套管下入过程中最大井眼曲率计算方法研究

The Study of Maximum Hole Curvature based on Casing Tripability

为明确套管下入对井眼曲率的限制,从套管弯曲截面真实的轴向力出发对弯曲段套管进行受力分析井眼曲率的选择对定向井轨道设计至为关键,其大小受制于多种条件;基于API计算最大井眼曲率传统公式的推导过程明确其适用范围及不足;对其他学者的相关计算模型的优缺点进行了评述。为了提高适用性与准确性,从弯曲段套管真实受力出发,基于有效应力得出了适用于各种拉力条件下的套管下入所允许的最大井眼曲率的计算模型。并对套管下入过程中的各种工况进行分析,且分析结果认为上提套管为最危险工况,此时的最大井眼曲率为某一弯曲井段保证套管安全下入的最大井眼曲率。得出了可适用于任何拉力条件下的新的最大井眼曲率计算模型。

The axial force of the bending section is the key point to select the curvature of the wellbore for the stress analysis of the bending section casing and the design of directional well track.Its size is subject to a variety of conditions.The derivation of the maximum borehole curvature traditional formula is based on the API.The scope and deficiencies of its application are clarified.It makes a comment on the optimization of the calculation model of other scholars.In order to improve the applicability and accuracy,the calculation model is derived based on the effective stress of the bending segment casing and effective stress.All kinds of working conditions are analyzed in the process of casing running.The analysis results show that the top casing is the most dangerous condition.Under this condition,the maximum wellbore curvature is a certain curved section to ensure the maximum wellbore curvature under the safety of the casing.A new model of maximum borehole curvature applicable to any tension condition is obtained.