高温高压深井完井射孔段套管断裂力学分析

Fracture Mechanical Analysis of Completion Perforating Casing in High Temperature and High Pressure Deep Well

高温高压深井射孔段套管在完井投产作业过程中的失稳破坏是目前迫切需要解决的难题。将射孔段套管看作带有"圆孔"形贯穿裂纹(射孔孔眼)的无限大圆柱筒壳体,根据断裂力学理论,按混合法将圆柱筒壳体的平衡方程、几何方程和物理方程加以综合,推导出了射孔段套管在内、外压联合作用下的基本方程。引入复变函数,借助贝塞尔函数乘积形式的马丢函数,采用数值法直接求解射孔段套管的基本微分方程,得到了带环向裂纹射孔段套管射孔孔眼附近的应力场和位移场,从而导出了射孔段套管拉伸应力场和弯曲应力场的应力强度因子,据此提出了射孔段套管安全评价分析的断裂判据。为高温高压深井完井射孔段套管的损伤机理和疲劳寿命分析提供理论依据和技术支持。

Instability and failure of perforating casing are the urgent problems to solve during the process of completion in high temperature and high pressure （HTHP） deep well. Perforating cas- ing was looked on as the infinite cylinder shell with a ＂hole＂ crack （perforation hole）,according to the theory of fracture mechanics, the basic equation of perforation casing in the effects of internal and external pressure was derived from equilibrium equation, geometric equation and physical e- quation by mixing method. The basic differential equation of perforating casing was directly solvedwith the numerical method and Mathieu Functions with the product form of the Bessel Functions, through introduction of a complex function. The stress field and displacement field of perforating casing with circumferential crack was gained, further, the stress intensity factor of extensional tec- tonic stress field and bending stress field of the perforating casing was derived, so the fracture cri- terion of safe assessment of perforating casing was proposed. Theoretical basis and technical sup- port were supplied for damage mechanism and fatigue life of perforating casing during the process of completion in high temperature and high pressure deep well.