摘要
为厘清鄂尔多斯盆地长8砂岩储层中碳酸盐胶结物的基本特征及其对储层物性的影响,综合运用铁氰化钾和茜素红混合液染色薄片、阴极发光和碳氧同位素等分析技术,对碳酸盐胶结物的矿物学和地球化学特征进行了研究。结果表明,长8砂岩储层主要发育3期碳酸盐胶结物,第一期(准同生期-成岩早期)碳酸盐胶结物以方解石为主,δ^(13)CPDB在-3.7‰^-2.4‰之间,δ^(18)OPDB为-10‰左右,其成因与碱性湖水中碳酸钙的过饱和相关;第二期(早成岩B期-中成岩A期)碳酸盐胶结物以铁方解石为主,δ^(13)CPDB为-14.8‰^-4.1‰,δ^(18)OPDB为-21.0‰^-13.2‰,其主要受有机质热催化作用形成的有机酸轻碳源的影响;第三期(中成岩B期)碳酸盐胶结物主要为铁白云石和铁方解石,δ^(13)CPDB为-9.5‰^-5.5‰,δ^(18)OPDB为-25.7‰^-22.3‰,其可能受有机碳源和早期碳酸盐胶结物发生溶蚀形成的无机碳源的共同影响。理论计算表明,碳酸盐胶结物导致长8砂岩储层孔隙度降低了约5.06%,其孔隙度损失率为12.05%~12.95%。该研究对有利砂岩储层的预测具有重要的借鉴意义。
In order to verify the characteristics of carbonate cements and their effects on reservoir properties,the potassium ferricyanide and alizarin red staining slices,cathodoluminescence and carbon and oxygen isotopes,were used to study the mineralogical and geochemical characteristics of carbonate cements in Chang 8 reservoir.The research results show that there are three periods of carbonate cements developed mostly.The first period of carbonate cements is mainly calcite,with ^13C ranging from -3.7‰ to -2.4‰ and ^18O about -10‰.Its formation is related to the over saturation of calcium carbonate in alkaline lake water,formed in penecontemporaneous to early diagenetic stage.The second period of carbonate cements is ferrocalcite,with ^13C ranging from -14.8‰ to -4.1‰ and ^18O-21.0‰ to-13.2‰.This is mainly due to the decarboxylation of organic matters during the period B of early diagenetic stage to period A of middle diagenetic stage.The third period of carbonate cements is mainly ferrodolomite and ferrocalcite,formed in the period B of middle diagenetic stage,with^13C being -9.5‰ to -5.5‰ and ^18O,-25.7‰to-22.3‰.This is affected by both organic carbon from the thermal evolution of organic matter and inorganic carbon formed by dissolution of carbonate cement in the early stage.Theoretical quantitative calculation shows that the porosity of Chang 8 reservoir is decreased about 5.06% by carbonate cement,with the loss rate of 12.05%-12.95%.The result has a reference to the prediction of favorable reservoirs.
作者
李阳
张文选
李树同
罗安湘
牟炜卫
邓秀芹
闫灿灿
惠潇
Li Yang;Zhang Wenxuan;Li Shutong;Luo Anxiang;Mou Weiwei;Deng Xiuqin;Yan Cancan;Hui Xiao(Key Laboratory of Petroleum Resources,Gansu Province/Key Laboratory of Petroleum Resources Research,Institute of Geology and Geophysics,Chinese Academy of Sciences,Lanzhou 730000,China;University of Chinese Academy of Sciences,Beijing 100049,China;Research Institute of Exploration ＆ Development,Changqing Oilfield Company,PetroChina,Xi＇an 710018,China)
出处
《地质科技情报》
CSCD
北大核心
2018年第4期175-183,共9页
Geological Science and Technology Information
基金
国家自然科学基金项目(41772142)
中国科学院兰州油气资源研究中心"十三五"创新基金项目(135CCJJ20160510)
关键词
碳酸盐胶结物
碳氧同位素
胶结期次
储层物性
长8储层
鄂尔多斯盆地
carbonate cement
carbon and oxygen isotopes
cementation stage
reservoir physical properties Chang 8 reservoir
Ordos Basin
