吸附对页岩中气体临界参数的影响

页岩孔隙细小,气体存在吸附现象。应用毛管束模型,在考虑吸附的基础上,建立了气体临界参数变化计算模型,研究了气体组成、压力、孔隙半径等因素对气体临界参数变化的影响。研究发现:页岩有效孔隙半径随气藏平均压力的增加而增大;随着孔隙半径的减小,气体的临界温度和临界压力变化率明显增加;临界温度变化率和临界压力变化率随着压力减小而增加。研究对于页岩气藏储层评价和开发方案设计具有重要意义。

Effect of adsorption on Critical parameters of gas in shales

The Pore size in shales is very small, even in the scale of nanometer. Most of the gas in shales exists in the state of adsorption. The two characteristics may have some effect on the critical parameters of gas in shale gas reservoir. On the basis of rock capillary tube model, a new correction model for the calculation of gas critical parameter was built and the effect of gas component, pressure and temperature on gas Critical parameters was studied. The effective radius for gas flow increases with average reservoir pressure increasing because of the change of the thickness of adsorption layer in pores. The critical parameters increase with the decrease of pore size and the average reservoir pressure. The adsorption of shale gas has some effect on the critical parameters of shale gas. The result has great significance for the evaluation of shale gas reserve and the design of shale gas reservoir development plan.