月牙形和偏心圆筒形内壁磨损套管应力分析

为了分析偏心圆筒形磨损套管和月牙形磨损套管的等效应力,以177.8 mm×12.65mm的P110钢级套管为例,建立了月牙形磨损套管和偏心圆筒形磨损套管的有限元模型,用有限元法分析了内、外压作用下不同磨损深度套管的偏心圆筒形模型和月牙形磨损模型的等效应力,同时还分析了不同直径钻杆磨损后月牙形磨损套管的等效应力。分析结果表明,受磨损套管内部应力的影响,在内、外压作用下月牙形磨损套管的等效应力大于偏心圆筒形磨损套管的等效应力;将月牙形磨损模型转化为偏心圆筒形模型来分析磨损套管的等效应力是危险的,相同磨损深度和载荷作用下月牙形磨损模型的等效应力更大;将月牙形磨损模型转化为偏心圆筒形模型来分析磨损套管的剩余强度值偏大。

Stress Analysis of the Crescent and Eccentric Cylinder-shaped Inner Wall Worn Casing

To analyze the equivalent stress of eccentric wear casing and crescent wear casing,the finite element model of crescent wear casing and eccentric wear casing was established with the 177.8 mm×12.65 mm P110 steel grade casing as an example.The finite element method was used to analyze the equivalent stress of eccentric cylinder model and crescent wear model of different wear depths under effects of internal and external pressures.Meanwhile,the equivalent stress of crescent wear casing after abrasion of drillpipe with different diameters was analyzed.The analysis shows that due to effects of internal stress of worn casing,the equivalent stress of crescent wear casing is greater than that of eccentric cylinder wear casing under the effect of internal and external pressures.It would be improper to make an analysis of the equivalent stress of worn casing by converting crescent wear model into eccentric cylinder model.The equivalent stress of crescent wear model is greater under the effect of the same wear depth and load.The residual strength value of worn casing is relatively large if the analysis is conducted by converting crescent wear into eccentric cylinder model.