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钻头水马力、冲击力及喷射速度是优选喷射钻头水力参数的通用标准。本文提出了一个基于最大冲击压力理论的新的改进标准与技术,并介绍了一种定量评价钻头水力参数的方法。 冲击压力是钻井液分布在井底受冲击面上的动量变化。这种向下及向侧面作用的力力图克服岩屑的压持效应,排除钻头下面的岩屑。当钻头压降为泵压的45—80％时,产生最大冲击压力。而产生最大冲击压力所需钻头压降百分数取决于泥浆流动性能、喷嘴数目、喷嘴截面积及其长度。 以往的试验表明,采用加长或封堵喷嘴就可提高钻速。应用冲击压力概念可定量地说明,加长或封堵喷嘴钻头的水力参数要比普通喷嘴钻头的水力参数好。从冲击压力和压差对比中也可得出钻头水力参数与转速的关系。
Drill bit horsepower, impact and jet speed are preferred jet hydraulic parameters of the common standard. This paper presents a new improved standard and technique based on the maximum impact pressure theory and introduces a method for quantitative evaluation of bit hydraulic parameters. Impact pressure is the momentum distribution of the drilling fluid distributed on the impacted surface of the bottom hole. This downward and side-by-side force map overcomes the hold-down effect of cuttings and excludes cuttings beneath the drill bit. When the drill pressure drop is 45-80% of the pump pressure, the maximum impact pressure is generated. The percentage of bit pressure drop required to generate the maximum impact pressure depends on mud flow properties, number of nozzles, nozzle cross-sectional area and length. Previous tests have shown that the use of longer or blocked nozzles can increase the rate of drilling. The concept of impact pressure can be used to explain quantitatively that the hydraulic parameters of a longer or blocked nozzle bit are better than the hydraulic parameters of a common nozzle bit. From the impact pressure and pressure contrast can also be drawn drill bit hydraulic parameters and speed relationship.