Journal of Petroleum Science and Engineering ( IF 5.168 ) Pub Date : 2020-03-04 , DOI: 10.1016/j.petrol.2020.107136 Alexander Busch , Stein Tore Johansen
Drill pipe rotation is considered a relevant factor for cuttings transport and hole cleaning. However, in the term “rotation” is often used as a moniker for the combination of plain drill pipe rotation around its own axis and more complex lateral motion, as many laboratory setups feature an unconstrained drill string. Lateral motion is generally considered to benefit the transports of cuttings due to increased bed agitation. By means of Computational Fluid Dynamics, we have investigated the effect of synchronous and asynchronous whirling drill string motion on the cuttings bed and cuttings transport for water and a more viscous, shear-thinning fluid using the Two Fluid Model in conjunction with the Kinetic Theory Of Granular Flows and closures from soil mechanics to rheologically describe granular matter. The dynamic mesh capability of ANSYS Fluent R17.2 is exploited to account for the orbital motion of the drill string. In addition, three base cases (negative eccentric, concentric, and positive eccentric) are investigated for comparison. Whirling motion helps tremendously to disperse the solids into the main flow region and hence improves the quality of cuttings transport and hole cleaning, with synchronous whirl by far outperforming asynchronous whirl due to the cumulative tangential and radial velocities. The effect is much more prominent for water than for the more viscous, shear-thinning fluid because the latter already shows a comparatively good cuttings transport performance. Moreover, in case of the more viscous, shear-thinning fluid, the positive eccentric annulus provides an even better cuttings transport capability, if comparison is made on equivalent pressure gradients. Because of the higher viscosity level, the whirling motion reduces the axial throughput, which despite the increased bed agitation results in worse performance compared to the positive eccentric case.
中文翻译:
钻屑运输:钻杆旋转和横向运动对钻屑床的影响
钻杆旋转被认为是钻屑运输和孔清洁的相关因素。但是,术语“旋转”通常用作平面钻杆绕其自身轴线旋转和更复杂的横向运动的组合的称呼,因为许多实验室设置都具有不受约束的钻柱。由于床层搅动的增加,通常认为横向运动有利于岩屑的运输。通过计算流体动力学,我们结合两种流体模型,研究了同步和异步旋转涡流钻柱运动对水和更粘稠,剪切稀化流体的钻屑床层和屑屑输送的影响。从土壤力学到流变学的颗粒流和封闭物描述了颗粒物。利用ANSYS Fluent R17.2的动态网格功能来解释钻柱的轨道运动。此外,还研究了三种基本情况(负偏心,同心和正偏心)进行比较。旋转运动极大地帮助将固体分散到主流区域,因此提高了钻屑运输和孔清洁的质量,由于累积切线和径向速度,同步旋转远远优于异步旋转。对于水来说,这种效果比对粘性更薄的剪切稀化流体更为显着,因为后者已经显示出了相对较好的岩屑运输性能。此外,如果使用的是粘性更强,剪切稀疏的流体,则正偏心环将提供更好的切屑输送能力,如果在等效压力梯度上进行比较。由于较高的粘度水平,回旋运动降低了轴向通过量,尽管增加了床的搅动,但与正偏心情况相比,其性能仍然较差。