鄂尔多斯盆地低渗透岩心水测渗透率和气测渗透率关系研究

Study on Relationship Between Water Measuring Permeability and Gas Measuring Permeability of Low Permeability Sandstone Cores in Ordos Basin

为研究鄂尔多斯盆地延长组低渗透储层的渗流特征并探讨其分类标准,对岩心气测渗透率(Kg)和水测渗透率(Kw)进行了测定分析。研究结果表明,Kg与Kw线性相关性良好,随Kg增大Kw也在增大,但不同Kg区间Kw增大幅度差异明显,总体表现为Kg<0.5×10^(-3)μm^2、0.5×10^(-3)μm^2<Kg<0.8×10^(-3)μm^2、Kg>0.8×10^(-3)μm^2三段式,Kw与Kg拟合直线段的斜率依次为0.0961、1.2993、0.2103,Kg/Kw平均值依次为19.27、3.97、3.22,(Kg-Kw)/Kg的变化范围依次为95.71%~92.12%、81.42%~66.08%、71.13%~65.54%。鉴于Kw随Kg的变化规律,建议取气测渗透率0.5×10^(-3)μm^2和0.8×10^(-3)μm^2分别作为致密储层、超低渗储层的上限,进一步精细划分低渗透储层。

The percolation features and classification criteria of the low permeability reservoir of Yanchang Formation in Ordos Basin are studied based on the data analysis of gas measuring permeability（ Kg） and water measuring permeability（ Kw） of the low permeability reservoir. The results show that there is a good linear correlation between Kgand Kw,Kgincreases with the increase of Kw,but the increase extent is different in different Kgintervals： the slopes of Kw-Kgfitting line are 19. 27,3. 97 and 3. 22 respectively,the average values of Kg/ Kware 19. 27,3. 97 and 3. 22 respectively,and the ranges of（ Kg-Kw） /Kgare 95. 71% 92. 12%,81. 42% 66. 08%and 71. 13% 65. 54% respectively when Kgis in three ranges of Kg〈 0. 5 × 10-3μm2,0. 5 × 10-3μm2〈 Kg〈 0. 8 × 10-3μm2and Kg〉 0. 8 × 10-3μm2. It is suggested to take Kg= 0. 5 × 10-3μm2and 0. 8 × 10-3μm2as the upper limit of tight oil reservoir and ultralow permeability reservoir separately. The further subdivision of the low permeability reservoir of Yanchang Formation in Ordos Basin can provide a scientific basis for the development of tight oil reservoir in Yanchang Formation of Ordos Basin.