西湖凹陷花港组低渗透砂岩储层孔隙结构

为明确西湖凹陷花港组低渗透砂岩储层孔隙结构与产能之间的关系,利用500余块铸体薄片资料和311块常规压汞分析测试资料对该地区孔隙结构特征进行了分析和评价。通过对微观孔隙结构特征参数与储层宏观物性参数相关性分析,优选出最大连通孔喉半径和平均连通孔喉半径作为孔隙结构分级参数,并运用数据构型方法确定出孔隙结构分级界限,建立了适合工区低渗气藏的新的分级标准。利用该标准及孔隙与喉道大小的组合特征,将花港组H3段砂岩储层的孔隙结构划分为6种类型:大-中孔粗喉型、中-小孔中喉型、中-小孔中细喉型、小孔细喉型、细-小孔微细喉型和细孔微喉型。根据孔隙结构分类结果划分了4种储层类型,产能级别分别对应高产、中产、低产和特低产,其中一类储层主要对应大-中孔粗喉型和中-小孔中喉型孔隙结构类型,孔隙度和渗透率均较高,对应产能为高产,是该地区最有利的储层。

STUDY ON THE PORE STRUCTURE OF LOW PERMEABILITY RESERVOIR OF THE HUAGANG FORMATION IN XIHU DEPRESSION AREA

In order to make clear the relationship between the porosity and the production capacity of the low permeability sandstone reservoir in Huagang Formation of the Xihu Depression, pore structures are studied. More than 500 cores data and 311 conventional mercury testing data are used. By the correlation analysis between the characteristic parameters of microscopic pore structure and macroscopic physical properties, choosing the maximum connected pore-throat radius and average connectivity of pore-throat radius as the favorable parameters for throat grading and using the method of data configuration, the paper determined the pore structure classification standards and established the new classification system that suitable for low permeability gas reservoir in this area. The pore structure of Huagang Formation H3 sandstone reservoir could be divided into six types including big-mid pore with coarse throat type, mid-small pore with mid throat type, mid-small pore with mid-fine throat type, small pore with fine throat type, small-fine pore with micro-fine throat type and fine pore with micro throat type. According to the classification of pore structure, the reservoir could be grouped into four types with the production capacity corresponding to high, middle, low, and ultra-low yield respectively. The first kind of reservoir corresponding to the big-mid pore with coarse throat type and the mid-small pore with mid throat type, of which porosity and permeability were higher as well as the capacity of yield, is the most favored reservoir.