中文摘要：

建立空间圆弧轨迹的井斜方程，得到空间圆弧轨迹所在斜平面姿态、空间圆弧轨迹井斜角极值等求解方法，揭示空间圆弧轨迹的井斜演化规律及控制模式。可分别由正演模型和反演模型计算出空间圆弧轨迹上任一点的井斜角和方位角、斜平面姿态的倾斜角和倾斜方位角以及轨迹井斜角极值点参数，正演模型和反演模型的计算结果完全相同。空间圆弧轨迹或其趋势线存在井斜角极值点，极小和极大井斜角点的井眼轨迹切线分别指向所在斜平面的下倾和上倾方向，两个极值点的弯曲角和方位角均相差180°。斜平面姿态参数、井斜角极值点参数与井段始点的井斜角和工具面角有关，与井段长度无关。对于空间圆弧轨迹，斜面倾角模式存在二义性，应使用工具面角或定向方位角控制模式。图3表4参20

英文摘要：

The well deviation equation of circular-arc trajectory in space was established, the solution methods to determine the posture of the inclined plane that the circular-arc trajectory lies on and the extreme value of inclination angle of the circular-arc trajectory were presented, and the evolution pattern and control mode of well deviation for circular-arc trajectories in space was revealed. Some parameters can be calculated by the forward model and inverse model respectively, including the inclination angle and azimuth angle at any point along a circular-arc trajectory, the inclined angle and inclined azimuth angle of the inclined plane that the circular-arc trajectory lies on and the various parameters at the point with extreme inclination angle, and the calculated results from the forward model are the same as those from the inverse model. There are two points with extreme inclination angles along a circular-arc trajectory or its trendline, and the tangent lines of wellbore trajectory at the points with minimum and maximum inclination angles point to downdip and updip directions of the inclined plane respectively, the bending angle and azimuth angle differences between the two points are both 180°. The posture of inclined plane and parameters at extreme inclination points relate to the inclination angle and tool face angle at the beginning point of well interval, but have nothing to do with the interval length. The inclined angle mode for controlling a circular-arc trajectory is ambiguous, so the tool-face angle or directional azimuth angle modes should be used.