变压力工况下井口装置的疲劳失效演化规律研究

国家自然科学基金“过程安全跨尺度风险表征与危机预警理论研究”(51574263); 中国石油大学(北京)科研基金项目“海洋浮式设施安全风险动态多场感知与控制”(2462015YQ0403); 中国石油化工股份有限公司科学研究与技术开发项目“页岩气大规模压裂安全风险评价技术研究”(P14004)

Fatigue Failure Evolution of Wellhead under Changing Pressure Condition

In the process of large-scale shale gas fracturing,wellhead is subjected to complex and cyclical load and appears fatigue failure easily,so its fatigue life becomes the research focus.Fracturing operation condition is very complicated,and the field experiment consumes manpower and material resources.In addition,numerical solving process is also a tedious work.So it is hard to solve such a problem,and in this paper,some researches are carried out by ANSYS software and FE-SAFE platform.These are used to search the fatigue failure evolution of wellhead under the changing pressure condition.Casing head and tubing head,two major parts,are selected.Through establishing the three-dimensional model,setting boundary condition,applying condition load-pressure,this paper reveals two parts' stress and strain state and the fatigue weak points under different pressure conditions,clears the regularity and relationship-how stress,strain and fatigue life change with pressure,and then draws the relationship curves and all fatigue failure evolution graphs of wellhead under the changing pressure condition.The results show that there are linear trends between two parts' maximum stresses,maximum strains and pressure approximately.In the range of maximum allowance,two parts meet the condition requirement.