The Fishbone Wells Nozzle Design And Experimental Study

The fishbone wells technology to develop an efficient,accurate and controllable connected reservoir in the new way,fishbone wells in oil and gas layers in time to a maximum of 300 branches,a big increase in reservoirs bare area,realize the improvement of production.In the field of high pressure jet technology research,because the abrasive jet has rock fragmentation threshold low pressure and high drilling efficiency,will gradually replace with the method of water jet.Therefore,this topic using abrasive jet drill new fish bone spurs well the exploitation of unconventional oil and gas research idea,to carry out the abrasive jet drilling technology and jet bit optimization design.This article mainly from the theory of pulse jet,the frequency of pulse jet characteristics,structure parameters and operation parameters on the self-excited effect and so on several aspects are studied.First,the mechanism of hydraulic pulse jet self-excited oscillation are discussed in this paper,analyzes the effective incentive conditions,and through the grid simulation method was deduced frequency characteristics of the self-excited oscillation pulsed jet device formula,this formula shows that the hydraulic pulse jet excitation effect mainly related to the oscillation cavity structure parameters and operation parameters.Secondly,the simplified model of self-sustained oscillation pulsed jet device is established based on the similarity principle of fluid mechanics and numerical simulations are conducted by CFD software.The large eddy simulation（LES）method is applied to simulate the flow field inside the oscillation chamber under the laboratory test conditions.The simulation results are quite supportive to the interpretation of the mechanism of self-sustained oscillation pulsed jet and the optimal range of structural parameters of oscillation chamber is obtained:d₂/d₁=1.2¹.5,D_c/d₁=5.0⁷.5,L_c/D_c=0.5⁰.8.Finally,the physical model tests of self-sustained oscillation pulsed jet device are carried out to verify the accuracy of numerical simulation results.The results of laboratory tests indicate that optimal range of structural parameters is generally in agreement with the numerical simulation results.In addition,the frequency characteristics of the pulsed jet are further analyzed and the calculation formula of pressure drop is derived according to experimental results.Based on the deep well drilling operation,the optimization design of hydraulic impact drilling tool with self-sustained oscillation pulsed jet is accomplished.