Li Hongqiang, Wang Ruihe
School of Petroleum Engineering, China University of Petroleum, Qingdao 266580, China.
Sinopec Shengli Drilling Technology Research Institute, Dongying 257000, China.
Sensors (Basel). 2021 Feb 10;21(4):1258. doi: 10.3390/s21041258.
The drill string used in drilling is in a complex motion state downhole for several kilometers. The operating attitude and eccentricity of the downhole drill string play important roles in avoiding downhole risks and correcting the output of the imaging measurement sensor while drilling (IMWD). This paper proposes a method for measuring eccentricity while drilling using two sets of caliper sensors coupled with a fiber-optic gyroscope for continuous attitude measurement, which is used to solve the problem of the quantitative measurement of complex eccentricity that changes in real-time downhole. According to the measurement and calculation methods involved in this article, we performed simulations of the attitude of the drill string near where the IMWD tool is located in the wellbore under a variety of complex downhole conditions, such as centering, eccentricity, tilt, buckling, rotation, revolution, etc. The simulation and field test results prove that the distance between the imaging while drilling sensor and the borehole wall is greatly affected by the downhole attitude and revolution. The multi-sensor layout measurement scheme and the data processing based on the above-mentioned measurement involved can push the drill collar movement and eccentricity matrix specifically studied downhole from only qualitative estimation to real-time measurement and quantitative calculation. The above measurement and data processing methods can accurately measure and identify the local operating posture of the drill string where the IMWD sensor is located, and quantitatively give the eccentric distance matrix from the measuring point to the borehole wall required for environmental correction of the IMWD sensor.
钻井过程中使用的钻柱在井下数千米的复杂运动状态下工作。井下钻柱的工作姿态和偏心度对于避免井下风险以及在钻井过程中校正成像测量传感器（随钻测井仪，IMWD）的输出起着重要作用。本文提出了一种利用两组卡尺传感器与光纤陀螺仪相结合进行随钻偏心度测量的方法，用于连续姿态测量，以解决井下实时变化的复杂偏心度的定量测量问题。根据本文所涉及的测量和计算方法，我们在多种复杂井下条件下，如对中、偏心、倾斜、屈曲、旋转、公转等，对随钻测井仪工具在井筒中所处位置附近的钻柱姿态进行了模拟。模拟和现场测试结果证明，随钻成像传感器与井壁之间的距离受井下姿态和公转的影响很大。基于上述测量的多传感器布局测量方案和数据处理，可以将井下专门研究的钻铤运动和偏心度矩阵从仅定性估计推进到实时测量和定量计算。上述测量和数据处理方法可以准确测量和识别随钻测井传感器所在钻柱的局部工作姿态，并定量给出随钻测井传感器环境校正所需的从测量点到井壁的偏心距矩阵。
