页岩气分离器阀套式排污阀冲蚀特性研究

Study on erosion characteristics of valve sleeve blowdown valve of shale gas separator

为解决页岩气开采过程中砂粒经过分离器后对排污阀造成严重冲蚀的问题,以长宁页岩气田某井为例,基于FLUENT软件,采用数值模拟的方法模拟在不同速度、砂量、粒径、形状系数和阀门开度情况下砂粒对排污阀冲蚀特性,并评估影响排污阀冲蚀特性的主要因素,明确排污阀的冲蚀情况。结果表明:阀瓣与节流孔冲蚀破坏是造成排污阀失效的主要原因;随着阀门开度减小,阀内压差呈指数式增长,在阀瓣和节流孔处流速最大,砂粒形状系数减小,对阀门冲蚀越严重;基于敏感性分析,各因素对阀门冲蚀特性影响程度为:ξ_(l)(速度)=0.73,ξ_(m)(砂粒粒径)=0.71,ξ_(n)(砂量)=0.70,ξ_(q)(形状系数)=0.67。因此,建议通过增大阀门内部流通面积将流体流速控制在7m/s以内,提高除砂器除砂能力,避免粒径较大的砂粒(砂粒粒径>60μm)进入排污阀,将进入排污阀的砂粒粒径控制在60μm内,为现场设备评价优化提供有效手段。

To solve the problem of severe erosion caused by sand particles passing through separators during shale gas extraction,a well in Changning Shale Gas Field was taken as an example.Based on FLUENT software,numerical simulation was used to simulate the erosion characteristics of sand particles on the drain valve under different speeds,sand content,particle size,shape coefficient and valve opening.The main factors affecting the erosion characteristics of the drain valve were evaluated to clarify the erosion situation of the drain valve.The results indicate that the erosion damage of the valve disc and throttle hole is the main reason for the failure of the sewage valve.As the valve opening decreases,the pressure difference inside the valve increases exponentially,and the flow velocity is the largest at the valve disc and throttle hole.With the decrease of shape coefficient of sand particles,the erosion of the valve is more severe.Based on sensitivity analysis,the degree of influence of various factors on valve erosion characteristics is:ξ_(l)(Speed)=0.73,ξ_(m)(Sand particle size)=0.71,ξ_(n)(Sand content)=0.70 andξ_(q)(Shape coefficient)=0.67.Therefore,it is recommended to control the fluid flow rate to within 7 m/s by increasing the internal flow area of the valve,improving the sand removal ability of the desander,and preventing larger sand particles(sand particle size>60μm)from entering the sewage valve.The sand particle size entering the sewage valve should be controlled within 60μm,which provides an effective means for the evaluation and optimization of on-site equipment.