摘要
页岩纳米孔隙中超临界甲烷的吸附相密度特征是明确页岩真实含气量的基础。基于伊利石纳米孔隙中甲烷吸附相的分子模拟数据,在温度333.15~423.15 K和压力0~90 MPa区间内,分别利用Langmuir三元模型法、过剩吸附曲线截距法、密度剖面积分法计算了甲烷吸附相的密度和绝对吸附量,分析温度、压力和孔径对甲烷吸附相的影响规律,系统检验甲烷吸附相密度计算方法的合理性。研究表明:1)温度的升高减弱了甲烷受到的孔壁吸引作用,降低了甲烷吸附相的密度和绝对吸附量;2)甲烷吸附相的密度和绝对吸附量随压力增大而增加,深层页岩中地层高压对甲烷吸附相的密度和绝对吸附量仍有重要影响;3)受甲烷吸附相扩展和孔壁耦合吸引作用影响,甲烷在2 nm和4 nm孔隙中的吸附相密度和绝对吸附量更大;4)基于分子模拟的积分法适用于深层页岩纳米孔隙中甲烷吸附相密度的确定和绝对吸附量的校正。研究结果对页岩气储量准确评价具有重要意义。
Adsorption phase density characteristics of supercritical methane in shale nanopores are fundamental to the determination of accurate shale gas contents.Based on molecular simulation of methane adsorption in illite nanopores,the Langmuir ternary model fitting method,excess adsorption curve intercept method and density profile integration method were utilized to calculate the methane adsorption phase densities and absolute adsorption capacities in the temperature range of 333.15-423.15 K and pressure range of 0-90 MPa.The effects of temperature,pressure and pore size were discussed,and the rationality of various calculation methods for adsorption phase densities was validated.The results show that:(1)The increase of temperature weakens the pore wall attraction towards methane,reducing the methane adsorption phase densities and absolute adsorption capacities.(2)The methane adsorption phase densities and absolute adsorption capacities increase with increasing pressure,the effects of pressure on the methane adsorption phase densities and absolute adsorption capacities remain significant at high pressures of deep shale gas reservoirs.(3)Due to the expansion of adsorption phases and the coupling attraction of pore walls,the adsorption phase densities and absolute adsorption capacities of methane in 2 nm and 4 nm pores are larger than those in pores with other sizes.(4)The integration method coupled with molecular simulations is suitable for the determination of methane adsorption phase density and absolute adsorption capacity in deep shale nanopores.The research results are of great significance for the accurate evaluation of shale gas reserves.
作者
杨琴
黄亮
周文
邹杰
王璐
刘逸盛
冯鑫霓
YANG Qin;HUANG Liang;ZHOU Wen;ZOU Jie;WANG Lu;LIU Yisheng;FENG Xinni(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China;College of Energy,Chengdu University of Technology,Chengdu 610059,China)
出处
《断块油气田》
CAS
CSCD
北大核心
2023年第5期799-807,共9页
Fault-Block Oil & Gas Field
基金
国家自然科学基金项目“川南龙马溪组页岩干酪根中气水赋存特征与孔隙变形机理”(52204031)
四川省自然科学基金项目“深层页岩变形孔隙中水-CH_(4)-CO_(2)微观赋存及动用规律”(2023NSFSC0947)
四川省自然科学基金面上项目“页岩油藏超前注CO_(2)原油动用规律及碳封存机理研究”(2022NSFSC0205)。
关键词
吸附相密度
绝对吸附量
甲烷
纳米孔隙
深层页岩
adsorption phase density
absolute adsorption capacity
methane
nanopore
deep shale
