CO_2井筒相变流动温度压力计算模型研究

STUDY ON MODEL OF TEMPERATURE AND PRESSURE DISTRIBUTION IN CO2 WELL BORE FLOW INCLUDING THE FLUID PHASE CHANGE

CO2在井筒流动过程中的气液相变对井筒温度、压力分布的计算有较大影响。CO2流体在气液相变段的流动属于两相流动,目前常用的计算方法均未考虑该气液混合段的两相流计算。文章从传热学及两相流理论出发,建立了井筒流体相变过程中温度、压力分布的耦合计算新模型;考虑沸腾传热和凝结传热的影响,对流体相变过程中井筒总传热系数进行了修正。该模型主要创新在于可以对CO2流体相变过程中气液混合段的温度、压力进行求解,并能对该混合段气液组分含量变化的动态过程进行计算。运用此模型对吉林油田H75-29-7井压力、温度、质量含气率进行了计算,计算结果与实测结果对比显示本模型计算精度较高。

The CO2 phase change between liquid and gas in well bore flow has significant effects on temperature and pressure distribution in well bore.The flow of CO2 in the phase change section belongs to the two-phase flow.At present,the commonly methods did not take into account the calculation of the two-phase flow in the gas-liquid mixture section.Based on the theories of heat transfer and two-phase flow,a new pressure-temperature coupling calculation model was developed in this paper.The overall heat transfer coefficient was modified by considering the effect of boiling heat transfer and condensation heat transfer.The main innovation is that the model can calculate values of the temperature and pressure distribution and the dynamic changes of the gas-liquid component content in the gas-liquid mixture section during the process of the CO2 phase change.The pressure,temperature and dryness fraction of Well H75-29-7,Jilin Oilfield,were calculated using the new model.Comparisons of field testing data and computed data of pressure and temperature in Well H75-29-7 indicate that the new method is of high accuracy.