水力喷射孔内射流增压规律数值模拟研究

NUMERICAL SIMULATION OF PRESSURE BOOSTING EFFECT IN JET HOLE DURING HYDRA-JET FRACTURING

水力喷射压裂过程中,高压射流会使水力射孔孔道内压力高于环空压力,形成孔内射流增压。孔内射流增压值是进行地面泵压预测和套管压力控制的基础。由于受到实验条件的限制,地面很难获得实际工况下的孔内射流增压值,因此,文章采用计算流体力学(CFD)方法,建立了二维水力喷射流场物理模型,模拟得到了实际工况下水力喷射孔内射流增压值以及喷嘴压降、环空围压和入口面积比对孔内射流增压的影响规律。结果表明,在实际施工参数条件下,孔内射流增压值可达10.7～12.5 MPa;喷嘴压降和入口面积比是影响孔内射流增压的两个主要因素,而环空围压对孔内射流增压没有影响。

During hydra-jet fracturing,the pressure in jet-hole is larger than annulus pressure under water jet effect,termed as Pressure Boosting Effect'.Acquiring pressure boosting value is the basic of pump pressure prediction and annulus pressure control.However,because of experimental limitation,it is difficult to get the value in actual working condition.This paper mainly discussed the regularity of pressure boosting affected by nozzle pressure drop,annulus pressure and area ratio,using Calculated Fluid Dynamic(CFD) method.CFD simulation result showed that main factors influencing pressure boosting are nozzle pressure drop and area ratio.However,annulus pressure does not influence pressure boosting value.Besides,under actual working condition,the pressure boosting value could reach 10.7~12.5 MPa.