吸附势理论在煤层气吸附／解吸中的应用  

Application of Adsorption Potential Theory in the Fractionation of Coalbed Gas during the Process of Adsorption/Desorption

作　　者：苏现波[1] 陈润[2] 林晓英[1] 宋岩[3] 

机构地区：[1]河南理工大学,河南焦作454000 [2]中国矿业大学,江苏徐州221008 [3]中国石油勘探开发研究院,北京100083

出　　处：《地质学报》2008年第10期1382-1389,共8页Acta Geologica Sinica

基　　金：国家计划“973”项目(编号2002CB211705);国家自然科学基金项目(编号50534070);河南省生物遗迹与成矿过程重点实验室开放基金项目(编号otmp0806)资助成果

摘　　要：煤层气的吸附/解吸将导致煤层甲烷碳同位素以及煤层气多组分分馏,使得煤层气富集区预测成为可能;并为揭示注入CO2增强CH4产出提供依据。本文根据Polanyi吸附势理论和实测及收集的等温吸附试验数据,探讨煤层甲烷碳同位素和多组分气体的分馏。通过研究,得到如下两个结论:①13CH4在煤表面的吸附势普遍高于12CH4,也就是说13CH4与12CH4相比具有优先吸附、滞后解吸的特点。这种差异具有随压力增加而增加的特点。②煤层气吸附/解吸过程中CH4和CO2的分馏可归纳为以下3种情形:a.CO2和CH4的吸附/解吸等温线不相交,CO2的吸附势大于等于CH4,在CO2和CH4吸附势接近的中压阶段(1～2.5MPa)不利于注CO2驱CH4,高压、低压阶段均有利;b.因CH4的吸附/解吸等温线相交造成CH4和CO2的吸附特性曲线相交,在高压条件(>2.5MPa)下利于注CO2驱CH4;c.因CO2的吸附/解吸等温线相交造成CH4和CO2的吸附特性曲线相交,在高压条件(>2.5MPa)下利于注CO2驱CH4。吸附势理论的引入为定量评价注入二氧化碳驱甲烷工艺参数和有利储层的选择提供了方法,并揭示了在高压条件(>2.5MPa)下总是有利于向煤层注入CO2强化CH4产出。The adsorption/desorption of coalbed gas will result in the fractionation of methane carbon isotope and multi-component gases. Fractionation can make the possibility of predication of coalbed gas accumulation and reveal the mechanism of injection carbon dioxide to enhance methane recovery. Based on the Polanyi＇s adsorption potential theory and the adsorption/desorption isotherm data, the fractionations of methane carbon isotope and multi-component gases are discussed in this paper. Two conclusions can be summarized： （1） the adsorption potential of 13CH4 on coal is higher than that of 12CH4, especially at high pressure. It suggests that the coal is preference for 13CH4 adsorption and postponement for 13CH4 desorption; the fractionation of methane carbon isotope is intense at high pressure. （2） The fractionation of CH4 and CO2 during the process of adsorption/desorption can be generalized into three situations, a. the adsorption/desorption isotherms of CH4 and CO2 on/from coal is nearly parallel, and the adsorption potential of CO2 is equal to or larger than that of CH4. It implies that the coal is always preferable to carbon dioxide adsorption, but the fractionation is slight at medium pressure （1 ~2. 5 MPa）; b. the adsorption characteristic curves of CH4 and CO2 are intersectant because of intersection of CH4 adsorption/ desorption isotherms. It implies that the coal is preferable to carbon dioxide adsorption at high pressure （〉2.5 MPa）; c. the adsorption curves of CH4 and CO2 are intersectant because of intersection of CO2 adsorption/desorption isotherms. It shows that the coal is preference for carbon dioxide adsorption at high pressure （〉2. 5 MPa）. The mechanism of injection carbon dioxide to enhance methane recovery is perfectly characterized by adsorption potential theory. It indicates that it is always favorable for injection carbon dioxide to enhance methane recovery at high pressure （〉2.5 MPa）.

关 键 词：吸附势理论 甲烷碳同位素 多组分气体 吸附-解吸 分馏效应 

分 类 号：P618.11[天文地球—矿床学]