陕北顺宁油田长2^1低渗透砂岩储层综合分类评价

SYNTHETICAL CLASSIFICATION ADN EVALUATION OF CHANG 2^1 LOW PERMEABILITY SANDSTONE RESERVOIRS IN SHUNNING OIL FIELD, NORTH OF SHAANXI PROVINCE

根据实验分析,结合录井、试采等成果,对顺宁油田长21低渗透砂岩储层特征等进行分析研究和综合评价,认为:长21储层孔渗分布特征属于以中孔特低渗-低渗型为主的储层,微观结构以中-大孔隙、细到中-粗喉道组合为主,孔喉结构特征对储层渗透性有决定性影响,储层渗流能力主要由较大的孔喉提供;长21储层可以划分为Ⅰ,Ⅱ,Ⅲ,Ⅳ4大类型及相应的A,B亚类;综合评价长21储层属于以Ⅰ,Ⅱ两种类型为主要构成的低渗-特低渗透储层,其中A亚类储层的孔喉结构优于B亚类,渗流能力也将好于B亚类,然而分流河道及其旋回沉积的不同部位控制了储层类型的发育状况。

Based on experimental analysis,combined with feedbacks of well logging and test production,analytical study and overall evaluation of Chang2^1 low permeability sandstone is carried out. The porosity and permeability distributional characteristics of Chang 2^1 reservoirs show that the reservoir beds are mainly composed of middle-porosity and special low permeability type. Its microscopic textures are mainly of assemblage of mid-macropore,fine to mid-coarse throat and the pore throat feature has crucial influence on reservoir is permeability,and the filtration capability of reservoir provided by major pore throat. Chang 2^1 reservoir beds may be divided into four major type of Ⅰ , Ⅱ , Ⅲ , Ⅳ and into two subtypes of A and B. Chang 2^1 reservoir beds belong to low-special low permeability type mainly composed of type Ⅰ and Ⅱ two. Of the subtypes,pore-throat microstructure of subtype A is better than those of subtype B. It is found that the different parts of distributary channel and cyelotheric sedimentation controls the development regime of reservoir bed types.