Numerical Simulation And Experimental Research Of Selfrotating Jet Nozzle In Radial Drilling

Radial hydraulic jet drilling technology is a new method applied in the improvement of oil well output.The so-called radial hydraulic jet drill is drilling a plurality of straight wells along the radius direction of radial horizontal well in the same reservoir plane,which could greatly increase well drainage area in order to improve production and reduces the cost.It is an important economic exploitation means to improve the low permeability oil and gas reservoir.Through the overview of domestic and foreign research status,Introduce the construction process of radial drilling operations,analyze the characteristics of jet nozzles at home and abroad to provide ideas for the design of this subject.Starting from the theory of water jet to the research focus CFD numerical simulation analysis,introduce the research methods and technical route of CFD,Optimized the key parameters of optimal nozzle layout,flow channel shape of nozzle and nozzle exit section length diameter ratio by CFD numerical simulation.3 forward nozzles and 2 backward,circular-cone mixed inner flow channel type and 3.5~4.0 nozzle exit section length diameter ratio were established.After analyzing the flow field inside and outside the nozzle,the flow velocity distribution of the nozzle is obtained.It is found that the diameter of the front nozzle is too small and the injection rate is lower,for this problem,the optimal nozzle diameter allocation is obtained after modified of the model,the diameter of the forward nozzle is 0.6mm,0.8mm and 0.7mm,and the backward nozzle diameter is 1.2mm.Under the total flow of 30L/Min,flow rate of the forward jet is 11.89L/Min and backward jet is 18.11L/Min.Using the Fluid-Structure Interaction model to analysis the rock breaking procedure of radial hole drilling jet nozzle,with the Computational Fluid Dynamics result of inside and outside flow field import into Structural Mechanics,a precise numerical simulation analysis of jet rock breaking could be observed.The results indicating that the front nozzle jet is formed on the target body with 2 layers of shear broken ring,and the deformation range is larger than that of the nozzle outside,which is reasonable for the space layout of forward nozzles.The maximum shear stress of water jet at rock is 6.93 MPa,For hard sandstone which the compressive strength is 60.25 MPa,according to the rock shear strength failure theory,the jet has been able to break rocks.The indoor test result shows that under the pump pressure at 40 MPa,flow rate at 30L/Min,The nozzle produce capable water jet of breaking rock and the diameter of the inscribed circle of the rock breaking craters over the nozzle diameter,shows that the design scheme is effective used for rock breaking.