多孔介质吸附对凝析油气相平衡的影响

EFFECT OF POROUS MEDIUM ADSORPTION ON CONDENSATE-GAS PHASE EQUILIBRIUM

凝析油气相平衡过程发生在地层的多孔介质中。多孔介质由于其巨大的比面积而具有较强的吸附能力，流体因而以吸附态和自由态两种状态存在。在常规相平衡分析的基础上，应用气体吸附理论，建立了地层条件下混合气体在储层多孔介质表面吸附时对相平衡影响的数学模型，提出了考虑多孔介质吸附的相平衡计算方法，并通过实例计算分析了多孔介质吸附对相平衡的影响，结论：凝析油气渗流应考虑多孔介质的吸附作用；重烃组分优先吸附，随压力降低解吸的重烃组分比轻烃组分多；吸附量随温度增高而降低；气藏孔隙度愈低，吸附态气体相对愈多。

The condensate gas phase equilibrium process takes place in the porous media of deep strata.Owing to their giant specific area,the porous media are of a relatively strong adsorption capacity and the fluid exists as two states,i.e.adsorption state and free state.Based on the conventional phase equilibrium analysis and by use of the theory of gas adsorption,a mathematical model of the effect of the mixed gas,adsorbed on the surface of porous media under formation conditions,on the phase equilibrium is set up,a phase equilibrium calculation method of considering porous medium adsorption is proposed and through an example calculation the effect of the porous medium adsorption on the phase equilibrium is analyzed.It is concluded that the adsorption of porous media should be considered in the percolation of the condensate and gas;heavy hydrocarbon component is prior adsorbed and the desorption heavy hydrocarbon component is more than the desorption light one along with pressure decrease;the adsorbance decreases along with temperature increase;and the lower the reservoir porosity,the more the adsorbed gas.