重力MWD技术在国外的应用

在定向钻井中，MWD／LWD越来越显示出其优越性。与陀螺仪或单点、多点等测斜仪相比，MWD／LWD能在不影响钻进的情况下完成测量，同时提供多种井下参数，节约钻时，减少井下事故等。但是，常规MWD／LWD是一种磁力测斜仪，利用大地磁场来测量井下方位，如在靠近磁性干扰源附近测量时就出现较大的误差。介绍了一种新型的重力随钻测斜（GMWD）工具，它能够有效避免磁场干扰，在磁性环境下比较准确地获取井眼轨迹参数。结合重力测量方位角的原理，分析了重力MWD的方位角测量技术和作业中的关键影响因素，该技术在英国北海油田W1Z井中的应用表明，重力MWD能避免磁场干扰，测得的方位角精度较高。

The Application of Gravity MWD Technique in Foreign Countries

The performance of MWD/LWD(measurement while drilling/ logging while drilling) are becoming more and more superiority in directional drilling.Compared to gyro multishot,single shot inclinometer and magnetic multishot inclinometer,using MWD/LWD the measurement can be finished without impacting drilling operations and various downhole parameters can be provided.At the same time,the drilling time is saved and downhole accidents are reduced.Since MWD/LWD are magnetic survey tools using terrestrial magnetic field to measure azimuth,larger error will be occurred when working near a magnetic object. This paper introduced a new gravity measurement while drilling(GMWD) which can effectively avoid the magnetic field interference and obtain the accurate wellbore trajectory parameters.The azimuth measurement technique of GMWD and the key parameters in application was analyzed combined with the principles of gravity measurement.The application of this technique in Well W1Z in North Sea Oilfield indicates that GMWD could avoid magnetic inference and the measured azimuth had higher precision.