水下防喷器疲劳寿命分析及判废研究

目前,国内尚无针对水下防喷器专用的判废标准,采用通用判废指标对其进行判废,适用性较差。在分析国内外井控装备判废标准的基础上,确定了年限和承压次数为防喷器的主要判废指标。通过防喷器壳体的强度分析,基于材料的S-N疲劳曲线法,计算防喷器壳体疲劳寿命; 应用Paris公式对含裂纹缺陷防喷器壳体疲劳寿命进行分析。结果表明:防喷器壳体在额定工况下及试验工况下满足强度要求; 以疲劳理论计算出额定工作压力工况下的防喷器的承压循环次数及工作年限远大于标准中要求的指标; 含有初始裂纹防喷器壳体的疲劳寿命远小于未含有裂纹的壳体疲劳寿命,且随着初始裂纹尺寸的增加,防喷器壳体的疲劳寿命逐渐降低。通过对防喷器壳体进行疲劳寿命分析,为水下防喷器判废研究提供了一种新思路。

Research of the Fatigue Life and Abandonment Judgment of Subsea BOP

There is no specialized judgment of abandonment for subsea BOP at present,and the applicability of the common index is not good enough to be used to judge the abandonment of subsea BOP.Basic on the analysis on the abandonment judgments of well control equipment in domestic and overseas,two main indexes were confirmed in this paper for abandonment judgment of subsea BOP,they are age limit and pressure bearing number respectively.It calculated the fatigue life of subsea BOP shell on the basic of strength analysis,and moreover,it analyzed the fatigue life of subsea BOP shell which has a crack defect with the Paris equation.The result shown that the subsea BOP shell can meet the strength requirement under the certain operating conditions and the test conditions; the confining cycle times and work seniority calculated from the fatigue theory under certain working pressure are much larger than the index in the standard; the fatigue life of the subsea BOP who has an initial crack is much smaller than the one who does not has an initial crack,and also with the increase of initial crack dimension,the fatigue life will decrease gradually.It provides a new clue for the research of the judgment of abandonment of subsea BOP through the analysis of fatigue life.