Study On Jet Sand Washing And Flushing Technology For Low Pressure Lost Circulation Wells

In the process of oil production,sand grains in the formation will fall off from the formation along with the erosion of produced fluid.As the produced fluid enters the production well together and deposits in the well,a large number of sand deposits in the well will cause oil layer blockage,resulting in the decrease of oil production and even no oil production.And fine sand particles will enter the production equipment along with the produced fluid,causing serious wear and tear of the equipment,causing unnecessary losses.In this paper,based on the previous research results,combined with the actual requirements,the jet pump downhole flow field model is established.Through a series of numerical simulation analysis and experimental research on the new jet pump sand flushing system,the theoretical and practical basis is provided for the structural optimization of jet pump and improving the efficiency of jet pump.This paper studies the influence of jet pump flow rate ratio,area ratio,sand disturbing nozzle,different suction angle,sand washing liquid property and sand particle parameters on jet pump flow field.Through the numerical simulation study of single-phase flow and solid-liquid two-phase flow fluent,it is found that after adding sand disturbing nozzle,the flow rate ratio m of jet pump is mainly determined by the structure of the two nozzles.When the two nozzles are similar in structure,the flow rate ratio is equal to the square ratio of the outlet diameter of the two nozzles.The matching relation between the flow ratio and the area ratio has an important influence on the performance of the jet pump.A suitable matching will make the jet pump more energy-saving and the optimal combination is:the area ratio r is 0.5 and the flow ratio m is 0.2.The addition of the sand-disturbing nozzle has no obvious influence on the velocity flow field in the throat and will not affect the low pressure adsorption at the throat and the mixing process in the throat.Too large sand particles will also cause the jet pump to be unable to complete the sand washing and flushing work.When the angle of the suction chamber is 60°,the jet pump has higher efficiency at different flow ratios.Under the same conditions,when clear water is used as sand washing liquid,the jet pump efficiency is the highest,followed by guard sand washing liquid,and xantham is the worst additive for sand washing liquid.Finally,the accuracy of the numerical simulation results was verified by experimental means,and the best scheme to improve the efficiency of sand washing and flushing by jet pump was obtained,and the flow mechanism of the internal and downhole flow fields of the new double-nozzle jet pump was further mastered.