定向井滑动钻进送钻原理与技术

定向井和水平井钻进经常采用滑动钻进方式。地面间歇向井内送入钻杆是如何转化成井下钻柱对钻头的推进的？如何减小钻柱与井壁的滑动摩擦力给钻压带来的误差？现有的滑动钻进送钻技术各有什么优缺点？这些都是业界关心的问题。为此，把钻具送到井底并加上钻压，暂停地面送钻操作的工况作为研究区间，分析了井底的钻柱弹性、水力振荡器和液力推进器3种送钻原理。阐述了带井下动力的钻具组合、带水力振荡器的钻具组合和带液力推进器的钻具组合的滑动送钻技术，给出了地面钻进参数与井底钻进参数的关系。进而比较了3种送钻技术的特点：带井下动力的钻具组合在井底是依靠钻柱的弹性推动钻头前进；带水力振荡器的钻具组合依靠其产生的水力振动来降低钻柱与井壁间的滑动摩擦力，改善钻压传递效率；带液力推进器的钻具组合在其工作钻压区间，依靠活塞推动钻头前进。结论认为，带液力推进器的钻具组合滑动送钻技术最优，钻压可调、平稳，液力推进器可串联使用，钻进时可以活动上部钻柱。

Bit feed principles and technologies in slide drilling directional wells

Slide drilling is frequently applied to directional and horizontal wells. How does the action of intermittently running drill pipes transform into the bit advancement via downhole drill string? How to reduce the error caused by sliding friction between the drill string and wellbore? What are the merits and demerits of the existing slide drilling bit feed technology? In order to answer these questions, an analysis was made under the following working condition: running into the bottomhole assembly (BHA), applying weight on bit (WOB), and suspending the ground bit feed, under which three bit feed principles were analyzed respectively:the downhole drill string elasticity, hydraulic oscillator, and hydraulic thruster. On this basis, the slide drilling technologies of BHA were introduced respectively with downhole motor, hydraulic oscillator and hydraulic thruster, and the relationship was explained between ground drilling and bottomhole drilling. Furthermore, these three bit feed technologies were compared, and the following characteristics were discovered: BHA with downhole motor feeds the bit by utilizing the drill string elasticity; BHA with hydraulic oscillator reduces the sliding friction between the drill string and wellbore by creating hydraulic vibration, thus improving the transfer efficiency of WOB; BHA with hydraulic thruster feeds the bit with piston, and the WOB is within its working range. Based on the analysis, the optimal slide drilling technology is the combination of BHA and hydraulic thruster since it has adjustable and stable WOB, the hydraulic thruster can be used in series, and moreover, a short trip can be made to the upper drill string during drilling.