四川盆地磨溪构造嘉二段孔隙型碳酸盐岩储层的评价

嘉二²B层的粉晶云岩储层和嘉二¹亚段的泥晶-泥粉晶云岩储层是川中磨溪构造嘉二段气藏的主力产层,物性较好,且平面上分布稳定,但测试成果显示,其产能相差甚远。对储层岩石的镜下特征、毛细管压力特征以及孔隙度与渗透率关系等方面进行的分析表明,这两套储层的微观孔喉结构差异较大,嘉二¹亚段储层尽管孔隙度较高,但由于喉道细,连通性差,流体在其中的渗流能力因此明显下降。笔者采用主成分分析法,从原始变量的相关矩阵出发,通过研究其内部结构,找出起主导作用的新变量,针对不同孔喉结构的储层分别建立不同的分类评价标准,从而更客观地反映储层对流体产出的贡献值。

Evaluation of porous carbonate reservoir of Jia 2 Member in Moxi Structure of Sichuan Basin

The crystal powder dolomite reservoir of Layer Jia2² B and micrite-crystal powder dolomite reservoir of Sub-member Jia2¹ are the principal fluid producing formation in Moxi Structure of the Central Sichuan Basin and have the favorable physical property and stable distribution in plane. The tested results show that the two reservoirs have the obviously different productivity. The detailed analysis on endoscopic features, capillary pressure features and porosity-permeability relations of reservoir rocks indicated that the microscopic pore-throat structures were greatly different in the two reservoirs. Although the Sub-member Jia2¹ has the favorable porosity, the fluid permeability is still not ideal because of its thin throat and poor connectivity. By adopting the principle component analysis method and the matrix of original variables, the inner structures of the reservoirs were investigated to locate the new leading variables. Various classification and evaluation standards for reservoirs with different pore-throat structure were established and used to objectively describe the contribution of reservoir to fluid deliverability.