水平井射流磨钻头粉碎钻屑与提高钻速的机理研究

Horizontal drilling has been considered as an ideal technique for developing unconventional oil & gas reservoirs. However, due to the low cuttings carrying capacity of horizontal drilling, cuttings bed easily forms, which may lead to the accidents such as wellbore plugging and pipe sticking. Moreover, the mechanical energy provided by the surface to drive the bit has a great transmission loss in horizontal drilling, it always results in low rate of penetration (ROP) and high drilling cost. Recently, the applicant introduced the jet comminution technique into the drilling industry, and developed a new type of bit called jet mill bit (JMB) which provides a promising solution to the problems by depressuring and comminuting cuttings into dust-like scale right after the cuttings are generated in the bottom hole. The key issues of the JBM are the hydrodynamic jet comminution characteristics based on the fluid-particle two-phase jet in JMB, jet comminution mechanism and depressuring mechanism under the submerged condition. Focusing on these issues, following works should be done: research on the fluid-particle two-phase mixing mechanism and the cuttings accelerating characteristics, experimental research on the mechanical behavior of the cuttings regrinding in JMB， research on the downhole flow field characteristics of JMB and experimental research on the JMB’s depressuring performance. This work will provide solid theoretical fundamentals to promote the optimal design and execution of the JMB.

水平井目前被广泛用于开发非常规油气资源，然而水平井钻进时携岩困难、托压严重、机械钻速慢、钻井成本高。我们创造性的提出采用粉碎钻屑的方法提高携岩效率，并将射流磨粉碎技术首次引入钻井行业中，研发了一种水平井射流磨钻头，它既能降低井底压差实现欠平衡提高机械钻速，又能粉碎钻屑尽可能实现钻屑悬浮运移状态，可望有效避免水平井钻井过程中钻屑床的形成，为水平井的安全高效钻井作业提供技术支撑。其关键科学问题是射流磨钻头内部液固两相射流水动力学碎屑特性、井底淹没条件下射流粉碎钻屑机理及射流磨钻头降低井底压差机理。针对这一关键科学问题，本项目拟开展射流磨钻头粉碎钻屑过程中液固两相混合机理及钻屑加速特性研究，射流磨钻头二次碎屑力学行为的实验研究，射流磨钻头井底流场特性及降低井底压差性能的实验研究。研究成果可望揭示水平井射流磨钻头的水动力学碎屑特性和参数影响规律，为水平井射流磨钻头的优化设计与应用提供科学理论依据。

水平井目前被广泛用于开发非常规油气资源，然而水平井钻进时携岩困难、托压严重、机械钻速慢、钻井成本高。我们创造性的提出采用粉碎钻屑的方法提高携岩效率，并将射流磨粉碎技术首次引入钻井行业中，研发了一种水平井射流磨钻头。本课题通过理论推导、数值模拟、实验研究相结合的方式展开射流磨钻头粉碎钻屑与提高钻速的机理研究。首先，建立了射流磨钻头内部固液两相流动数值模型，对射流磨钻头内部流道的流场进行仿真分析，揭示了钻屑颗粒和流体的两相混合机理以及钻屑随高速射流的加速特性。其次，结合粉碎能耗理论和冲击动力学理论对淹没条件下钻屑冲击破碎过程进行力学行为分析，推导了岩屑在混合加速管中随钻井液加速运动的理论方程。研制了射流磨钻头钻屑射流粉碎实验装置，开展室内实验，揭示了没条件下钻屑的射流粉碎机理。再次，建立了井底淹没条件下射流磨钻头的井底流场数值模型，对射流磨钻头的井底流场特性进行研究，揭示井底淹没条件下射流磨钻头降低井底压差和压持效应的机理。开展了射流磨钻头降压性能实验，对比验证数值仿真计算结果的可靠性。研究成果可望揭示水平井射流磨钻头的水动力学碎屑特性和参数影响规律，为水平井射流磨钻头的优化设计与应用提供科学理论依据。研究成果在Renewable & Sustainable Energy Reviews、Petroleum Science、Journal of Energy Resources Technology等国际著名期刊及会议上发表论文11篇，其中SCI检索7篇，EI检索3篇，中文核心1篇；已授权国家发明专利3件、实用新型专利1件，申请国家发明专利2件；获省部级二等奖1项；参加国内外学术会议4次；培养博士研究生1名，硕士研究生2名。