鄂尔多斯盆地巴汗淖地区马五_6段碳酸盐岩C、O同位素特征及其成岩意义  

Characteristics of Carbon and Oxygen Isotope of Carbonatite and the Diagenetic Significance of the Ma5_(6^(th)) Member in Bahannao Area, the Ordos Basin, China

作　　者：田雯[1] 陈刚[1] 李文厚[1] 高路恒 杨甫[3,4] 白金莉 陈萌[1] 

机构地区：[1]西北大学地质系西北大学大陆动力学国家重点实验室,陕西西安710069 [2]延长石油集团研究院,陕西西安710069 [3]国土资源部煤炭资源勘查与综合利用重点实验室,陕西西安710016 [4]陕西省煤田地质有限公司,陕西西安710016

出　　处：《矿物学报》2016年第1期12-18,共7页Acta Mineralogica Sinica

基　　金：国家科技重大专项(编号:2008ZX05005-004-007HZ);中国地质调查局油气资源调查项目(1212011220761-03);大陆动力学国家重点实验室科技部专项经费重点课题(编号:BJ14252)

摘　　要：鄂尔多斯盆地北部巴汗淖地区马五6段为风化壳型碳酸盐岩地层,岩性以鲕粒灰岩、晶粒白云岩为主,次生孔隙发育,是重要的油气储集层。采用Finnigan MAT252气体同位素质谱仪分别对该段碳酸盐岩进行C、O同位素测试,详细分析了巴汗淖地区马五6段碳酸盐岩成岩环境及孔隙演化条件。样品分析结果表明:埋藏高温成岩环境使得δ18O值与奥陶纪海水的δ18O值相比明显偏负,且白云岩δ18O值与灰岩δ18O值相比偏负,主要是埋藏白云石化作用的结果;δ13C值与奥陶纪海水δ13C值相当,极个别数值偏负,说明研究区马五6段在成岩作用过程中受有机碳影响较小,表明成岩作用发生在浅-中埋藏条件下。研究区孔隙度、渗透率的相关关系明显,主要是大气淡水成岩作用的改造,优化了孔隙及渗流通道,提高了储层的物性。The Ma56 th member of Bahannao area in the north of the Ordos Basin is an important oil and gas reservoir; it is weathering crust type carbonate formation, the main lithologic being oolitic limestone and grain dolomite, secondary pore development. By using Finnigan MAT252 gas isotope ratio mass spectrometry, the carbon and oxygen isotope were determined. This article also analyzes the diagenetic environment and porosity evolution conditions for carbonate formation in Bahannao area. Results show that compared with the Ordovician, burial dolomitization environment of high temperature led to the water＇s δ^18O value obviously negative, and dolomite＇s δ^18O value negative compared with limestone＇s δ^18O value. The δ^13C value is considerable with Ordovician water＇s δ^13C value with very few numerical biased. Results reveal that the Ma56 th member is less influenced by organic carbon in the process of diagenesis, and diagenesis occurred under shallow-buried conditions. The transformation of atmospheric freshwater diagenetic optimize porosity and seepage channel, improved reservoir physical properties, and making the relation between the porosity and permeability of the study area obvious.

关 键 词：碳酸盐岩 C、O同位素 次生孔隙 白云石化作用 

分 类 号：P534.4[天文地球—古生物学与地层学] P597[天文地球—地质学]