南方海相页岩气赋存状态演化规律  

Evolution characterization of marine shale gas occurrence state in South China

作　　者：纪文明[1,2] 朱孟凡 宋岩 姜振学[3] JI Wenming;ZHU Mengfan;SONG Yan;JIANG Zhenxue(Key Laboratory of Deep Oil and Gas,China University of Petroleum(East China),Qingdao 266580,China;School of Geosciences,China University of Petroleum(East China),Qingdao 266580,China;Unconventional Petroleum Research Institute,China University of Petroleum,Beijing 102249,China)

机构地区：[1]中国石油大学(华东)深层油气重点实验室,山东青岛266580 [2]中国石油大学(华东)地球科学与技术学院,山东青岛266580 [3]中国石油大学(北京)非常规油气科学技术研究院,北京102249

出　　处：《中南大学学报（自然科学版）》2022年第9期3590-3602,共13页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(41821002,42172158);山东省重点研发计划项目(2020ZLYS08)。

摘　　要：首先,基于Langmuir方程,以高温和高压状态下甲烷等温吸附实验为基础,利用多元线性回归法,建立温度和压力耦合控制的扩展Langmuir方程,计算储层不同温度和压力条件下页岩吸附甲烷能力;其次,基于实际气体状态方程,计算地下储层温度和压力条件下最大游离气含量;最后,结合地层埋藏史,建立南方海相页岩气赋存状态演化模式。研究结果表明:随深度增加,在温度和压力耦合控制下,页岩吸附甲烷能力先增加后降低;随有机碳质量分数(w(TOC))增大,页岩吸附甲烷能力增加,达到最大吸附能力时的深度也随之增加;根据吸附气与游离气赋存比例,从地表到地下可依次划分出混合气带、吸附气带和游离气带;南方海相页岩气赋存状态演化过程可划分为4个阶段,即早期生物游离气阶段、热解吸附气阶段、热解游离气阶段和游离气吸附阶段;地层达到最大埋深后开始抬升,生气过程停止,游离气储集能力开始逐渐降低,页岩吸附能力逐渐增加。若页岩地层保存条件差,游离气不断散失,页岩储层中将以吸附气为主(渝东南地区);若保存条件好,则游离气得以保存,形成超压,页岩气将以游离气为主(焦石坝地区)。Firstly,based on Langmuir equation and methane isothermal adsorption experiment at the condition of high temperature and pressure,the extended Langmuir equation controlled by temperature and pressure coupling was established by multiple linear regression method to calculate the methane adsorption capacity of shale reservoir under different temperature and pressure conditions.Secondly,based on the state equation of real gas,the maximum free gas content under the temperature and pressure conditions of the underground reservoir was calculated.Finally,combined with the burial history,the evolution model of the occurrence state of marine shale gas in southern China was established.The results show that with the increase of depth,the methane adsorption capacity of shale increases first and then decreases under the control of temperature and pressure coupling.With the increase of w(TOC),the methane adsorption capacity of shale increases.When the maximum adsorption capacity is reached,the depth also increases.According to the occurrence ratio of adsorbed gas and free gas,it can be divided into mixed gas zone,adsorbed gas zone and free gas zone from the surface to the underground.The evolution process of shale gas occurrence state can be divided into 4 stages,including early biological free gas stage,thermal desorption gas stage,pyrolysis free gas stage and free gas adsorption stage.The formation starts to lift after reaching the maximum burial depth,the gas generation process stops,the free gas storage capacity begins to decrease gradually,and the shale adsorption capacity gradually increases.If the preservation conditions of the shale formation are poor,free gas is continuously lost and the shale reservoir will be dominated by adsorbed gas(southeast Chongqing area).Under good preservation conditions,free gas can be preserved,resulting in overpressure,and shale gas will be dominated by free gas(Jiaoshiba area).

关 键 词：页岩气 吸附能力 LANGMUIR方程 赋存状态 

分 类 号：TE122.2[石油与天然气工程—油气勘探]