旋进旋涡与V锥组合计量气液两相流实验研究

Experimental study on the measurement of gas-liquid two-phase flow by the combination of precession vortex and V-cone

目的解决低渗透气田在井间串联、井口混输计量模式下,单井产气、产液量无法准确计量的技术难题。方法基于旋进旋涡流量计和V锥流量计的单相计量原理,通过开展空气-水两相流的室内实验,分析了不同运行压力、气液比以及表观气速下单相流量计的混相计量误差变化规律。借助量纲分析法,分别建立了进动频率和压降与相关无量纲准数的关联公式,并采用室内实验数据分别进行了混相条件下的参数修正,利用两种流量计串联组合的方式,提出了一种适用于低含液率的湿气双参数组合计量模型,并采用延安气田现场的实流数据对模型计算精度进行了验证。结果室内实验时,当湿气体积含液率小于1%时,旋进旋涡进动频率随体积含液率的升高而降低,出现“欠读”现象,而V锥流量计的计量压降随体积含液率的升高而增大,产生“过读”现象。当体积含液率大于1%时,由于气相含液量偏大,造成旋涡进动信号下降规律不明显,从而导致组合计量模型的结果可能出现失真,现场实流测试结果显示,组合计量模型的气相体积流量的平均相对误差为2.029%,液相体积流量的平均相对误差为15.066%,体积含液率的平均绝对误差为0.059%。结论旋进旋涡与V锥流量计的组合计量模型在气相含液量较低时,气相和液相的计量精度可满足现场生产需要,且加工设计成本较低,可以为延安气田排水采气井的气液混相计量提供技术支持。

Objective The aim is to solve the technical problem that the gas and liquid produced by a single well cannot be measured accurately in the low permeability gas field with series between wells and mixed wellhead metering mode.Methods Based on the single-phase metering principle of the precession vortex flowmeter and V-cone flowmeter,the miscible metering error of the single-phase flowmeter was analyzed under different operating pressures,gas-liquid ratio and apparent gas velocity through the indoor experiment of air-water two-phase flow.Through the application of dimensional analysis,the correlation formulas of precession frequency and pressure drop,as well as relevant dimensionless number were established,respectively.In addition,the parameters under miscible conditions were modified utilizing laboratory experimental data.A two-parameter combined measurement model of moisture gas suitable for low liquid content was proposed by combining two flowmeters in series.The accuracy of the model was verified by using the real flow data of Yan′an gas field.Results The results showed that in laboratory experiments,when the liquid volume fraction of wet gas was less than 1%,the precession frequency of the precession vortex decreased with the increase of the liquid volume fraction,resulting in an“underread”phenomenon.In contrast,the V-cone flowmeter's metering pressure drop increased with the volume fraction of liquid,resulting in an“overread”phenomenon.When the liquid volume fraction of the V-cone flowmeter was greater than 1%,the liquid content of the gas phase was too large.As a result,the decline law of the vortex precession signal was not clear,and the results of the combined metering model may be distorted.The field real flow test results showed that the average relative error of the gas phase volume flow of the combined metering model was 2.029%,the average relative error of the liquid phase volume flow was 15.066%,and the average absolute error of the volume liquid content was 0.059%.Conclusions The combined measurement model of precession vortex and V-cone flowmeter is used when the liquid content of gas phase is low,the measurement accuracy of the gas phase and liquid phase can meet the needs of on-site production,and the processing design cost is low,which can provide technical support for the gas-liquid mismixing measurement of drainage gas production wells in Yan′an gas field.