PDC切削齿切削深度对PDC钻头黏滑振动影响动态实验

Dynamic experimental on the influence of cutting depth of PDC cutter on stick-slip oscillation of PDC bit

通过室内动态破岩实验,研究切削齿切削深度及岩石可钻性对PDC钻头黏滑振动的影响。选取了红砂岩、黄砂岩、白砂岩和花岗岩4种不同岩性、400 mm×400 mm×400 mm的天然岩石作为实验岩样,通过改变钻压,分析切削齿切削深度、岩石可钻性与钻头黏滑振动的关系。选取扭矩和转速波动作为黏滑振动特征参数来描述PDC钻头黏滑振动现象,对其进行无因次化处理,定义为黏滑严重度,并分别建立了PDC钻头黏滑严重度、扭矩振幅,与平均每转切削深度和岩石可钻性的二元非线性关系模型。实验结果表明:实验室条件下扭矩黏滑严重度差异性更加明显;实验的5种钻压下,扭矩黏滑严重度均随岩样可钻性级值的增加而显著增加;PDC钻头每转切削深度增加,扭矩黏滑严重度显著增加。

The influences of cutter cutting depth and rock drillability on the stick-slip oscillation of PDC bit were researched by means of laboratory dynamic rock breaking experiment.400 mm×400 mm×400 mm natural red sandstone,yellow sandstone,white sandstone and granite were selected as experimental samples and the relationships of cutter cutting depth and rock drillability vs.stick-slip oscillation of PDC bit were analyzed by changing the weight on bit(WOB).Torque and rate of penetration(ROP)fluctuation were taken as the characteristic parameters of stick-slip oscillation to describe the stick-slip oscillation phenomenon of PDC bit,which were treated to be dimensionless and defined as the stick-slip severity.In addition,the binary nonlinear relationship model of stick-slip oscillation and torque amplitude of PDC bit vs.average cutting depth per revolution and rock drillability was established.It is experimentally indicated that the stick-slip severity of torque is more obvious under the experimental conditions.Under the five experimental WOB,the stick-slip severity of torque increases greatly with the increase of rock drillability grade value.What’s more,the stick-slip severity of torque increases greatly as the cutting depth per revolution of PDC bit increases.