基于PWD的大位移井井眼不清洁识别方法

针对大位移井由于大斜度井段长容易导致井眼不清洁的状况,提出采用井下工程参数测量仪(PWD)所获取的井下环空压力进行井眼不清洁的早期识别。首先分析了引起大位移井井眼不清洁的原因,随后指出井眼不清洁时井下环空压力变化特征,并通过实测环空压力与理论计算值之间差值识别法以及环空压力概率密度识别法进行井眼不清洁的综合识别。利用上述理论分析,编制了相应的计算程序,对某大位移井钻井实际数据进行了现场测算,根据计算出的井眼不清洁综合识别指数Ed值的大小及时采取了相应措施,证明该方法可以实现井眼不清洁的早期识别报警。

Early borehole uncleanness identification based on PWD tool in highly deviated extended-research wells

The borehole of highly deviated extended-research wells are usually caused to be unclean for the long horizontal segment and high deviation of such wells. For this reason, downhole annulus pressure originating from using PWD tools is proposed to identify the early borehole unclearness. The cause of borehole uncleanness is firstly analyzed in this paper. Later the variations of downhole annulus pressure are presented as the borehole is unclean. Comprehensive borehole uncleanness identification is carried out based on the difference identification between experimental annulus pressure and its theoretical calculation and the probability density identification of annulus pressure. According to the theoretical analysis, the relevant calculating procedure is worked out and the real data acquired from an extended-research well is calculated on the site. Relevant measures are adopted according to the general index of borehole uncleanness identification. It proves that the method is credible in early borehole uncleanness identification.