摘要
非常规油气自封闭成藏机理是全油气系统理论的核心。非常规油气自封闭作用力源于分子间相互作用,其表现形式与作用机制随储层介质及地质条件呈现差异化特征。本文通过阐述力的作用原理及尺度,明确了非常规油气储层特征及自封闭作用力类型,并定量表征自封闭作用力大小,形成以下主要成果与认识:(1)明确非常规油气自封闭成藏的本质是分子间作用力主导的非浮力过程,首次系统梳理出界面效应、限域效应与位阻效应三大作用机制,揭示了不同作用机制的原理与尺度特征。(2)厘清不同类型非常规油气自封闭作用力的影响因素,致密油气与游离态页岩油气的自封闭以兆帕(MPa)级毛细管力为主,受储层孔隙孔径、油-水界面张力及孔隙壁面润湿性控制;吸附态页岩油气与煤层气的自封闭则由限域效应下的分子吸附力主导,其吸附能受矿物表面性质、孔隙结构、温-压条件及储层流体特征共同影响。(3)建立储层孔隙孔径与油气分子尺寸相对大小控制下的自封闭效应模式,超致密储层孔隙(孔径与分子尺寸相当)以位阻效应为主,对大分子烃类形成机械阻塞;储层孔隙孔径为分子尺寸38倍以下时,油气差异吸附凸显,限域效应逐渐显现;储层孔隙孔径远大于分子尺寸时,孔隙界面效应成为主要的自封闭作用。研究成果系统阐述了非常规油气自封闭作用的各类分子间作用力类型及定量表征方法,深化了对自封闭成藏机理的认识,为非常规油气藏分布规律研究提供理论指导。
The mechanisms underlying the self-sealing accumulation of unconventional hydrocarbons form the core of the whole petroleum system(WPS)theory.Forces driving the self-sealing process originate from intermolecular interactions,and their manifestations and mechanisms vary with reservoir media and geological conditions.In this study,a series of results and insights are obtained through systematic investigation.Essentially,the self-sealing accumulation of unconventional hydrocarbons is a non-buoyancy process dominated by intermolecular interactions.For the first time,three major mechanisms behind the self-sealing accumulation are systematically identified:interfacial effect,confinement effect,and steric hindrance effect.The principles and scaling effects of these mechanisms are accordingly defined.Factors influencing the forces that drive the self-sealing of various unconventional hydrocarbon resources are determined.Specifically,the self-sealing of tight hydrocarbons and free shale hydrocarbons is predominantly driven by capillary pressure at megapascal(MPa)level,governed by the pore size,interfacial tension,and wettability of reservoirs.In contrast,the self-sealing of adsorbed shale hydrocarbons and coalbed methane(CBM)is primarily driven by molecular adsorption forces under the confinement effect,with the adsorption energy jointly influenced by mineral surface properties,pore structure,temperature and pressure conditions,and fluid characteristics.Models describing self-sealing governed by the relative sizes of pores and hydrocarbon molecules are established.These models reveal that under ultra-tight pores,where pore sizes are comparable to molecular sizes,the steric hinderance effect predominates,causing mechanical obstruction for large molecules.When pore sizes are less than 38 times molecular sizes,differential adsorption of hydrocarbons becomes significant,leading to the gradual emergence of the confinement effect.Conversely,when pore sizes are far larger than molecular sizes,self-sealing is primarily driven by the interfacial effect.This study presents a systematic elucidation of various types of intermolecular interactions involved in the self-sealing of unconventional hydrocarbons,along with methods for their quantitative characterization.The results of this study deepen the understanding of the mechanisms governing the self-sealing accumulation and offer a theoretical guide for research into the distribution patterns of unconventional hydrocarbon reservoirs.
作者
陈君青
贾承造
姜林
庞宏
火勋港
陈冬霞
施砍园
胡涛
杨晓斌
冉钧
CHEN Junqing;JIA Chengzao;JIANG Lin;PANG Hong;HUO Xungang;CHEN Dongxia;SHI Kanyuan;HU Tao;YANG Xiaobin;RAN Jun(State Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum(Beijing),Beijing 102249,China;Basic Research Center for Energy Interdisciplinary,College of Science,China University of Petroleum(Beijing),Beijing 102249,China;Research Institute of Petroleum Exploration&Development,PetroChina,Beijing 100083,China)
出处
《石油与天然气地质》
北大核心
2025年第4期1071-1091,共21页
Oil & Gas Geology
基金
中国石油科学研究与技术开发项目(2021DJ0101)
国家自然科学基金企业创新发展联合基金项目(U19B6003-02)。
关键词
分子间作用力
范德华能
位阻效应
限域效应
自封闭作用
全油气系统
成藏机理
非常规油气
intermolecular interaction
van der Waals force
steric hindrance effect
confinement effect
self-sealing effect
whole petroleum system(WPS)
hydrocarbon accumulation mechanism
unconventional hydrocarbons CHEN Junqing
JIA Cheng JIANG Lin
et al.Major types
