摘要
RDM钻井技术以同心双壁钻杆为基础,钻井液从双壁钻杆环空泵入井内,并从内部钻杆携带岩屑返回地面,从而实现钻井液闭环循环。该钻井技术中双壁钻杆环空流道中有支撑双壁钻杆内管的定位块,定位块对钻井液流动产生巨大影响。通过Fluent软件模拟钻井液在双壁钻杆环空内的流动规律,发现定位块处压力降低后逐渐增大,流速增加后迅速降低,定位块处出现4个轴对称最低流速区、最高流速区、最低压力区和最高压力区,固相颗粒浓度在壁面处最高。分析表明,双壁钻杆流道的过流面积小,而且由于定位块的存在,循环压耗较常规钻井大很多,故不宜采用大排量进行钻进。这为建立井底压力计算模型、优化定位块结构和优选钻井水力参数等提供了科学依据,对RDM钻井技术的发展具有积极作用。
The RDM drilling technology takes as the basis the concentric double-wall drillpipe,and drilling fluid is pumped into the well from the double-wall drillpipe annulus and returns by carrying cuttings from the inner drillpipe,thus achieving the closed-loop circulation of drilling fluid.In the drilling technology there is the locating block which supports the double-wall drillpipe's inner tube in the drillpipe annular channel and the block has great effect on the flow of drilling fluid.The flow law of drilling fluid in the double-wall drillpipe annulus was simulated through the Fluent software,finding out that the pressure decreased and then gradually increased and the flowrate increased and then decreased rapidly at the block where there appeared the minimum flowrate zone,maximum flowrate zone,minimum pressure zone and maximum pressure zone of axial symmetry and that the concentration of solid particles on the wall surface reached the maximum.The analysis showed that the open area of the double-wall drillpipe channel was small,and its circulating pressure loss was much greater than that in conventional drilling due to the existence of the locating block,therefore the large drill fluid discharge should not be adopted in drilling.
出处
《石油机械》
北大核心
2011年第5期20-22,33,共4页
China Petroleum Machinery
关键词
RDM
双壁钻杆
FLUENT
数值模拟
流场分布
RDM,double-wall drillpipe,Fluent,numerical simulation,flow field distribution
