埋藏环境白云石结构类型

Classification of Texture in Burial Dolomite

近年来我国在白云岩储层油气勘探方面取得了重大进展,这些白云岩储层绝大多数为埋藏阶段形成的白云岩,同时大量研究也证实地层中大部分白云岩形成于埋藏环境。国际学术界对埋藏环境白云石的成因结构分类比较细致,但在我国这方面的研究还不够深入,因此本文借助国际上对埋藏环境白云石成因结构的分类方法,并结合中国白云岩研究的实际情况尝试提出埋藏环境白云石结构分类方案。该方案首先以白云石在岩石中的产状分为基质白云石和胶结白云石两大类,再以晶粒大小、晶型、晶面特征、接触关系为分类依据,将埋藏环境白云石分为六种结构类型。

In recent years,a great progress in hydrocarbon exploration has been achieved in dolomite reservoirs in which several large scale hydrocarbon pools were discovered in China. In view of which most of these dolomite reservoirs were formed during burial period,together with the high abundance of burial dolostones in stratigraphic columns,this paper aims to focus on classification of genetic texture in burial dolomite without consideration for relatively simple textures of primary or penecontemporaneous micritic dolomite. In international academic community,the classification of genetic texture of burial dolomite were well documented,but were less paid attentions in Chinese academic circle. In order to improve further study in this field,it is necessary to distinguish the different textures of dolomite formed in buried period,so that to understand the different characters of dolomization liquid. We here introduce a modified classification scheme for genetic texture of burial dolomite with references of classification about this field in international academe and combining the actual situation of dolomite researching in China. First of all,on the basis of dolomite occurrence,the dolomite texture is divided into two types：matrix dolomite and cement dolomite,Then according as crystal size,crystal shape,crystal surface and contact relation,burial dolomite is classified into six types,in which four are matrix：1） finely crystalline,planar-e（ s） ,floating dolomite; 2） finely crystalline,planar-e（ s） dolomite; 3） finely-coarsely crystalline,nonplanar-a dolomite matrix; 4） coarsely crystalline,nonplanar saddle dolomite matrix,and the remanent two are cement：1） finely-medium crystalline,planar-e（ s） dolomite cement; 2） coarsely crystalline,nonplanar saddle dolomite cement. These texture classification provides a basis on which the dolomites formed in different diagenetic stages can be sorted out properly in the context of physical-chemical conditions of dolomitisiting fluids from which they formed,which provides effective approach of dolomite studying.