【摘要】 高压射流以其自身所具有的运动特性和动力特性,在各个领域得到广泛的应用,喷射钻井是高压射流技术在钻井工程中的重要应用。依据射流外边界上液流束冲击压力与围压力的平衡关系,重新给出了射流外边界的定义,通过分析建立了围压对射流截面的影响模型和围压下的射流冲击压力计算模型,通过实例计算分析,得出了围压对射流外边界形状的影响规律;在相同的射流作用下,围压增大,射流对作用面的冲击力会明显减小,在围压大于一定值后,围压对射流基本段内冲击力的影响大于对初始段内冲击力的影响;较大的钻井液密度,在一定程度上有助于减小围压对井底射流的影响等重要结论。这对认识深井高围压环境下的射流特征、补充和完善喷射钻井理论有重要意义。更多还原

【Abstract】 High-pressure jet is widely used in all aspects due to its kinetic and dynamic behaviors. Jet drilling is one of the important applications of high-pressure jet technology in drilling engineering. Based on the equilibrium between the impact pressure and the confining pressure of the liquid flow formed at the external boundary of the jet, the external boundary of the jet is redefined, a model demonstrating the effects of confining pressure on the cross section shape of the jet is established, and the calculation model for impact pressure of jet under confining pressure is also set up. Through example calculation and analysis, the rules governing the effects of confining pressure on external boundary shape of jet is concluded, such as the impact pressure of the jet exerted on the work face when the jet action is constant will decrease remarkably with the increase of the confining pressure, when the confining pressure increases to a certain value, it has more effects on the impact pressure of the basic section of the jet than on that of the initial section of the jet; and higher drilling fluid density will, to some extent, help to reduce the effects of confining pressure on well bottom jet, etc. These concluded findings are significant for understanding the jet properties under the high confining pressure in deep wells, and improving the jet drilling theory.更多还原