滑动钻进造斜率预测与分析

Prediction and analysis of build-up rate during sliding drilling

滑动钻进工况下造斜率的准确预测是钻井工程面临的难点问题。首先利用加权余量法,建立了导向钻具组合的三维力学模型,得到了滑动钻进过程下钻头机械载荷及导向钻具组合的摩阻分布;其次考虑滑动钻进过程中工具的造斜特性,建立了零侧向钻速准则下的滑动钻进造斜率预测模型及折算系数反演方法;最后利用一口页岩气水平井钻井数据,反演计算了该井造斜率折算系数,验证了滑动钻进造斜率预测模型的精度,并分析了钻井参数、轨迹参数、钻头切削特性、工具结构等对工具造斜率和摩阻的影响规律。研究结果表明:滑动导向模式下,通过适当增加工具结构弯角、降低钻压、提高钻头侧向切削能力等,有利于发挥工具的造斜性能,提高滑动钻进效率,为导向钻井参数优化、工具结构优化设计及井眼轨迹控制等提供重要依据。

The drilling engineering is facing difficulties in accurately predicting the build-up rate during the sliding drilling operation.First,this research developed the three-dimensional mechanical model of the steering bottomhole assembly(BHA),based on the weighted residual method,and calculated the mechanical load of the bit and friction distribution in the steering BHA during sliding.Moreover,given the build-up characteristics of the tool during sliding,the sliding build-up rate prediction model with a zero side penetration rate and the inversion method of the conversion coefficient were developed.At last,the build-up rate conversion coefficient of a shale gas horizontal well was inverted from its drilling data and this application confirms the precision of the proposed sliding build-up rate prediction model.Besides,the effects of drilling parameters,trajectory parameters,cutting characteristics of the bit,and tool structure on the build-up rate and friction of the tool are investigated.It is shown that during the sliding steering,it is in favor of improving the build-up performance of the tool and the sliding drilling efficiency to properly increase the structural bend angle of the tool,lower the weight on bit,and enhance the side cutting performance of the bit.The findings of this research provide vital references for optimizing the steering drilling parameters,tool structure design,and well trajectory control.