摘要
以渤海湾盆地济阳坳陷沙河街组咸化湖盆页岩为研究对象,用扫描电镜(SEM)、阴极发光(CL)以及能谱分析(EDS)等多种手段,系统研究自生矿物特征及其对微观孔隙演化的控制机制。研究表明:①粗晶或次生加大方解石在碱性成岩环境下大量沉淀,导致孔隙度显著下降。②虽然成岩白云石含量低且呈分散状,但碱性胶结阶段酸性流体改造作用的减弱,间接抑制了孔隙保存。③铁白云石多形成于富亚铁离子(Fe^(2+))的酸性环境,常与伊利石化及钠化作用伴生。钠长石和铁白云石虽本身不直接作为孔隙载体,却与面孔率呈显著正相关,体现了酸性流体改造与矿物转化的协同效应。④伊利石是重要的孔隙载体,其片状或纤维状集合体在酸性环境中有助于粒间孔、层理面及微裂缝孔隙的形成与连通。⑤自生石英除细微充填形态外,还可形成特殊的脉状集合体,为周围孔隙结构提供刚性支撑,减缓后期压实作用和胶结作用对孔隙的破坏。⑥沙河街组页岩孔隙演化受酸性阶段“溶蚀-增孔”和碱性阶段“胶结-减孔”交替主导,不同自生矿物组合及其空间分布可作为评价储层孔隙保存潜力的重要指标。
This study focuses on the saline lacustrine shales of the Shahejie Formation in the Jiyang Depression,Bohai Bay Basin.Using a range of techniques,including scanning electron microscopy(SEM),cathodoluminescence(CL),and energy-dispersive spectroscopy(EDS),we systematically investigate the characteristics of authigenic minerals in the shales and their influence on micro-pore evolution.The results indicate that coarse-grained calcites or calcites with epitaxial overgrowth precipitated substantially in an alkaline diagenetic environment,leading to significantly reduced porosity.The diagenetic dolomites,in spite of low content and scattered distribution,also indirectly hindered pore preservation due to the weakened reworking by acidic fluids during cementation in an alkaline environment.Ankerites are mostly formed in a Fe^(2+)-rich acidic environment,frequently associated with illitization and albitization.Albites and ankerites exhibit pronounced positive correlations with thin-section porosity,although they are not direct pore carriers themselves.This relationship reflects the synergistic effects of acidic fluid-induced reworking and mineral transformation.Illites act as important pore carriers,and their platy or fibrous aggregates facilitate the formation and interconnectivity of intergranular pores,bedding-plane pores,and microfractures in an acidic environment.Authigenic quartz,except for some tiny quartz grains that fill pores,can occur as distinctive vein-like aggregates that provide rigid support for surrounding pore structures,thereby mitigating the damage to pores caused by subsequent compaction and cementation.Overall,the pore evolution in the shales of the Shahejie Formation is dominated by alternating dissolutioninduced porosity enhancement in an acidic environment and cementation-induced porosity reduction in an alkaline environment.Furthermore,various authigenic mineral assemblages and their spatial distributions can serve as important indicators for assessing the potential for pore preservation in shale reservoirs.
作者
李军亮
刘惠民
魏晓亮
张奎华
张鹏飞
秦峰
王勇
张顺
李政
刘鑫金
王伟庆
孟伟
LI Junliang;LIU Huimin;WEI Xiaoliang;ZHANG Kuihua;ZHANG Pengfei;QIN Feng;WANG Yong;ZHANG Shun;LI Zheng;LIU Xinjin;WANG Weiqing;MENG Wei(Exploration and Development Research Institute,Shengli Oilfield Company,SINOPEC,Dongying,Shandong 257015,China;State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Efficient Development,Dongying,Shandong 257015,China;Shengli Oilfield Company,SINOPEC,Dongying,Shandong 257001,China;Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 102206,China;Postdoctoral Scientific Research Station,Shengli Oilfield Company,SINOPEC,Dongying,Shandong 257015,China)
出处
《石油与天然气地质》
北大核心
2025年第6期1980-1997,共18页
Oil & Gas Geology
基金
国家自然科学基金项目(U24B6002)
国家油气重大专项(2024ZD1405101)
中国石化科技攻关项目(P23084,P24027)。
关键词
孔隙演化
酸-碱交替成岩
自生矿物
页岩
咸化湖盆
沙河街组
济阳坳陷
渤海湾盆地
pore evolution
alternating acidic and alkaline diagenesis
authigenic mineral
shale
saline lacustrine basin
Shahejie Formation
Jiyang Depression
Bohai Bay Basin
