鄂尔多斯马家沟组膏盐岩-碳酸盐岩共生组合表生岩溶效果及意义  

The Effect of Supergene Karstification and Its Significance of the Gypsum-salt-Carbonate Paragenesis in Majiagou Formation of Ordos Basin

作　　者：白斌[1] 胡素云[1] 陶士振[1] 张道锋[2] 刘伟[1] 杨文敬[3] 张宝民[1] 刘新社[2] 刘燕[2] 熊平[4] 

机构地区：[1]中石油勘探开发研究院,北京100083 [2]中石油长庆油田分公司勘探开发研究院,陕西西安710018 [3]中石油长庆油田分公司勘探部,陕西西安710018 [4]长江大学工程技术学院,湖北荆州434020

出　　处：《长江大学学报（自然科学版）》2017年第3期7-12,15,共7页Journal of Yangtze University(Natural Science Edition)

基　　金：国家科技重大专项(2011ZX05004);中国石油勘探开发研究院青年基金项目(2012Y-007);湖北省自然基金项目(2013CFB394)

摘　　要：鄂尔多斯盆地中东部奥陶系马家沟组(Om)发育典型膏盐岩-碳酸盐岩共生体系,其一、三、五段主要发育蒸发岩,二、四、六段多为碳酸盐岩,表生溶蚀作用影响了盐上马家沟组五段(Om_5)1~4亚段风化壳储层的形成与分布,成为靖边大气田主力产层。区内对于膏盐岩-碳酸盐岩共生体系储层岩溶效果定量评价较少,溶蚀模拟试验也多为温度、岩石成份、岩石结构、流体性质等单因素对白云岩溶蚀机理的定性模拟。因此,以基于地质条件下的溶蚀模拟试验为基础,定量评价岩溶作用对膏盐岩-碳酸盐岩储层孔隙结构的影响,指出在常压、饱和CO_2水(3%~15%)、气温30℃的封闭体系下膏盐岩-碳酸盐岩共生组合溶蚀量与膏盐含量呈正相关关系,含盐白云岩、含白云质膏岩、白云质膏岩、膏质白云岩、含膏白云岩溶蚀率依次降低,溶蚀前后孔隙度至少增加6%。含盐白云岩溶蚀率最高,达19.8%,含膏白云岩溶蚀率最低,仅为6.3%。据此提出含盐白云岩、含白云质膏岩等膏盐岩-碳酸盐岩共生体系是Om有利储集岩,经岩溶作用后孔隙度最高可提高6%~20%,从而较好地解释了Om_5含膏云坪相带存在规模优质储层的原因,并为阐明膏盐岩-碳酸盐岩共生体系岩溶储层形成机理及分布预测提供了试验依据。The typical symbiotic gypsum-salt and carbonate paragenesis were developed in the Ordovician Majiagou Formation of Ordos Basin,in which the evaporated rocks were mainly developed in the First,Third and Fifth Members and the carbonate was mostly developed in the Second,Fourth and the Sixth Members of Majiagou Formation.In the 1-4submembers of the Fifth Member(Om_5),the formation and distribution of weathering crust were affected by supergene karstification,thus it became a major production zone in the Large Jingbian Gas Field.In the region,there was less quantitative evaluation on the effect of reservoir karstification of gypsum-salt-carbonate paragenesis,the research on the dissolution simulation experiments were mostly for its temperature,rock components,rock structures and fluid properties for the quantitative evaluation on the dissolution mechanism simulation of dolomites.Therefore,on the basis of dissolution simulation experiment under geological condition,the influence caused by supergene karstification on the pore structure of gypsum-salt and carbonate reservoirs was quantitatively evaluated,the positive correlation between the dissolution ratio of the gypsum-salt-carbonate paragenesis and gypsum-salt content under the closed system with normal pressure,CO2-saturated water(3%~15%)and temperature at 30℃was pointed out,the dissolution ratios of salt-bearing dolomite,the dolomite-bearing gypsum-salt,the dolomitic gypsum-salt,the gypsum dolomite and the gypsum contained dolomite were reduced orderly with porosity increase of 6%at least.The dissolution ratio of salt-bearing dolomite was the highest at 19.8%,while the dissolution ratio of the gypsum contained dolomite was the lowest at 6.3%.On the basis of the study,it is pointed out that the symbiotic gypsum-salt and carbonate systems like salt-bearing dolomite,dolomitebearing gypsum are favorable reservoirs in Majiagou Formation.The porosity can be promoted at the most level of 6%~20%after supergene karstification,it further explains why the dolomitic flat fa

关 键 词：鄂尔多斯盆地 马家沟组 膏盐岩-碳酸盐岩 表生岩溶 

分 类 号：TE122.2[石油与天然气工程—油气勘探]