TLP井口倾斜条件下锥形应力节可靠性评估

Reliability Assessment of Tapered Stress Joint under Inclined Wellhead of TLP

为了研究不同随机变量对锥形应力节强度可靠性的影响程度,提出了基于Kriging模型的可靠度计算方法,以深水张力腿平台立管系统中锥形应力节在实际作业工况下的响应为基础,考虑环境因素、作业因素及结构因素的随机性,以海流、张力比、材料及尺寸参数作为随机变量,建立了不同井口倾斜角度下锥形应力节的极限状态方程,分析了井口倾斜角度与锥形应力节强度及可靠性之间的关系。分析结果表明:随着井口倾斜角度的不断增大,结构应力最大值不断增大,但均未超出材料的屈服强度;随着井口倾斜角度的增大,结构失效概率不断增大,在作业过程中应控制井口的倾斜角度;在不考虑环境和作业因素随机性的情况下进行锥形应力节可靠度评估会造成失效概率明显降低,环境因素对可靠性结果的影响相对更大。研究结果可为TLP特殊钻完井作业装备的设计和安全作业提供技术支持和保障。

To study the influence of random variables on the reliability of tapered stress joint strength,a reliability calculation method based on Kriging model is proposed. Taking the actual response of the tapered stress joint in the riser system of deep water TLP as study object,considering the randomness of environmental factors,operational factors and structural factors,the limit state equations of tapered stress joints under different wellhead inclination angles are established by taking the current,tension ratio,material and size parameters as random variables.The relationships between the wellhead inclination angle and the strength and reliability of the tapered stress joint are analyzed. The analysis results show that with the increase of wellhead inclination angle,the maximum structural stress increases continuously,but do not exceed the yield strength of the material. As the wellhead inclination angle increases,the probability of structural failure increases continuously during operation. The wellhead inclination angle should be controlled during operation. The reliability evaluation of the tapered stress joint without considering the randomness of the environment and operation factors will result in significantly reduced failure probability. The influence of environmental factors on the reliability is relatively greater. The study can provide technical support and guarantee for the design and safe operation of special drilling and completion equipment on TLP.