The bit-rock interaction considerably affects the dynamics of a drill string. One critical condition is the stick-slip oscillations, where torsional vibrations are high; the bit angular speed varies from zero to about two times (or more) the top drive nominal angular speed. In addition, uncertainties should be taken into account when calibrating (identifying) the bit-rock interaction parameters. This paper proposes a procedure to estimate the parameters of four bit-rock interaction models, one of which is new, and at the same time select the most suitable model, given the available field data. The approximate Bayesian computation (ABC) is used for this purpose. An approximate posterior probability density function is obtained for the parameters of each model, which allows uncertainty to be analyzed. Furthermore, the impact of the uncertainties of the selected models on the torsional stability map (varying the nominal top drive angular speed and the weight on bit) of the system is evaluated.
翻译:Bit-rock 互动关系在很大程度上影响到钻头字符串的动态。 一个关键条件就是刺滑振动, 其振动的振动非常高; 位角速度从零到大约是顶驱动器表面角速度的两次( 两次或两次以上) 。 此外, 在校准( 识别) Bit-rock 互动参数时, 应考虑到不确定性。 本文建议了一种程序, 来估计四个比特岩石互动模型的参数, 其中一种是新的, 同时选择最合适的模型, 并参考可用的字段数据。 为此使用了近似 Bayesian 的计算( ABC ) 。 每个模型的参数都获得了近似远地点概率密度函数, 从而可以分析不确定性。 此外, 将评估选定模型对 torsisonal 稳定性 地图( 标称顶驱动器角速度和位数重量) 的不确定性对系统图的影响 。