基于自进式多孔旋转射流提高径向水平钻井破岩效率与延伸能力研究

It is the key to improve the rock-breaking efficiency and increase the extension capacity within limited discharge rate for the new radial horizontal drilling technology. The performance of jet bit is the primary problem of the pivotal technology. The self-propelled swirling multi-jet bit was developed and its properties were analyzed on the basis of swirling jet and multiple jets. Furthermore, rock breaking experiments of optimizing self-propelled swirling multi-jet bit and its structural parameters optimization experiments were designed under confining pressure condition. According to the rock breaking rules of self-propelled swirling single jet bit, self-propelled combined swirling and round single jet bit, self-propelled swirling multi-jet bit and self-propelled combined swirling and round multi-jet bit changing with time, jet pressure and standoff distance, the jet bit with high rock breaking efficiency was optimized. Based on the theories of fluid dynamics, computational fluid dynamics and jet dynamics, etc., the mathematical model of the self-propelled force for the new jet bit was developed. The model was verified through self-propelled force testing experiment. And the ultimate extension length calculation model of radial horizontal wellbore was established according to the mathematical model of the self-propelled force and the kinematic equation of the jet bit and high pressure hose system. Consequently, the related parameters can be optimized to increase the extension length of the radial horizontal wellbore. The study has important scientific significance, which can provide theoretical guidance for radial horizontal drilling technology.

利用有限的排量实现高效的破岩效率并尽可能增大径向水平井眼的延伸能力是实施新型径向水平井技术的关键，射流钻头的性能是该关键技术要解决的首要问题。本项目拟在旋转射流及多孔射流基础上，设计研制出自进式多孔旋转射流钻头，并分析其性能；在围压条件下，设计用于优选自进式多孔旋转射流钻头的破岩实验及其结构参数优化实验，根据自进式单孔旋转射流钻头、自进式单孔直旋混合射流钻头、自进式多孔旋转射流钻头以及自进式多孔直旋混合射流钻头随时间、射流压力和喷距的破岩钻孔规律，进行高效破岩射流钻头优选；基于流体力学、计算流体力学及射流动力学等理论，建立新型射流钻头的自进力数学模型，并通过自进力测试实验对所建模型加以验证；基于自进力数学模型及射流钻头与高压软管系统运动方程，建立径向水平井眼极限延伸长度的计算模型，以优化相关参数来提高径向水平井眼延伸长度。本研究具有较大的科学意义，可为径向水平钻井技术的发展提供理论指导。

如何利用有限的排量实现高效的破岩效率并尽可能增大径向水平井眼的延伸能力是新型径向水平井技术的实施关键。因此开展径向水平井射流钻头优化设计及其流场特性、高效破岩射流钻头的优选，自进式水射流钻头自进机理和延伸能力等方面的研究，对发展和完善径向水平井技术具有重要理论和实际意义。.在多孔射流钻头的基础上，设计研制了自进式旋转射流钻头。基于流体力学和机械设计理论，优化了射流钻头本体和叶轮的结构参数，通过数值模拟方法研究了自进式旋转射流钻头的流场特性。根据数值模拟结果，可将自进式旋转射流钻头全域流场分为井底漫流区、正向射流区、反向射流区、低速流区等几个区域。自进式旋转射流钻头的冲击范围较单孔射流钻头和多孔射流钻头优势明显。.针对水射流破岩和自进式旋转射流钻头结构的特点，设计了用于优选自进式旋转射流钻头的破岩实验及其结构参数优化实验，根据自进式单孔旋转射流钻头、自进式单孔直旋混合射流钻头、自进式多孔旋转射流钻头以及自进式多孔直旋混合射流钻头随时间、射流压力和喷距的破岩钻孔规律，进行高效破岩射流钻头优选。通过实验方法优化了高效破岩射流钻头的结构参数，得到了一种高效破岩的射流钻头。.基于流体力学、计算流体力学及射流动力学等理论，对射流钻头自进力的理论进行了分析，并通过自进力测试实验对所建模型进行了验证。建立了径向水平井眼极限延伸长度的计算模型，分析了摩擦系数、流量、反向喷嘴数目和孔眼扩散角等参数对径向水平井眼极限延伸长度的影响。结果表明：改变系统的流量、反向喷嘴数目和反向喷嘴直径可以使径向水平井的极限延伸长度发生明显改变；改变孔眼扩散角，只能在一定范围内改变径向水平井的极限延伸长度。提出了推进式径向水平井钻进方法，通过分析高压软管在井眼中的屈曲状态，建立相应的延伸极限计算模型，为提高径向水平井的延伸能力提供新的思路。