恒速压汞技术定量评价低渗透砂岩孔喉结构差异性

Valuation on Difference of Pore Throat Structure of Low Permeability Sandstone by Constsp Mercury Penetration Technique

针对常规压汞不能准确确定储层孔隙与喉道的弊端，利用恒速压汞技术对鄂尔多斯盆地低渗透砂岩样品孔喉结构的差异性进行了定量评价。结果表明，渗透率越小的岩心，喉道分布越集中，随着渗透率的增大，大喉道分布逐渐增多，喉道分布范围也更加宽泛，主喉道半径随之增大，但较大喉道对低渗透砂岩储层的开采效果具有双重影响；渗透率小于0．5×10^-3μm2的岩心，主喉道半径小于1μm2，渗透率介于0．5×10^-3-1×10^-3μm2间的岩心，主喉道半径为1～2μm2孔道与渗透率大小之间基本没有相关性，低渗透砂岩孔喉结构的差异性主要体现在喉道上，喉道大小及分布影响最终开发效果。

In reference with the deficiency that the conventional mercury penetration method cannot determine accurately the pore and pore throat structure, constsp mercury penetration technique was used to quantitatively evaluate the pore structure difference in Ordos Basin. The study result shows that： the lower the core permeability is, the more concentrated the distribution of pore constriction is, and the larger pore constriction has dual effect on exploitation of low permeability of the sandy reservoir. With the rising core permeability, the distribution of big pore constriction increases, and the range of big pore constriction becomes more scattered and the radius of the main pore constriction is enlarged. The main pore constriction diameter of cores with permeability less than 0.5 ×10^-3μm2 is less than 1 μm. The main pore con- striction diameter of cores with permeability between 0.5 ×10^-3μm2 and 1 ×10^-3μm2 is 1 2 μm. The pores have little correlation with permeability, and difference of pore throat structures of low permeability sandstone is dependent upon pore constriction. The size and distribution of pore constriction will affect the final exploitation.