孔喉半径对松辽盆地南部青一段特低-超低渗透储层质量的控制作用

Control Effect of Pore Throat Radius on Quality of Extra-Low and Ultra-Low Permeability Reservoir in Member 1 of Qingshankou Formation,Southern Songliao Basin

针对青山口组一段特低-超低渗储层开发时,仍然存在储层认识程度低的问题.其中,明确特低-超低渗储层物性、含油性及流动性的主控因素是亟待解决的重要问题.利用常规压汞、核磁共振、孔渗测定、粒度分析和X衍射等实验方法,对松辽盆地南部青山口组一段特低-超低渗储层特征参数进行定量表征.结果表明:松辽盆地南部青山口组一段特低-超低渗透储层平均孔喉半径主要分布于0.3～1.7μm之间.大于1.5μm的孔喉半径对应常规低渗透储层,以细粒长石岩屑砂岩为主;0.5～1.5μm孔喉半径对应特低渗透储层,以极细粒长石岩屑砂岩和粗粉砂岩为主,可动流体饱和度大于65%;0.1～0.5μm孔喉半径对应超低渗透储层,以粗-细粉砂岩为主,可动流体饱和度介于50%～60%.孔喉半径决定了储层物性和流体饱和度特征,并在宏观上受控于沉积相带,应作为特低-超低渗储层评价的重要参数.

Among the uncertainties in development of extra low and ultra-low permeability reservoirs in the Qingshankou Formation,it is clear that the main controlling factors of the porosity, permeability, oil saturation and mobility are important issues to be solved. The characteristic parameters of extra-low and ultra-low permeability reservoirs in the Qingshankou Formation of the southern Songliao basin were quantitatively characterized by mercury intrusion, nuclear magnetic resonance, porepermeability measurement,grain size analysis and X ray diffraction test in this study. The results show that the pore throat size of the ultra-low permeability reservoir in southern Songliao basin is mainly distributed between 0.3 μm and 1.7 μm,which is the main controlling factor of reservoir property and fluidity. The pore throat radius of more than 1.5 μm corresponds to the conventional low permeability reservoir, and the rock type of the reservoir is mainly composed of fine feldspar lithic sandstone. 0.5-1.5 μm pore throat corresponds to ultra-low permeability reservoir. The rock type is mainly composed of very fine feldspathie lithie sandstone and coarse siltstone. The moveable fluid saturation is more than 65% 0.1-0.5μm pore throat corresponds to uhra-low permeability reservoir, and the rock type is mainly coarse-fine siltstone, moveable fluid saturation between 50 %- 60%. It is concluded that pore throat radius which has heen controlled by the sedimentary facies determines the characteristics of reservoir physical properties and fluid saturation, and it should be used as a significant parameter of reservoir evaluation.