深水油气水下井口系统疲劳损伤影响因素

深水油气水下井口系统作为作业的安全屏障,长期承受由环境载荷引起的周期性疲劳载荷而产生疲劳,一旦井口发生疲劳失效将导致井喷等重大事故。通过系统总结水下井口系统疲劳损伤影响因素,定性、定量分析各种因素对水下井口疲劳损伤影响,初步探究水下井口疲劳损伤诱因的影响机理。影响水下井口系统疲劳损伤因素可分水下井口系统承受外部载荷和自身疲劳抗力,前者包括环境载荷、土壤载荷、作业环境和装备等因素,主要通过改变传递到井口系统动载荷和导管、套管承受弯矩载荷改变井口疲劳损伤;后者包括井口类型选择、井口设计和导管、套管选择等因素,主要通过改变导管、套管载荷分配和承受弯矩载荷能力以及井口系统承受动载荷能力对井口疲劳损伤产生影响。其中,环境载荷、防喷器尺寸重量、井口类型以及焊接质量和位置等是影响井口疲劳损伤的关键因素。

Influencing factors for fatigue damage of underwater wellhead system of deepwater oil and gas

As a safety barrier for operations, the underwater wellhead system of deepwater oil and gas bears the cyclic fatigue loads caused by environmental loading for a long time. Once fatigue failure occurs at the wellhead, major accidents such as blowout will occur. This paper systematically summarizes the influencing factors for fatigue damage of the underwater wellhead system, qualitatively and quantitatively analyzes the effects of various factors on the fatigue damage of underwater wellhead, and preliminary explores the influence mechanism of incentives for the fatigue damage of underwater wellhead. Factors impacting fatigue damage of the underwater wellhead system can be divided into the external load borne by the underwater wellhead system and its fatigue resistance. The former includes the factors such as environmental loading, soil load,operational environment and equipment, which mainly changes the fatigue damage of wellhead by changing the dynamic load transmitted to the wellhead system and the bending moment loadings borne by the conductor and the casing. The latter involves such factors as wellhead type, the design of wellhead, as well as conductor pipes and casings, which mainly affect the fatigue damage of wellhead by changing the load distribution of conductor pipes and casings and the ability to bear bending moment loadings and the ability of the wellhead system to bear dynamic loads. In these factors, the environmental loads, size and weight of blowout preventer, wellhead type, welding quality and position are key factors affecting the fatigue damage of wellhead.