The multistage stimulation technique and horizontal wells are increasingly being utilized to improve oil and gas recovery. However, the sticking that occurs due to large drag during the completion string with packers tripping into the horizontal section, resulting in an abandoned well and huge economic losses. Based on a classical drag model, this paper illustrates how local drags affect the overall stress of the completion string by a case study. Mechanical models are also presented for analyzing the local drag of packers in horizontal sections considering the effects of microsteps or slots, borehole curvatures, and caliper variation respectively. The results confirmed that the local contact force is affected by centralizers, and local drags can be magnified during their upward transmission process. It is revealed that the slopes of microsteps or slots affect more on local drag of packers than the effects of microsteps’s height and slots’ depth; Moreover, the local drag of the packer was found increases with the increase of the borehole curvature, but less affected by the caliper variation; As to the effect of cuttings on the local drag of packers, it is affected by cuttings size and cuttings amount and cannot be quantitatively analyzed. This research could be utilized as a theoretical reference for estimating the sticking risks of the completion string and conditioning the horizontal open hole.

中文翻译：

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水平井封隔器完井管柱局部阻力

多级增产技术和水平井越来越多地被用于提高油气采收率。然而，完井管柱由于大阻力，封隔器下钻至水平段而发生卡钻，造成一口废弃井和巨大的经济损失。本文基于经典阻力模型，通过案例研究说明局部阻力如何影响完井管柱的整体应力。还提供了机械模型，用于分析水平段封隔器的局部阻力，分别考虑微台阶或狭缝、钻孔曲率和卡尺变化的影响。结果证实，局部接触力受扶正器的影响，在向上传递过程中局部阻力会被放大。结果表明，微台阶或槽缝的坡度对封隔器局部阻力的影响大于微台阶高度和槽深的影响；此外，发现封隔器的局部阻力随着钻孔曲率的增加而增加，但受卡尺变化的影响较小；至于钻屑对封隔器局部阻力的影响，受钻屑大小和钻屑量的影响，无法定量分析。该研究可为完井管柱卡钻风险评估和水平裸眼调节提供理论参考。至于钻屑对封隔器局部阻力的影响，受钻屑大小和钻屑量的影响，无法定量分析。该研究可为完井管柱卡钻风险评估和水平裸眼调节提供理论参考。至于钻屑对封隔器局部阻力的影响，受钻屑大小和钻屑量的影响，无法定量分析。该研究可为完井管柱卡钻风险评估和水平裸眼调节提供理论参考。