渤海油田A15井误射孔影响因素分析

Analysis of the Perforation Complicated Situation for A15 Well in Bohai Oilfield

误射孔事故作为典型的钻完井事故,耗费巨大的人力、财力和时间。渤海油田A15井在射孔作业施工过程中出现了复杂情况,导致射孔管柱从安全接头处脱手落井,打捞后发现射孔枪提前引爆出现误射孔。为分析误射孔时间及影响因素,本文运用水动力学原理模拟进行计算研究,查明原因并对后续作业进行指导。结果表明,A15井在第二次打捞射孔管柱时引发误射孔事故,由于震击产生的波动压力与静液柱压力之和大于剪切销材料的屈服强度,多次震击引起剪切销钉疲劳破坏;同时震击瞬时速度产生的波动压力也对剪切销钉造成损坏,双重作用下导致打捞管柱时射孔枪起爆。为避免出现类似状况,建议深井和复杂井射孔作业时使用压差点火头替代全压力点火头;若使用压力点火头,应尽可能提高点火压力,保证射孔施工的安全。

The mistaking perforation accident is typical drilling accident, dealing with which will consume huge manpower, financial resources and time. It was occurred a complicated situation when perforating operation was performed in A15 well when the perforating string below the safety joint was dropped out in the well. After fishing the string, it was discovered that the perforator detonated at the wrong depth in the well. In order to analyze the time of mistaking perforation and the influencing factors, hydrodynamic principles are used to calculate and research to identify the causes and guide the follow-up work. It shows that mistaking perforation occurred when the second fishing string. Because the sum of fluctuation pressure caused by jar and hydrostatic pressure is greater than the yield strength of shearing material, multiple shocks finally leads material fatigue. In the meantime, fluctuation pressure caused by instantaneous speed brings about damage. The phenomenon of mistaking perforation is arose from both two factors. In order to avoid the similar situation, it is suggested that differential pressure ignition head should be used instead of the full pressure ignition head at the situation of deep wells and complex wells. If full pressure ignition head is necessary, the ignition pressure should be improved as much as possible to ensure the safety of perforation.