﻿ 井眼轨迹精准定位技术

Precise Positioning Technique for Wellbore Trajectories
LIU Xiushan
Sinopec Research Institute of Petroleum Engineering, Beijing, 100101, China
Abstract: 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.
Key words: drilling theory     directional drilling     wellbore trajectory     precise positioning

1 地球椭球及坐标系统 1.1 地球椭球的几何形状

 图 1 地球椭球及坐标系统 Fig.1 Earth ellipsoid and coordinate systems

1.2 大地基准及高程

1.3 地球椭球定位及定向

1.4 坐标系统

2 地磁场及地磁参考场

 (1)

 (2)

3 设计井眼轨道定位

 (3)

 (4)

4 实钻井眼轨迹定位

 (5)
 (6)

 (7)
5 应用实例

 定位点 经度 纬度 大地高/m 井口 119°45′E 50°N 700.00 A靶点 119°45′11.3775″E 50°0′5.3279″N -1 597.99 B靶点 119°47′53.6754″E 50°0′53.3435″N -1 596.85

 定位点 X/m Y/m Z/m N/m E/m H/m 水平位移/m 平移方位角/(°) 井口 -2 038 613.23 3 566 833.38 4 863 325.27 0 0 0 0 A靶点 -2 038 014.36 3 565 329.08 4 861 670.69 164.58 226.53 2 298.00 280.00 54.00 B靶点 -2 040 254.76 3 562 738.95 4 862 624.76 1 648.86 3 456.90 2 298.00 3 830.00 64.50 注：X，Y和Z为地固空间直角坐标系下的坐标；北坐标、东坐标、垂深为井口坐标系下的坐标。

 D/m α/(°) φm/(°) 测量时刻 δ/(°) φT/(°) N/m E/m H/m 水平长度/m 水平位移/m 平移方位角/(°) 0 0 2016-02-07 -10.316 0 0 0 0 0 2 000.00 0 (60.00) 2016-03-26 -10.332 (49.660) 0 0 2 000.00 0 0 (49.66) 2 170.00 45.00 60.00 2016-05-15 -10.340 49.660 41.04 48.32 2 153.05 63.40 63.40 49.66 2 300.00 45.00 65.00 2016-08-08 -10.352 54.648 97.42 120.89 2 244.98 155.32 155.26 51.14 2 440.00 90.00 70.00 2016-10-01 -10.360 59.640 165.53 226.90 2 297.19 281.37 280.86 53.89 6 000.00 90.00 80.00 2016-12-19 -10.388 69.612 1 689.17 3 439.40 2 297.19 3 841.37 3 831.81 63.84 注：井深、井斜角和磁方位角为测量数据；磁偏角、真方位角、北坐标、东坐标、垂深、水平长度、水平位移、平移方位角为计算结果。磁(真)方位角括号内的数据为定向方位角，平移方位角括号内的数据类似于方位角。

6 结论

1) 由于地图投影存在变形、地球椭球面并非水平面、磁偏角随时空变化等原因，现行定位方法存在固有缺陷和较大误差。

2) 现行定位方法算得的靶点垂深偏小、水平位移偏大。基于地球椭球的靶点定位方法不涉及地图投影问题，能精准定位靶点相对于井口的空间位置。

3) 地磁场随时间和空间变化，井眼轨迹上各测点处的磁偏角不同，利用国际地磁参考场求得的磁偏角等数据能满足钻井工程的精度要求。对于水平位移大、施工周期长的定向井，应考虑各测点处磁偏角的变化来定位井眼轨迹。

4) 新定位方法能提高井眼轨道设计与井眼轨迹监测的精度及可靠性，值得推广应用。

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#### 文章信息

LIU Xiushan

Precise Positioning Technique for Wellbore Trajectories

Petroleum Drilling Techniques, 2017, 45(5): 8-12.
http://dx.doi.org/10.11911/syztjs.201705002