高温高压下三元混合气体在储层岩心中的吸附等温线的测定

EXPERIMENTAL DETERMINATION OF ADSORPTION ISOTHERM OF THE TERNARY MIXED GAS IN RESERVOIR CORE AT HIGH TEMPERATURE AND HIGH PRESSURE

利用自行研制的XF - 1型高温高压气体吸脱附测试仪 ,结合一台色谱分析仪 (HP6 890 )、一套抽真空系统 ,测定了三元混合气体 (N2 -CH4 -C2 H6)在三个岩心中的总吸附等温线共计 6条 (累计测试点 111个 ) ,吸附平衡后自由气相组成、吸附相组成和多组分气体组分吸附量随压力的变化曲线各 18条 (累计测试点 16 8个 )。测试的温度为 5 0 .5℃。实验的结果表明 :①储层岩心介质对烃类混合气体的吸附现象是客观存在的 ,不容忽视 ;②岩心多组分气体吸附体系的吸附能力除受温度、压力影响外 ,更受到储层介质、岩石成分、结构和物性性质的影响 ;③烃类多组分气体吸附前后的组分发生了显著变化 ,高碳数的烃类组分比低碳数的烃类组分更易被岩心介质吸附 ;④多组分气体组分相对吸附量能有效地表征多组分气体中各组分气体的竞争吸附能力大小 ,依据这个指标可将三元多组分气体体系中各组分气体按其竞争吸附能力由强到弱排序为C2 H6>CH4 >N2 。

6 adsorption isotherms (with 111 measure points in total) of ternary mixed gas (N2-CH4-C2H6) in three cores and three groups of curves (each containing 18 curves, with 168 measure points in total) expressing the change of free-gas phase component, adsorption phase component or multicomponent gas adsorption vs pressure respectively after adsorption equilibrium were measured at the temperature of 50.5°C by use of self-developed Type XF-1 high temperature and high pressure gas adsorption-removal device, a chromatograph (HP6890) and a set of vacuum system. Experimental results indicate that (1) adsorption phenomenon of mixed hydrocarbon gas in reservoir core medium is an objective fact which can't be neglected in a real gas reservoir; (2) besides the influence of temperature and pressure, the multicomponent gas adsorption capacity in core can be more influenced by reservoir medium and the composition, structure and physical property of rock; (3) a distinct chan ge in the composition of multicomponent hydrocarbon gas occurs before and after adsorption and the hydrocarboncomponent with heavier number of carbons is easier to be adsorbed by core medium than the one with lighter number of carbons; and (4) the relative multicomponent gas adsorption capacity can effectively characterize the magnitude of competitive powers of various gas components in multicomponent gas and according to such an index the competitive powers of various gas components in the ternary mixed gas can be shown as C2H6 > CH4 > N2.