致密砂岩储层微观孔隙结构特征——以鄂尔多斯盆地延长组长7储层为例

Characteristics of micro-pore structure of tight sandstone reservoir:A case study from Chang 7 reservoir of Yanchang Formation in Ordos Basin

运用物性分析、扫描电镜、铸体薄片及恒速压汞等技术,对致密砂岩储层进行了微观孔隙结构定量分析。研究结果表明:鄂尔多斯盆地长7油层组为典型的致密砂岩储层,渗透率小于0.3mD,孔隙类型以次生溶孔为主,平均孔隙半径为162μm,与渗透率无相关性;平均喉道半径为0.33μm,与渗透率具有很好的正相关性,是影响渗透率的主要因素;孔喉半径比大,平均为602,大孔隙被小喉道所控制,从而造成储层非均质性强、渗流能力差。致密砂岩储层的规模开发需采用先进的储层改造工艺,充分扩大喉道半径,降低孔喉比,提高储层渗流能力,这样才能取得更好的开发效果。

Based on reservoir properties, scanning electronic microscope, cast thin section and constant rate mercury penetration, this paper carried out quantitative analysis of micro-pore structure of tight sandstone reservoir. The result shows that Chang 7 reservoir in Ordos Basin is typical tight sandstone reservoir, the reservoir permeability is less than 0.3 roD, the secondary dissolved pore is the main pore type and average pore radius is 162 ~m, and there is no correlation with permeability; the average throat radius is 0.33 txm and has a good positive correlation with permeability, and it is the main influencing factor of permeability; the pore throat radius ratio is large and the average value is 602; the big pore is controlled by small throat, which causes reservoir advanced stimulation technology need to be used for large scale strong heterogeneity and poor permeability. So, the development of tight sandstone reservoir, and need to enlarge the throat radius and lower pore throat radius ratio and improve the permeability.