水平陀螺仪在天然碱定向对接井中的应用

Application of horizontal gyroscope in trona directional intersecting wells

摘要:

磁导向在天然碱定向对接井水溶开采中是较成熟的对接方式，但当地层存在易被磁化的黄铁矿时，其在对接阶段会被磁化变成强磁体，一方面无磁钻具长时间暴露在强磁环境下，会使得隔磁效果下降，导致MWD方位测量产生偏差。另一方面，一旦在水平段磁中靶未能一次命中，磁场异常使得MWD磁方位测量完全失效，进行第二次中靶时侧钻缺少方位数据指导。使用水平陀螺仪，可以在造斜段就对无磁钻具进行测量，并与MWD方位数据进行校正，在水平段不依赖地磁场测方位，可以为后续钻进及侧钻二次中靶提供数据指导。在国内某天然碱对接井中，使用水平陀螺仪测井，在有强磁干扰环境下实现数口靶区宽度只有152 mm左右的对接井连通，证实了水平陀螺仪在该种工况下具有可行性与可靠性。

Abstract:

Magnetic guidance is a mature intersecting method applied in solution mining of trona via directional intersecting wells. However， when pyrite susceptible to magnetization exists in strata， the pyrite will be magnetized and turn into a strong magnetic body during the well intersection stage. On one hand， prolonged exposure of non-magnetic drill strings to strong magnetic environments degrades the magnetic shielding performance， causing azimuth errors in MWD measurement. On the other hand， if the target cannot be hit at the first attempt during magnetic target hitting in the horizontal section， magnetic anomalies will completely invalidate the magnetic azimuth measurement of MWD， and no azimuth data will be available to guide sidetracking for the second target hitting. The horizontal gyroscope can be adopted to measure non-magnetic drill strings in the deflection section and calibrate the MWD azimuth data. It determines the azimuth independent of the geomagnetic field in the horizontal section， providing data support for subsequent drilling and sidetracking for secondary target hitting. In several domestic trona intersecting wells， horizontal gyroscope logging was adopted. Well interconnection was successfully achieved for multiple intersecting wells with a target width of approximately 152 mm under strong magnetic interference. The results verify the feasibility and reliability of horizontal gyroscopes under such working conditions.