鄂尔多斯盆地镇原地区长8油层组超低渗储层孔隙结构特征

Pore structure characteristics of ultra-low permeability reservoirs of Chang 8 oil reservoir set in Zhenyuan area, Ordos Basin

孔隙结构特征作为油气勘探与开发中必不可少的重要基础资料,日益成为油气储层综合评价和油气藏精细描述中不可或缺的组成部分。根据岩石薄片、常规物性及高压压汞等分析结果,系统地研究了鄂尔多斯盆地镇原地区长8油层组超低渗储层的孔隙结构特征,并对其进行了分类评价。结果表明:镇原地区长8油层组岩石类型主要为富含长石和岩屑砂岩,总体属于低孔、超低渗储层,其喉道半径较小,产油能力较低,驱油效率不高,喉道分布的集中程度和均匀程度较差,粗细喉道分异性较强;砂岩孔隙结构可分为好、较好、中等、较差和差5类,其中中等和较差孔隙结构是镇原地区长8油层组中最为典型的孔隙结构类型。

As important basic data for petroleum exploration and development, the characteristics of pore structure increasingly became an indispensable part in the comprehensive evaluation and fine description of the oil and gas reservoirs. Based on the analysis of thin sections, routine physical properties and high-pressure mercury injection, this paper systematically studied the characteristics and comprehensive classification of the pore structure of the ultra-low permeability reservoirs of Chang 8 oil reservoir set in Zhenyuan area, Ordos Basin. The results show that the reservoir sandstones are characterized by feldspar and lithic-rich sandstone types, low-porosity and ultra-low permeability, micro- fine sizes of pore-throat radius, low capacity of oil production, not high efficiency of oil displacement, poor concentration and uniformity of pore-throat sizes, and strong differentiation between coarse-throats and fine-throats. The pore structure of reservoir sandstones can be divided into five types： good, slightly good, moderate, slightly poor and poor types. The moderate and slightly poor types are the most typical types of the pore structure.