Numerical Simulation Of Erosion Behaviors Under Emergency Discharge Conditions When Drilling High Pressure And High Yield Gas Reservoir

In the emergency discharge process of high-yield gas wells,the production system will be affected by high-speed particle erosion and the wall wear will be reduced,which will lead to the reduction of the pressure bearing capacity of the equipment and even the erosion failure.According to the field measurements,the tubing string was measured in this paper.The flow model and erosion model suitable for emergency blowout prevention of high production gas wells were established by the structural parameters of wellhead device and surface throttling pipe.The flow field characteristics and erosion behavior of tubing string,wellhead device and surface throttling manifold were studied.It mainly involves the following contents:(1)Based on Lagrangian method and Euler method,the geometry models of tubing string,wellhead device and surface throttling pipe were established.The turbulent flow model and DPM erosion model suitable for this study were selected according to the actual working conditions in the field.The numerical simulation calculation method was determined,and the calculation model was checked and validated according to the erosion morphology and measurement data of the device in the field.(2)The erosion behavior of drilling four-way,conventional gas recovery tree and y-type gas recovery tree under typical working conditions was studied.The distribution of flow field,particle trajectory and erosion behavior of daily discharge and sunrise sand were revealed.The erosion behavior of conventional gas recovery tree and y-type gas recovery tree was compared and analyzed,and the perforation time of easy erosion weakness was calculated,and the protective measures to mitigate erosion were put forward.(3)The erosion behavior of pipes string under typical working conditions was studied.The variation law of string erosion behavior with the decrease of well depth was found,and the distribution of air flow field between drill pipe and drilling ring was revealed by the amount of daily discharge and sunrise sand.The effects of particle trajectory and wall erosion behavior were analyzed and the erosion rates of the inner wall of drill pipe,the outer wall of drill pipe and the inner wall of casing under the same working condition were analyzed,and the protective measures to reduce erosion were put forward.(4)The erosion behavior of two kinds of throttling pipe structures with or without spikes were studied under typical working conditions.The effects of daily discharge amount and sunrise sand amount on the distribution of flow field,particle trajectory and wall erosion behavior in the two structures were revealed.The particles locus and erosion rate of the lower and lower corrugated gate valve before and after installing the anti-prickle short throttle were compared and analyzed,and the protective measures to reduce the erosion were put forward.