摘要
黄铁矿是富有机质页岩中广泛发育的一种矿物,对富有机质页岩的沉积环境判别与油气富集具有重要意义。通过薄片鉴定、X射线衍射(X-ray diffraction,XRD)、氩离子抛光、扫描电镜、岩石热解和气体吸附等技术手段,对鄂尔多斯延长组与松辽盆地青山口组富有机质页岩中黄铁矿及其对储层影响进行分析。结果表明:①鄂尔多斯盆地黄铁矿含量以及草莓状黄铁矿粒径均大于松辽盆地,其中延长组每组样品草莓状黄铁矿平均粒径介于13.79~18.1μm,粒径主要发育在10~22μm;青山口组每组样品草莓状黄铁矿平均粒径在2.83~14.92μm间,粒径主要发育在2~8μm。②鄂尔多斯盆地和松辽盆地黄铁矿含量同TOC(总有机碳)、S1+S2(生烃潜力)存在正相关。两个盆地平均孔径与黄铁矿含量成正比、与草莓状黄铁矿粒径呈反比。③鄂尔多斯盆地延长组富有机质页岩中草莓状黄铁矿为早期同沉积浅埋藏黄铁矿,黄铁矿沉积环境为浅水氧化环境;松辽盆地青山口组富有机质页岩中草莓状黄铁矿存在中成岩后深埋藏黄铁矿与早期浅埋藏黄铁矿两种,黄铁矿沉积环境为半深水硫化环境、浅水次氧化-氧化环境。黄铁矿可促进有机质富集与孔隙发育,草莓状黄铁矿晶间孔还可促进烃类富集,对页岩油勘探具有借鉴意义。
Pyrite is a widely developed mineral in organic-rich shale,which is of great significance to the identification of the depo-sitional environment and hydrocarbon enrichment of organic-rich shale.By means of thin section identification,XRD(X-ray diffrac-tion),argon-ion polishing,SEM,rock pyrolysis and gas sorption,the pyrite and its impacts of reservoirs in organic-rich shale in the Yanchang Formation of Ordos Basin and Qingshankou Formation of Songliao were analyzed.The results show these as follows.The con-tent of pyrite and the particle size of pyrite framboid in the Ordos Basin are larger than those in the Songliao Basin,the average particle size of pyrite framboid in each group of samples in Yanchang group is 13.79~18.1μm,and most are 10~22μm.The average parti-cle size of pyrite framboid in each group of Qingshankou Formation is 2.83~14.92μm,and most are 2~8μm.The pyrite content in the Ordos Basin and Songliao Basin is proportional to the value of TOC(total organic carbon)and S1+S2.The average pore diameter of the two basins is proportional to the content of pyrite and inversely proportional to the particle size of pyrite framboid.The pyrite framboid in the organic-rich shale of the Yanchang Formation in the Ordos Basin is in early sedimentary-burial diagenetic stage with a shallow water oxidation environment.In organic-rich shale of the Qingshankou Formation in the Songliao Basin,there are two types of pyrites framboid:post-diagenetic deep-buried pyrites and early shallow-buried pyrites.The depositional environment of pyrite is semi-deep water sulfide environment and shallow water sub-oxidation-oxidation environment.Pyrite can promote the enrichment of organic matter and the development of porosity,and the intercrystalline pores of pyrite framboid can also promote the enrichment of hydrocar-bons,which has reference significance for shale oil exploration.
作者
肖迪
戴朝成
白斌
卞从胜
董若婧
刘羽汐
许亚鑫
XIAO Di;DAI Chao-cheng;BAI Bin;BIAN Cong-sheng;DONG Ruo-jing;LIU Yu-xi;XU Ya-xin(School of Earth Science,East China University of Technology,Nanchang 330000,China;Research Institute of Petroleum Exploration and Development,PetroChina,Beijing 100083,China)
出处
《科学技术与工程》
北大核心
2023年第23期9888-9902,共15页
Science Technology and Engineering
基金
国家自然科学基金(42072186)
中国石油天然气股份有限公司科学研究与技术项目(2021-DJ2203)。
关键词
陆相湖盆
富有机质页岩
黄铁矿
古环境
延长组
青山口组
continental freshwater lake basin
organic-rich shale
pyrite
paleoenvironment
Yanchang Formation
Qingshankou Formation
