延长油田丛式井网加密水平井直井段交碰风险量化分析

为经济有效开发低渗透、低丰度油藏，延长油田利用旧井场部署加密水平井进行调整开发，直井段丛式井网密集，交碰风险严峻。为准确地评价直井段交碰风险，从实钻数据出发分析了延长油田水平井直井段轨迹水平位移偏差，并采用数学统计的方法对加密井直井段交碰风险进行量化，结果表明，直井段实钻轨迹水平位移偏差在同一井深下符合正态分布，随井深的增加，其均值和方差逐渐增大，正态分布形态越来越扁平，井眼位置不确定性越来越大。杏4003平34井应用结果表明，基于概率统计与可信度计算的直井段交碰风险定量分析，可较准确地判断直井段井眼碰撞风险，为丛式井网加密水平井直井段轨迹设计提供了新的参考。

Quantitative analysis on collision risk of vertical hole section of infill horizontal well in cluster well pattern in Yanchang Oilfield

To develop low-permeability and low-abundance oil reservoirs economically and efficiently in Yanchang Oilfield, infill horizontal wells are arranged at the old well sites.Thus, the vertical hole sections in the cluster pattern are dense, so the collision risk is rigorous.To evaluate the collision risk of vertical hole sections accurately, the horizontal displacement deviation of vertical hole sections in horizontal wells in Yanchang Oilfield was analyzed based on actual drilling data.Then, the collision risk of vertical hole sections in infill wells was quantified by means of mathematical statistics.It is indicated that the horizontal displacement deviation of actual trajectory of vertical hole section in the same hole depth is in accordance with the normal distribution.And with the deepening of the hole, its mean and variance increase gradually, the shape of normal distribution becomes flatter and flatter, and the hole location become moreand more uncertain.This method was applied in horizontal well Xing 4003 Ping 34.It is shown that quantitative analysis on the collision risk of vertical hole section based on probability statistics and confidence calculation can discriminate the collision risk of vertical hole section more accurately, and provides the new reference for the trajectory design of vertical hole section of infill horizontal well in cluster pattern.