钻探实践表明,降低井底压差,减小岩屑的压持效应,并尽量实现井底的欠平衡条件,可以显著提高机械钻速.在介绍射流降压技术原理的基础上,综述了环空射流泵、射流降压短节和射流泵钻头等射流泵降压工具的结构特点、降压效果和研究应用现状,并分析了影响各种降压工具降压性能的关键因素.环空射流泵采用单独的动力液驱动射流泵动作,井筒环空压力可降低当量钻井液密度0.16～0.52 kg/L；射流降压短节降压范围有限,当射流泵出口距离井底2m时,对井底环空几乎没有降压效果；井壁间隙是射流泵钻头降压能力的关键,当井壁间隙为1 mm时,射流泵钻头可使井底压力降低1.86 MPa；当井壁间隙增大到3 mm以上时,射流泵钻头几乎没有降压效果.研究结果为射流泵降压工具的研发提供了理论指导.%According to the experience of oil/gas drilling,ROP in well drilling can be improved signifi-cantly when the bottom hole pressure drops,chip hold down effect of cuttings was reduced,and under bal-anced condition was achieved. This paper summarized the structure features,depressurization capacities,and the current status of researching and developping jet pump,jet pump joint and jet pump bit based on the de-pressure principle of jet pump. The key factors that affect the depressurization capacity were analyzed. An-nulus jet pump is actuated by a jet pump. It can reduce the equivalent circulation density about 0. 16-0. 52 kg/L. The depressure ability of the jet pump joint is lower than that of jet pump, and there is almost no pressure drop when the outlet of the jet pump is two meters off the bottom hole two meters. The clearance between bit and borehole wall is critical to the depressure ability of the jet pump bit. When the bit clearance is 1 mm,about 1. 86 MPa is reduced;however,when the bit clearance is increased to more than 3 mm, the pressure is almost unchangeable. The results can provide the theoretical guidance for the development of the jet pump depressure tools.
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