摘要
鄂尔多斯盆地奥陶系马家沟组马五段发育一套风化壳储层。通过岩心、岩石薄片、阴极发光、电子探针、碳与氧同位素和物性测试等实验分析并与中部气田区同类储层对比,研究了富县地区风化壳储层特征和形成演化规律,发现膏质结核溶模孔是本区最主要的储集空间,溶孔充填物多样且充填程度差异较大。研究认为:沉积相直接影响孔隙度大小(结核溶孔大小与数量),并间接影响储层渗透性(孔间释压裂缝的发育程度);表生期成岩作用决定储层的储集性能,大气淡水的选择性溶蚀构建溶孔轮廓,古地貌低部位孔隙被方解石完全充填;埋藏期成岩改造作用有限。明确了有利储层分布于马五段沉积期含膏云坪相和岩溶古地貌高部位叠置区域。沉积相和古地貌的精细描述是下一步有利储层预测的关键。
There is a set of weathering crust reservoir developed in Majiagou Formation in Ordos Basin.Based on experimental analyses of cores,thin section examination,cathodoluminescence,electronic probe,carbon and oxygen isotope,and physical property,the characteristics and evolution of weathering crust reservoir in Fuxian area were studied.The result shows that gypsum and anhydrite mainly occurred as isolated nodules in Ma 5 penecontemporaneous dolomite in Fuxian area.These nodules were dissolved by meteoric water during Caledonian and experienced other diagenesis after buried,which forms the most significant reservoir spaces with diversiform filling degree and types.Sedimentary facies affects the porosity directly by controlling the size and quantity of nodules,and it could affect the reservoir permeability indirectly as the small quantity of nodules is not beneficial to the development of micro cracks among pores（Anhydrite would dilate when absorbing water and increase formation pressure,and the pressure would decrease after the nodules were dissolved,which then generated micro cracks）.Reservoir properties are principally determined by epidiagenesis.Gypsum was dissolved by meteoric water and pores formed during that period,and the pores located in the lower part of paleo-landform generally suffered totally filling of calcite.The effect of burial diagenesis on reservoirs in the study area is fairly weaker than that on the same reservoirs in the Central Gas Field of Ordos Basin.The formation mechanism of high-quality reservoirs was defined,and it is considered that favorable reservoirs are mainly located in overlapped areas between gypsum-bearing dolomite flat and paleohigh of karst geomorphology.Fine description about sedimentary facies and karst geomorphology should be the key for the further reservoir prediction.
出处
《岩性油气藏》
CSCD
北大核心
2016年第3期58-67,共10页
Lithologic Reservoirs
基金
国家重点基础研究发展计划(973)项目"中国早古生代海相碳酸盐岩层系大型油气田形成机理与分布规律"(编号:2012CB214802)
国家重大科技专项"海相碳酸盐岩层系优质储层分布与保存条件评价"(编号:2011ZX05005-002)及"岩性地层油气藏沉积体系
储层形成机理与分布研究"(编号:2011ZX05001-002)联合资助
关键词
膏质结核溶模孔
风化壳储层
成因演化
马家沟组
鄂尔多斯盆地
pores evolved from anhydrite and gypsum nodules
weathering crust reservoir
genesis evolution
Majiagou Formation
Ordos Basin
