定向井欠压值设计中环空压耗分析模型的建立与应用

摘要

目前的定向井环空压耗分析普遍没有考虑偏心环空及岩屑床的影响,导致实际欠压值比设计值明显偏低,直接影响了定向井欠平衡技术的实施效果.在前人研究的基础上,综合考虑斜井段偏心环空及岩屑床的影响,总结并建立了一套斜井段环空压耗分析半经验模型.实例分析表明,该模型可明显提高斜井段环空压耗计算精度,可为定向井欠压值的科学设计以及欠平衡钻进过程中井底压力的动态控制提供参考.%The effect of eccentric annulus and cuttings bed has not been considered into the present annular pressure loss analysis,and it leads to actual negative differential pressure lower than the designed value,which affect the implementation effect of underbalanced drilling.On the basis of previous researches,a semi-empirical model for analysis of annular pressure loss of deviated interval has been developed considering the effects of eccentric annulus and cuttings bed.Case study shows that the model can improve the accuracy of the annular pressure loss analysis significantly,and it is useful for the design of negative differential pressure and the dynamic control of the bottomhole pressure during underbalanced drilling.