Study On Erosion-Resistance Of Materials For Hydraulic Jetting Tools

In recent years,with the promotion and implementation of large-scale fracturing technology in shale gas、tight oil and gas,as well as the low permeability、low permeability oil and gas field,the sand content and the displacement of the pump is more and more big in hydraulic fracturing process,fracturing tools will be inevitably bear the erosion from the high speed liquid-solid two-phase flow.The erosion resistance of 35 Cr Mo and cobalt base alloy materials of hydraulic jet fracturing tools were studied in this paper.The erosion rules of 35 Cr Mo and cobalt based alloy materials was studied by jet type experimental device in solid-liquid two-phase fluid consisting of 0.2% hydroxypropyl guar solution and quartz sands.The erosion rate was calculated by loss method and erosion surface conditions were analyzed by scanning electron microscope.The experimental results show that the erosion rate of 35 Cr Mo material increases first and then decreases with the increase of the impact angle.The surface erosion of 35 Cr Mo is the most serious when the impact angle was 45°.The erosion rate of 35 Cr Mo material and cobalt based alloy material were increased with the increase of flow rate,but the increase trend of 35 Cr Mo was more obvious.With the incident velocity increases 35 Cr Mo steel has a critical velocity value.The critical speed is about 8.2m/s,when the flow rate is higher than the critical value,the erosion rate increased highly with the incident velocity increased.When the sand content was in 50kg/m3~100kg/m3,the erosion rate of 35 Cr Mo material increases with the increase of sand content,when the sand content reached 100kg/m3,erosion rate reached a maximum.Then with the increase of the content of quartz sand,the erosion rate of 35 Cr Mo material began to stabilize.The erosion rate of cobalt based alloy material steadily and slowly increased with the sand content increased.The erosion of solid-liquid mixed solution on 35 Cr Mo steel is mainly mechanical erosion,damage mechanism of materials were the "cutting" and "impact forging.When the impact angle was small the damage mechanism is mainly micro cutting,large impact angle was impact forging.Cobalt base alloy loss forms continue to impact the formation of quartz sand surface fatigue crack,crack propagation in the subsequent process of erosion,which led to the loss of material.