西加拿大盆地都沃内(Duvernay)海相页岩油气富集机制研究  

Hydrocarbon enrichment mechanism of Duvernay marine shale in the Western Canada Basin

作　　者：窦立荣[1] 黄文松[1] 孔祥文[1] 汪萍[1] 赵子斌 DOU Lirong;HUANG Wensong;KONG Xiangwen;WANG Ping;ZHAO Zibin(Research Institute of Petroleum Exploration and Development,Beijing 100083,China)

机构地区：[1]中国石油勘探开发研究院,北京100083

出　　处：《地学前缘》2024年第4期191-205,共15页Earth Science Frontiers

基　　金：中国石油天然气股份有限公司科技专项“海外油气地质新理论资源评价新技术与超前选区研究(2023ZZ07)”和“海外气田开发关键技术研究(2021DJ3303)”。

摘　　要：西加拿大盆地上泥盆统Duvernay页岩是最大海侵期形成的一套页岩油气富集与生产层系。为明确Duvernay页岩油气富集控制因素,在Duvernay页岩地质背景分析的基础上,运用岩心、测井、薄片、扫描电镜、3D孔隙重建信息及有机地化资料,对有机质富集的沉积因素、流体分布、储层质量及影响因素进行了分析,认为Duvernay页岩油气富集主要受盆内成因的硅质页岩沉积环境、有机质热演化、页岩储层质量及稳定构造背景的共同控制。研究发现,Duvernay组为晚泥盆世的深水陆棚环境,岩性以泥灰岩、灰泥岩和泥页岩为主,可识别出10种岩石相,其中硅质页岩最为发育;Duvernay页岩中主要发育Ⅱ、Ⅲ型海相有机质,有机质热演化程度中等,处于凝析气-湿气阶段,因此凝析油含量高;油气主要富集在黏土级矿物形成的富含有机孔的硅质页岩中,孔隙类型以有机质孔和粒内孔为主,有效孔隙度占比高,连通孔隙非常发育且横向连续分布,并具有垂向上相互连通的特征;成岩作用改善了页岩储层物性,天然裂缝提高了页岩储层的渗透率,而稳定的构造发育特征是Duvernay页岩油能够较好地保存至今的关键。The Duvernay shale in the Upper Devonian is a formation of shale rich in oil and gas,created during the peak transgression period in the Western Canada Basin.This study aims to elucidate the factors influencing hydrocarbon enrichment in the Duvernay shale through the analysis of sedimentary elements,fluid distribution,reservoir quality,and drivers of organic matter enrichment.Utilizing data from cores,well logging,thin sections,scanning electron microscopy,3D pore reconstruction,and organic geochemistry,this research examines the geological context to determine that oil and gas accumulation in the Duvernay shale is governed by the sedimentary conditions of siliceous shale,organic matter thermal maturity,reservoir quality,and stable structural settings.The Duvernay Formation,situated in a deepwater shelf environment during the Late Devonian,comprises primarily marl,mudstone,and shale lithologies.it is observed that Type II and III marine organic matters are abundant in the Duvernay shale through the identification of ten lithofacies,with siliceous shale being predominant.These organic materials exhibit moderate thermal maturity,falling within the condensate to wet gas stage,leading to a high condensate to gas ratio.Oil and gas are predominantly found in siliceous shale with organic pores created by clay-grade minerals,showcasing organic and intra-granular pore types.The shale possesses high effective porosity,with well-connected and horizontally distributed pores that display vertical connectivity characteristics.Diagenesis enhances the physical properties of the shale reservoir,while natural fractures boost permeability.Ultimately,the preservation of Duvernay shale oil is heavily dependent on a stable structural setting.

关 键 词：西加拿大盆地 Duvernay页岩 岩石相 有机质热演化程度 油气富集机制 

分 类 号：P618.1[天文地球—矿床学] P744[天文地球—地质学] P744.4