三水盆地古近系布三段砂岩中碳酸盐胶结物特征及成因  

Characteristics and formation of carbonate cements of sandstones in Paleogene 3^(rd) member of Buxin Formation of Sanshui Basin

作　　者：唐鑫萍[1,2] 王冠群 钱茂路 张喜满[3] 杨博贤 Tang Xin-ping;Wang Guan-qun;Qian Mao-lu;Zhang Xi-man;Yang Bo-xian(Research Institute of Exploration and Development,Dagang Oilfield Company,CNPC , Tianjin 300280 China;PetroChina ( Tianjin ) International Petroleum Exploration & Development Technology Co.Ltd, Tianjin 300280 ,China;Chirm Southern Petroleum Ejcploration & Development Corporation ,CNPC ,Guangzhou 510220,China)

机构地区：[1]中国石油大港油田公司勘探开发研究院,天津300280 [2]中油(天津)国际石油勘探开发技术有限公司,天津300280 [3]中国石油南方勘探开发公司,广东广州510220

出　　处：《天然气地球科学》2019年第3期353-360,共8页Natural Gas Geoscience

基　　金：中石油科技项目"三水盆地石油地质综合研究"(编号:NFKT-2017-SSXMB-005)资助

摘　　要：为研究三水盆地布三段砂岩中碳酸盐胶结物的组成特点及成因,开展岩矿鉴定、成岩演化分析和同位素地球化学分析。结果表明:布三段砂岩中碳酸盐胶结物普遍含铁,矿物组成主要为铁方解石和铁白云石;碳酸盐胶结物的碳同位素(δ^(13)C)值分布范围较集中,在-6.4‰～-4.3‰之间,平均为-5.6‰,氧同位素(δ^(18)O)值分布范围为-15.5‰～-11.2‰,平均为-13.1‰,碳源分析表明其形成与有机脱羧作用有关;计算古盐度Z值分布范围为107.5～112.5,平均值为109.3,反映碳酸盐胶结物形成于淡水环境;计算古温度为78.5～108.8℃,平均值为91.8℃,结合成岩演化分析,推测碳酸盐胶结物总体形成于中成岩阶段早期;计算古埋深为1 850～2 800m,对比现今700～1 550m埋深,推测该段砂岩具有"曾经深埋、后期抬升"的特点,平均被抬升约为1 200m。In order to study the composition and formation of carbonate cements in the sandstones of 3rd member of Buxin Formation in the Sanshui Basin,rock and mineral identification,diagenetic evolution analysis and isotopic geochemistry analysis are carried out.The results show that carbonate cements in the sandstones are generally iron containing,mainly ferrocalcite and ankerite.The distribution range of carbon isotope(δ13C)values is relatively concentrated,ranging from -6.4‰ to -4.3‰,with an average of-5.6‰.The distribution range of oxygen isotope value(δ18O)is -15.5‰ to -11.2‰,with an average of -13.1‰.Carbon source analysis shows that the formation of the cements was related to organic decarboxylation.The distribution range of the calculated Z value of paleosalinity presents 107.5 to 112.5,with an average value of 109.3,reflecting that carbonate cements were formed in freshwater environment.The calculated paleotemperature ranges from 78.5 to 108.8℃,with an average of 91.8℃.It is deduced that carbonate cements were generally formed in the early stage of mesodiagenesis.The calculated paleo-burial depth is 1 850-2 800 m,while the present burial depth is 700-1 550 m,which reflects the characteristics of"once deep buried and later uplifted"of sandstone in this section.The average elevation is about 1 200 m.

关 键 词：碳酸盐胶结物 稳定同位素 成岩环境 成岩流体 三水盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探]