大位移井井眼清洁监测技术

大位移井因其大斜度段和水平段长,容易造成岩屑在环空中滞留或形成岩屑床。研究表明,利用环空压力变化可以有效监测井眼清洁程度。在钻头附近安装环空压力传感器,能够精确测量环空压力,但成本高,故障率高,大范围的应用受到限制。介绍了一种方法,可根据地面立压值来计算出环空压力,监测井眼不清洁的程度。其原理是:环空压力等于立管压力减去钻柱、井下动力钻具、MWD与钻头循环压降。井下动力钻具、MWD与钻头循环压降的计算是在假定井眼为清洁的情况下,通过立压、环空循环压降、钻柱与钻头压降等计算后获得。之后,将环空压力转换成循环钻井液当量密度,据此可以监测井眼清洁程度,为大位移井安全钻井提供了一定的依据。

Hole Cleaning Detecting Method for Extended Reach Wells by Monitoring Annulus Pressure Change

Hole cleaning Detecting is vitally important in the drilling of directional and extended-reach wells. Experimental and theoretical research has improved that hole cleaning detecting is efficient by monitoring annular pressure change. Traditional methods used to determine the change of the annular pressure through measuring static bottom hole pressure using sensor near the bit do not work well for this purpose because of its high cost and high failure in hole. This paper presents a new and economical method to calculate annulus pressure by measured standpipe pressure and the pressure drop of the bottom hole assemble calculated by some models. Examples are presented that represent actual field cases and demonstrate the advantages of using the advanced method compared to conventional methods of estimating hole cleaning in Bohai Oilfield.