井眼轨迹精准定位技术

Precise Positioning Technique for Wellbore Trajectories

现行井眼轨迹定位方法采用网格北作为指北基准,在靶点和井口范围内将参考椭球面近似为水平面来定位靶点相对于井口的空间位置,在实钻井眼轨迹计算中没有考虑各测点处磁偏角随时间和空间的变化,存在固有缺陷和较大误差。为此,采用真北作为指北基准,基于地球椭球及其解算原理来定位靶点与井口间的相对位置,利用国际地磁参考场随时随地求取磁偏角,考虑磁偏角的时空变化并用迭代法计算实钻井眼轨迹。井眼轨迹精准定位技术从根本上解决了现行定位方法存在的问题,保证了井眼轨道设计与轨迹监测的精确性和可靠性。

To determine the relative spatial position of the target to the wellhead,grid north is currently used as the benchmark for North,which positions the ellipsoid into the horizontal plane as the approximate reference coordinate.Because it does not consider the change of magnetic declination with the change of time and space at the measuring points,the conventional calculation of drilled wellbore trajectory exhibits inherent defects and significant errors.In order to solve the problem,True North can be used as the reference North to determine the relative position between the target and wellhead in terms of earth ellipsoid and its calculation principle.It can also be used to determine the magnetic declinations based on international geomagnetism reference field,which considers the changes of magnetic declinations with time and space to calculate the drilled wellbore trajectory by an iterative method.The innovative method can effectively eliminate drawbacks of existing positioning techniques and ensure accuracy and reliability in design and monitoring of wellbore trajectories.