二维井眼轨迹摩阻扭矩的影响因素分析

INFLUENTIAL FACTOR ANALYSIS OF 2-D WELL TRAJECTORY FRICTIONAL TORQUE

结合典型案例,应用二维轨迹摩阻扭矩算法分析了井身剖面、造斜段造斜率、方位突变等因素对摩阻扭矩的影响,建立适合水平位移小于1 400 m定向井的"直-增-稳-微降"三段制剖面几何模型及其约束方程,提出了降低摩阻扭矩的井眼轨迹控制要点。研究认为,造斜段造斜率过高会导致摩阻扭矩过大;降斜段降斜率增大、降斜段位置提前,均会造成后期钻进扭矩急剧上升;上部井段方位突变形成"拐点"会造成钻进摩阻扭矩过大;采用"直-增-稳-微降"剖面,控制增斜段增斜率≤2.5°/30 m、降斜段降斜率≤1.5°/30 m、上部井段无"拐点",摩阻扭矩可控制在安全作业范围。

A typical case was used to analyze the influence of the well profile,build-up rate,and the direction mutation on the well trajectory friction torque.The geometric model and constraint equation of the three section profile(that is 'straight –increase-steady-slowly drop ' profile) were established,which was suitable for directional well of the horizontal displacement less than 1400 m.The methods on well trajectory control of reducing friction torque were put forward.The research showed that when the build-up rate was too high,the friction torque would become large,when the drop-off rate increased or the drop-off position advanced,the drilling torque would rise sharply.The mutation of upper wellbore azimuth that formed the inflection point would cause drilling friction torque increase.When the ' straight – increase-steady-slowly drop' profile was adopted,the buildup rate was less than or equal to 2.5 degrees per30 m,and the drop-off rate was less than or equal to 1.5 degreesper 30 m,and the inflection point wasn't caused in the upper wellbore,the frictional torque could be controlled in the safe operation range.