature tensile and thermal expansion tests were conducted on V150-grade drill pipe material. The elastic modulus and yield strength at different temperatures were obtained， and a mathematical model describing their variation with temperature was established. Combined with a transient wellbore temperature field model calibrated with measured data， the temperature distribution along a specific ultra-deep well was analyzed. Integrating the material model and the temperature field model， the effects of parameters such as geothermal gradient， drilling fluid flow rate， drilling fluid density， and inlet temperature on drill pipe performance were systematically investigated. The results show that both the elastic modulus and yield strength of V150 drill pipe decrease significantly with increasing temperature， with the yield strength decreasing by approximately 15% at 250 ℃. Conventional design models， which do not account for this temperature effect， overestimate the actual strength of the drill string. The sensitivity indices of the parameters affecting yield strength follow the order： inlet temperature > drilling fluid flow rate > geothermal gradient > drilling fluid density， while for elastic modulus the order is： geothermal gradient > drilling fluid density > inlet temperature > drilling fluid flow rate. The design of drill strings for ultra-deep wells must consider performance degradation due to high temperatures， and safety can be enhanced by optimizing flow rate and inlet temperature. The research findings provide technical support for the design and operation of drill strings in ultra-deep wells.