悬链线轨道设计方法研究

悬链线轨道可以降低钻柱摩阻，改善钻柱的受力状况，有利于提高机械钻速和固井质量，在大位移井中具有显著的优越性。为此，系统地阐述了悬链线轨道的数学模型，并改进了无因次模型，使其更为简洁。分析了悬链线剖面的特征参数和设计条件，提出了新的悬链线剖面设计方法。新设计方法不需要进行迭代计算，可直接求解出井身剖面的待求参数，使悬链线轨道的设计过程大为简化。研究表明，悬链线剖面设计的实质就是确定悬链线井段的形状和位置；悬链线的特征参数决定了其形状，而悬链线井段的起始井斜角或稳斜井段的段长等参数决定了悬链线井段在井身剖面中的位置。最后，给出了悬链线剖面的设计与计算实例。

CATENARY PROFILE DESIGN METHOD STUDY

The catenary profile can reduce the drill string drag, improve the load distribution along the string, increase ROP, and improve cementing quality, exhibiting great advantages especially in extended reach drilling (ERD) wells. This study described the mathematic model of the catenary profile, and improved the dimensionless model in a simplified way. At the same time it analyzed the characteristic parameters and designing conditions of the catenary profile, based on which a new design method is put forward. By this new method, the profile parameters could be directly determined without any iterative computation, and the design was simplified to a high degree. The study showed the catenary profile design was essential to decide the shape and location of the catenary section. While the characteristic parameters decided its shape, the initial inclination and the length of the holding section would decide the location of the catenary section along the whole well profile. This study also gave out some examples for design and calculation of the catenary profile.