准层序与白云石有序度关系的研究——以鄂尔多斯盆地奥陶系马家沟组为例

摘要

Applying the sequence stratigraphy theory establishes the sequence stratus frame of parasequence controls dolomitization.This paper references the data records of geochemistry and thin section analysis to discuss the relationship of the carbon and oxygen isotopes,the order degree of dolomite,and the porosity and permeability in the Ordovician Majiagou Group parasequence.The research indicates that in the research area,the rocks located on the top of the parasequence and formatted later are affected by the later rainfall,exposure and dissolution,so the order degree of dolomite is higher than the dolomite located in the bottom and firstly formed.This relationship has very good corresponding relation with the porosity in the research area;the order degree of dolomite on the top of sequence is generally higher;and the porosity of corresponding dolomite is higher too.Parasequence strongly controls the order degree of dolomite,and the relationship existed generally in the region.%为了研究准层序与白云石有序度的对应关系,在分析鄂尔多斯盆地奥陶系马家沟组碳酸盐岩地球化学资料、镜下薄片资料的基础上,运用经典层序地层学准层序的理论来讨论鄂尔多斯盆地马家沟组准层序中碳氧同位素、白云石有序度与储层物性之间关系。研究表明,在研究区,位于准层序顶部后期形成的岩石受暴露、降雨以及溶解作用的影响,白云石有序度普遍高于底部先期形成的白云石,这种关系在研究区与孔隙度有非常好的对应关系。准层序与白云石有序度及储层物性的对应关系主要表现在,准层序的顶部白云石有序度比较高,储层物性比较好;准层序的底部白云石有序度比较低,物性比较差。