页岩有机质孔隙形成、保持及其连通性的控制作用  

Formation,preservation and connectivity control of organic pores in shale

作　　者：腾格尔 卢龙飞[2] 俞凌杰[2] 张文涛[2] 潘安阳[2] 申宝剑[2] 王晔[3] 仰云峰[2] 高志伟[3] BORJIGIN Tenger;LU Longfei;YU Lingjie;ZHANG Wentao;PAN Anyang;SHEN Baojian;WANG Ye;YANG Yunfeng;GAO Zhiwei(Oil&Gas Resources Survey,China Geological Survey,Beijing 100083,China;Wuxi Petroleum Geology Institute,Sinopec Exploration&Production Research Institute,Wuxi 214126,China;College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China)

机构地区：[1]中国地质调查局油气资源调查中心,北京100083 [2]中国石化石油勘探开发研究院无锡石油地质研究所,江苏无锡214126 [3]中国石油大学(北京)地球科学学院,北京102249

出　　处：《石油勘探与开发》2021年第4期687-699,共13页Petroleum Exploration and Development

基　　金：国家自然科学基金“页岩气改造-散失途径与保存条件”(41690133);国家油气科技重大专项“重点层系页岩气生成与储集机理研究”(2017ZX05036-002)。

摘　　要：针对页岩有机质孔隙发育的强非均质性及形成演化的复杂性,运用场发射扫描电镜、拉曼光谱和流体注入与CT/扫描电镜成像等实验技术,开展南方下古生界富有机质页岩显微组分、有机孔和连通性等分析,结合生排烃机制、有机质活性炭成孔机理等研究成果,探索有机孔发育与有机质类型、生烃过程、成岩作用和孔隙压力等内在联系,揭示页岩有机质孔隙的形成与保存机制及其连通性的控制因素。研究表明,①有机孔形成贯穿于生烃全过程,受制于有机质类型、成熟度和分解作用,干酪根与固体沥青的生烃组分及差异生烃演化造成不同的孔隙发育特征,有机孔主要发育于固体沥青和富氢干酪根;②有机孔保存受成熟度和成岩作用控制,包括烃类原位滞留的空间位阻效应、重结晶形成的刚性矿物格架、孔隙流体压力与页岩脆-延性转换的耦合支撑机制;③R_(o)值4.0%是有机孔消亡的成熟度门限值,指出R_(o)值大于3.5%的页岩层属于页岩气勘探高风险区,其低含气性归因于“先天不足”,烃源岩抬升前就处于开放状态,排烃效率高,芳构化强烈,使得成熟度升高,孔隙减少;④同一有机质颗粒内部孔隙具较好连通性,不同有机质孔隙及其与无机孔缝之间形成有效连通则取决于页岩有机质丰度、分布及孔缝发育程度,不同类型有机质高丰度聚集保存并呈纹层状分布是有机孔、粒缘缝和层理缝发育并连通成为有效储集层的先决条件。图14表3参29。In view of strong heterogeneity and complex formation and evolution of organic pores,field emission scanning electron microscopy(FESEM),Raman spectrum and fluid injection+CT/SEM imaging technology were used to study the macerals,organic pores and connectivity of organic pores in the lower Paleozoic organic-rich shale samples from Southern China.Combined with the mechanism of hydrocarbon generation and expulsion and pore forming mechanism of organic matter-based activated carbon,the relationships between organic pore development and the organic matter type,hydrocarbon generation process,diagenesis and pore pressure were explored to reveal the controlling factors of the formation,preservation and connectivity of organic pores in shale.(1)The generation of organic pores goes on through the whole hydrocarbon generation process,and is controlled by the type,maturity and decomposition of organic matter;the different hydrocarbon generation components and differential hydrocarbon-generation evolution of kerogen and solid asphalt lead to different pore development characteristics;organic pores mainly develop in solid bitumen and hydrogen-rich kerogen.(2)The preservation of organic pores is controlled by maturity and diagenesis,including the steric hindrance effect of in-situ hydrocarbon retention,rigid mineral framework formed by recrystallization,the coupling mechanism of pore-fluid pressure and shale brittleness-ductility transition.(3)The R_(o) of 4.0% is the maturity threshold of organic pore extinction,the shale layers with R_(o) larger than 3.5% have high risk for shale gas exploration,these shale layers have low gas contents,as they were in an open state before uplift,and had high hydrocarbon expulsion efficiency and strong aromatization,thus having the"congenital deficiency"of high maturity and pore densification.(4)The pores in the same organic matter particle have good connectivity;and the effective connectivity between different organic matter pores and inorganic pores and fractures depends on the abundance and

关 键 词：页岩气 有机质 孔隙 成熟度 生烃过程 成岩作用 奥陶系五峰组 志留系龙马溪组 四川盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探]