有机显微组成对泥页岩有机孔发育的影响——以川东地区海陆过渡相龙潭组泥页岩为例  

Influence of maceral composition on organic pore development in shale: A case study of transitional Longtan Formation shale in eastern Sichuan Basin

作　　者：曹涛涛 刘光祥[2] 曹清古[2] 邓模[2] 

机构地区：[1]湖南科技大学页岩气资源利用与开发湖南省重点实验室,湖南湘潭411201 [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

出　　处：《石油与天然气地质》2018年第1期40-53,共14页Oil & Gas Geology

基　　金：国家科技重大专项(2016ZX05061);中国石油化工股份有限公司科技开发部项目(P15103)

摘　　要：川东地区龙潭组发育一套海陆过渡相富有机质泥页岩,为了探讨该套泥页岩中有机孔发育特征及其影响因素,通过氮气吸附和氩离子抛光+扫描电镜等实验,获得了孔隙结构参数,分析了其与有机碳、矿物成分、镜质体反射率以及有机岩石学之间的关系。结果表明滨岸沼泽、潮坪潟湖和浅水陆棚相泥页岩矿物组成以粘土矿物为主,石英含量低;有机质以镜质组为主,其内有机孔发育很差,但在有机质内部及边缘发育一定量的微裂隙。深水陆棚相泥页岩具有高石英含量、低粘土矿物含量的特点,有机质以腐泥组和固体沥青为主,有机孔发育较好。滨岸沼泽、潮坪潟湖和浅水陆棚相泥页岩的微观孔隙体积与总有机碳(TOC)含量之间存在反向关系或相关性不明显;而深水陆棚相高TOC页岩具有比低TOC页岩更高的孔隙体积。综合文章及前人研究成果,认为在高成熟阶段,镜质组和固体沥青不是有机孔发育的主要贡献者,而腐泥组是有机孔发育的最有利的组成。因而,在对川东地区海陆过渡相甚至其他地区海陆过渡相泥页岩进行储层评价时,有机显微组分应该作为重要的影响因素被考虑在内。A sequence of organic-rich shale of transitional facies can be observed in the Longtan Formation of eastern Sichuan Basin. In order to investigate the characteristics of the organic pores and their controlling factors in the shale,we performed experiments and analyses on shale samples to study TOC,mineral composition,vitrinite reflectance,and organic petrological parameters through low-pressure nitrogen adsorption and scanning electron scanning combined with argon ion milling and etc. The results show that the mineralogy of shale samples from coastal-swamp,lagoon-tidal flat and shallow shelf facies is dominated by clay minerals with low content of quartz. The organic matters in the samples are mostly vitrinites with poorly-developed organic pores. However,some micro-cracks were found to occur within or along the rims of organic matter grains. In contrast,the shale of deep shelf facies was characterized by high quartz and low clay mineral contents and orgnic matters with well-developed pores being dominated by sapropelinite and solid bitumen. There is an inverse relationship or insignificant correlation between the microscopic pore volume and TOC of shale of the coastalswamp,lagoon-tidal flat and shallow shelf facies. In contrast,the pore volume is positively correlated with TOC for shale of deep shelf facies. In combination with previous works,we propose that vitrinite and solid bitumen are not the main contributors to organic pores during the high maturity stage of the samples,while sapropelinite is the most favorable for organic pore development. Thereforoe,the organic maceral composition should be taken into consideration when studying shalereservoir properties of this transitional facies in eastern Sichuan Basin as well as other areas.

关 键 词：有机孔 总有机碳含量 显微组成 龙潭组 川东地区 

分 类 号：TE122.2[石油与天然气工程—油气勘探]