Anti-collision analysis has been becoming even more important in the past few years with the increasing amount of wells drilled in highly congested fields. The separation factor (SF) is a critical safety parameter to avoid wellbore collisions, where the pedal curve method (PCM) is the commonly used way for the SF calculation. However, such method may be conservative in many situations and possibly triggers an unnecessary early stop drilling due to its conservation. In this study, our work aims to evaluate and compare the different types of the SF models. In addition, an alternative and supplement method of the PCM, called as elliptic cylinder of uncertainty (ECoU) method, is proposed. The radius of the ECoU considers the distance of the intersecting points of the center-to-center line and the cylinder surfaces of both reference and offset wells. By introducing the cylinder surfaces into the SF calculation, it could extend the collision avoidance along the whole well path to reduce multiple-points collision possibility. The findings in the study help us for better understanding of the SF analysis and also show that using the ECoU indication has a great potential in fields applications as a viable method to keep the drilling operations’ safety.

随着在高度拥挤的油田中钻井数量的增加，防撞分析在过去几年变得更加重要。分离系数（SF）是避免井筒碰撞的关键安全参数，其中踏板曲线法（PCM）是SF计算的常用方法。然而，这种方法在许多情况下可能是保守的，并且可能由于其保守性而触发不必要的提前停止钻井。在这项研究中，我们的工作旨在评估和比较不同类型的 SF 模型。此外，还提出了一种 PCM 的替代和补充方法，称为不确定性椭圆柱体 (ECOU) 方法。ECoU 的半径考虑了中心到中心线的交点与参考井和偏置井的圆柱面的距离。通过在SF计算中引入圆柱面，可以扩展整个井径的防撞范围，减少多点碰撞的可能性。研究结果有助于我们更好地理解 SF 分析，还表明使用 ECoU 指示作为保持钻井作业安全的可行方法在现场应用中具有巨大潜力。