三维定向井随钻监测的曲面投影方法

井眼轨道的投影图是监测实钻轨迹沿设计轨道行进情况的重要方法,但现有的平面投影方法对于三维定向井和水平井存在较大的误差,甚至导致失真和错误的分析结果。过设计轨道上诸点的铅垂线构成一个铅垂柱面,将实钻轨迹投影到该设计轨道所在的铅垂曲面上,能够科学有效地分析和评价实钻轨迹与设计轨道的符合程度。阐述了井眼轨道曲面投影的原理,建立了曲面投影视平移和水平偏距的概念和计算方法,从而可真实地反映实钻轨迹沿设计轨道在水平方向上的进程以及实钻轨迹与设计轨道的横向偏离程度。通过简单的数学模型,分析了平面投影产生误差的原因及误差估算方法。最后,用计算实例验证了曲面投影方法的科学性和可靠性。

A technique projecting drilled trajectory on path-plan curved surface for monitoring 3D directional wells while drilling

Projection of well path is an important approach to monitoring real drilling trajectory along designed path. However, the plane projection technique available now may lead to bigger error or irreal results as to 3D directional wells and horizontal wells. The vertical line across all points of designed path constitutes a vertical plane. The coincidence of real drilled trajectory with designed path could be analyzed and evaluated scientifically by projecting real drilled trajectory on the path-plan curved surface. This paper elaborates the principle of projecting well path on curved surface, proposes the definition and calculating method of vertical section and horizontal departure. So the real drilled trajectory horizontally along designed path and the lateral runout of real drilled trajectory and designed path could be reflected truly. With simple mathematical models, the cause and calculating method of error resulting from plane projection is analyzed. Finally, calculating examples are used to verify that the path-plan curved surface projection is scientific and reliable.