径向井钻杆截面变形模型及实验分析

径向水平井技术在国内外已研究多年。但其钻杆的弯曲状态、应力应变分布始终未见研究报道。现文运用刚塑性理论，对有限弯曲状态下的钻杆弯曲进行了建模，得出其中性层始终位于钻杆拉伸侧的结论。且随着钻杆上所受阻力的增加，中性层偏离越大；采用塑性增量理论，建立了钻杆截面变形模型，应用所建立的模型对实验结果进行了分析。从而确定了钻杆与滑道的间隙是决定钻进成败的关键。对比分析发现钻杆上的阻力，有相当一部分来自造斜器对钻杆的方向性挤压。这为改进造斜器的设计、增加钻进进尺指出了方向。

The modeling of the URRS drill pipe deformation and analyzing of the experiments

s:The ultra short radius radial system has been studied for many years in and out of the country. But, the research on drill pipe bending and the distribution of stress strain on drill pipe cross section have not been reported up to now. In this paper, the stress strain of drill pipe bending is modeled under the limit bending condition with rigid plasticity theory. It is concluded that the centurial layer during bending always stays at the stretched side. The more resistance loaded on the drill pipe, the more offset of the centurial layer. The drill pipe cross section is modeled under the plasticity increment theory. The experiment results are analyzed by using this model. One conclusion is that the clearance between drill pipe and slide way of whipstock is the key factor for drilling success. Contrasted the cross section dimension calculated with the measured, it is discovered that much resistance on drill pipe is coming from the directional extruding between drill pipe and the rollers of whipstock. It shows how to improve the design of whipstock and how to elongate the horizontal depth of drilling.