摘要
为完善页岩等量吸附热计算方法,明确页岩吸附超临界CH4的热力学特征,选用温度区间为26.85~199.85℃、压力范围为0.08~14 MPa的页岩等温吸附数据,系统检验常用吸附相密度计算方法的合理性,并基于绝对吸附量分析等量线标绘法的适用范围及页岩等量吸附热特征。结果表明:①经检验,常用的吸附相密度计算方法中Ozawa经验公式法适用于较宽温压范围内的绝对吸附量校正;②Lnp-1/T曲线在温度区间为149.85~199.85℃且nab为0.1038~0.2800 mmol/g时不具有线性特征,因此该温度及吸附量范围内等量线标绘法不再适用,同时Lnp-1/T曲线的nab取值应当与Lnp-nab曲线保持一致,以此获得的等量吸附热曲线才能全面地反映吸附过程的热力学特征;③页岩吸附超临界CH4的等量吸附热随着吸附量的增加呈现先增大后减小的非单调变化,表明在吸附早期,CH4分子间的相互作用力对等量吸附热的影响占主导,当吸附量增加到一定程度后,页岩表面的非均一性占主导。
In order to improve the calculation method of the isosteric adsorption heat,clarify thermodynamic characteristics of CH4,the shale isotherm adsorption data with temperature range of 26.85-199.85℃and pressure range of 0.08-14 MPa are selected to verify the rationality of the common calculation method of adsorption phase density,analyze the applicability of the adsorption isostere plotting method and the characteristic of isosteric adsorption heat of shale using absolute adsorption capacity.And the following research results were obtained.Firstly,Ozawa empirical formula is suitable for the correction of absolute adsorption capacity in a wide range of temperature and pressure.Secondly,in the temperature ranges from 149.85℃to 199.85℃,and nab ranges from 0.1038 mmol/g to 0.2800 mmol/g,the curve of Lnp-nab has no linear characteristic,so the adsorption isostere plotting method is not suitable in the above temperature and nab ranges.The nab value of Lnp-1/T curve should be consistent with that of Lnp-nab curve,so that the isosteric adsorption heat curve can fully reflect the thermodynamic characteristics of the adsorption process.Finally,the adsorption heat of supercritical CH4 on shale increases at first and then decreases with the increase of adsorption capacity.It shows that in the early stage of adsorption,the influence of the interaction between molecules of CH4 on the adsorption heat of supercritical CH4 is dominant.When the adsorption capacity increases to a certain extent,the heterogeneity of the shale surface is dominant.
作者
薛培
张丽霞
梁全胜
师毅
曹成
汤延帅
XUE Pei;ZHANG Li-xia;LIANG Quan-sheng;SHI Yi;CAO Cheng;TANG Yan-shuai(Research Institute,Shaanxi Yanchang Petroleum(Group)Co.Ltd.,Xi’an 710075,China;Shaanxi Key Laboratory of Lacustrine Shale Gas Accumulation and Exploitation,Xi’an 710075,China;Yanchang Petroleum Group Exploration Company,Yan’an 716000,China;Qilicun Oil Production Plant,Yanchang Oilfield Co.Ltd.,Yan’an 716000,China)
出处
《天然气地球科学》
EI
CAS
CSCD
北大核心
2020年第9期1261-1270,共10页
Natural Gas Geoscience
基金
国家科技重大专项(编号:2017ZX05039001005)
延长石油青年基金项目(编号:ycsy2020qnjj-B-06)联合资助。
关键词
页岩
过剩吸附量
吸附相密度
绝对吸附量
等量吸附热
Shale
Surface excess mass
Adsorbed phase density
Absolute adsorbed amount
Isosteric heat of adsorption
