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在气井的加砂压裂测试过程中，由于压裂作业遗留在井筒和地层返出的支撑剂，随着高速流动的天然气和压裂液的混合流体进入测试管道，形成高速含砂射流，它对管道及其附件造成非常严重的破坏。通过损坏机理分析，结合现场生产实际，在气井的加砂压裂测试地面流程中，使用耐磨的硬质合金材料和优化油嘴、堵头等管件的结构，改变其冲击角，可减少流体对管件的冲蚀破坏。在节流上游段使用分离沉砂装置，收集井筒和地层返出的支撑剂，减少其在流体中的含量。在放喷出口处采用堵塞三通，消耗砂粒的冲击动能，减少砂粒对管壁的冲蚀破坏。上述技术经在现场使用，分离沉砂装置可收集98％以上的砂粒，大大地减少地面流程中支撑剂的含量。硬质合金的使用和管件结构的优化，增强了其耐磨性。堵塞三通的应用，减少了对管壁的冲蚀破坏。三种技术可将流程安全控制时间延长数十倍以上，且成本被控制在比较合理的水平，从而达到了安全、经济生产的目的。

Safety Control Technique in Surface Flowing Process in the Later Stage of Sand Fracuring Testing

In the sand fracturing testing process of gas well,a high speed sandy jet flow,which makes the pipe and its fittings be seriouly damaged,may be formed because the propping agent,left at downhole or returned from reservoir owing to sand fracturing,enters into the testing pipe a long with the high speed flowing natural gas mixed with fracturing fluid.Throug h analyzing the damage mechanism and in combination with on site measurement,th e erosion by the fluid on pipe fittings may be reduced in the surface flowing pr ocess of sand fracturing testing of gas well by use of anti abrasive carbide al loy material and optimizing the structures of the pipe fittings,as choke and plu g,etc.,to change their impact angles;and at the upstream section of throttling,a separarion sand settling device is set up to collect the propping agent coming from the borehole and reservoir so as to decrease its content in fluid;and a pl ugging tee is installed at the gas vent to decrease the erosion and damage by sa nd grains on pipe wall through consuming sand grains' impact energy.According to the results of utilizing these techniques on the spot,it is shown that more tha n 98% sand grains were collected by the separation sand settling device,thus gr eatly reducing the agent content of the fluid in surface flowing process;the abr adability has been strengthened through utilizing carbide alloy material and opt imizing the structures of pipe fittings;and the erosion by sand grains on pipe w all was reduced by use of the plugging tee.The safety control time of the surfac e pipe and its fittings will be lengthened by several tens by utilizing the thre e techniques and a reasonable cost has been controlled,thus meeting a demand for safety.