Research On The Erosion Of Throttle Chokes In Gas Well Testing

During the oil and gas wells test production process,the throttle nozzle is used to form back pressure to formation and effectively control the formation pressure.Fracturing outlet liquid is often high pressure air or liquid carrying perforated debris、 fractured sand and other solid particles,especially in the process of back spray.The velocity of the fluid rapidly rising when it goes through the throttle nozzle,and then it makes serious erosive wear to the nozzle.It has important significance to research the fluid flow and erosion of the chokes for protecting workers and equipment.Due to the bad working condition,experiment method can’t be effectively used in this research.In this research,the erosion model is repaired by the experiment data.And then numerical simulation is used to study the flow of the fluid and the process of erosive wear about the throttle nozzle.At the end of the research,a new multi-hole choke has been found.The results demonstrate that at the inlet face、outlet face and near the outlet face of the pipe,the erosive wear is severe.The mechanism of erosion is brittle impact at the inlet with big angle,shear erosion at the nozzle core surface and rotary grinding at the outlet face with small angle.Before the critical pressure ratio,downstream flow has an impact on the upstream.After the critical pressure ratio,the throttle effect is enhanced,and the high-speed jet is formed at the outlet of the nozzle core.It has an obvious decline of gas temperature in the central of the pipe which can easily produce natural gas hydrate.Under the equivalent area for gas through,the swirl nozzle has the best throttling ability,and then is the fixed nozzle,the needle nozzle has the worst throttling ability.At the last of the research,a new style of fixed nozzle is presented which has multi-holes.The result of the calculate simulation shows that the center hole structure is superior to the circumferential perforation structure.At the same time,the new fixed nozzle has excellent performance about resistance to erosion and temperature drop.