微生物白云岩储集层特征、成因和分布——以四川盆地震旦系灯影组四段为例

摘要

Based on the drilling cores and slice observations,single well data and geochemical analysis,this paper analyzed features,origin and distribution of the 4th Member reservoirs of Sinian Dengying Formation (Z2dn4) in the Sichuan Basin.It is demonstrated that the main reservoir is a set of microbial dolomites.The discovery of spherical dolomite has revealed that the dolomitization was related to the microbial action,belonging to the early protodolomite of low-temperature precipitation;the primary matrix pores and the penecontemporaneous eroded pores constituted the subject of the reservoir space,which was not due to the interlayer karst process related to the Tongwan Movement and burial-hydrothermal dissolutional process.The microbial mound-shoal complex and penecontemporaneous dissolution mainly control the development and distribution of the scaled reservoirs in Z2dn4.The microbial dolomite reservoir surrounding the intracratonic rift had a large thickness,good continuity and high quality,and was an important target of the survey.%基于岩心和薄片观察、单井资料及地球化学分析结果,剖析四川盆地震旦系灯影组四段(简称灯四段)储集层特征、成因和分布.微生物白云岩为灯四段主力储集层,球形白云石的发现揭示白云石化与微生物作用有关,属早期低温沉淀的原白云石;原生基质孔和准同生溶蚀孔洞构成储集空间的主体,而不是前人所认为的与桐湾运动相关的层间岩溶作用及埋藏-热液溶蚀作用成因.微生物丘滩复合体和准同生洛蚀作用是灯四段储集层规模发育和分布的主控因素.台内裂陷周缘的微生物白云岩储集层厚度大、连续性好、品质优,是重要的勘探对象.