水平井裸眼分段压裂完井管柱下入屈曲磨损预测模型及规律

针对水平井裸眼分段压裂完井管柱下入屈曲磨损的问题,使用微元法确定管柱轴力及摩擦阻力,采用能量法计算管柱临界屈曲载荷,根据White和Dason的"磨损效率"模型,建立了全井段管柱定量摩擦磨损量预测模型。基于此,探究了压裂级数、分段间距、油管规格对管柱屈曲及磨损的影响规律。研究结果表明:1压裂级数的提高使管柱中和点上移,每提升10级压裂,中和点约上移13.5 m,而分段间距长度和油管规格提高使中和点下移;2管柱屈曲风险随压裂级数增大而增大,随油管规格和分段间距长度增加而减小,每提升1 m分段间距长度,管柱最大屈曲风险位置的安全系数约提高0.1;3压裂级数与分段间距对管柱全井段磨损量影响较小,而油管规格提高使得管柱全井段磨损深度减小,但磨损面更宽。

Prediction model and law of buckling wear of open hole staged featuring completion string in horizontal well

To solve the problem of buckling wear of open hole stagedfeaturing completion string in horizontal well, the axial force and frictional resistance of string was determined using the infinitesimal method, and the critical buckling load of string was calculated out using the energy method. Based on the wear efficiency model of White & Dason, a quantitative frictional wear prediction model was developed for the completion string. On this basis, the influence of fracture stage, segment spacing and pipe specification on the buckling and wear of string was investigated. The results show that:(1)the neutralization point of the string is shifted upward due to the upgrade of fracturing stages, and the neutralization point shifts upward by about 13.5 m for each 10-stagefracturing upgraded, while the neutralization point is shifted downward due to the increase of segment spacing length and the improvement of pipe specification; (2)the risk of string buckling increases with the upgrade of fracturing stages and decreases with the increase of segment spacing length and the improvement of pipe specification, and the safety factor of maximum buckling risk location increases about 0.1 for each 1 m of segment spacing length; (3)the influence of fracture stages and segment spacing on the wear amount of the whole pipe string is small, while the improvement of pipe specification decreases the wear depth of the whole pipe string, and widens the wear surface.