Effect of pore structure on electrical resistivity in carbonates
Effect of pore structure on electrical resistivity in carbonates
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DOI：
10.1306/06301010047
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发表时间：
2011-02
期刊：
影响因子：
3.5
通讯作者：
K. Verwer;G. Eberli;Ralf J. Weger
中科院分区：
文献类型：
--
作者：
K. Verwer;G. Eberli;Ralf J. Weger
电阻率测井已被证明是岩性判别、关联、孔隙度评估、碳氢化合物指示和含水饱和度计算的有力工具。碳酸盐岩发育多种孔隙类型，其尺寸和复杂性可以跨越几个数量级。电阻率和碳酸盐孔隙结构之间的联系已经被推断出来，尽管对这种关系还没有详细的了解。对来自五个不同地区和年龄的碳酸盐岩露头和钻孔的 71 个岩塞进行了电阻率特性测量，并使用薄片数字图像分析对孔隙结构进行了定量分析。分析表明，除孔隙率外，微孔隙率、孔隙网络复杂性、大孔孔径和孔隙绝对数量的综合影响对电荷的流动都有影响。孔隙小且孔隙网络复杂的样品胶结因子较低，而孔隙大且孔隙网络简单的样品胶结因子值较高。具有单独孔洞孔隙度的样品具有最高的胶结因子。结果表明：（1）在碳酸盐岩中，孔隙结构和孔隙绝对数量（以及孔隙连接）在控制电阻率方面似乎比孔喉大小更重要，正如之前的模拟研究所表明的那样； (2)电阻率高的样品才能具有高导磁率；大的简单孔隙有利于流体的流动，但较少的孔隙数量限制了电荷的流动； (3) 可以根据电阻率数据估算孔隙结构特征，并用于改进渗透率估算和细化含水饱和度的计算。
The electrical resistivity log has proven to be a powerful tool for lithology discrimination, correlation, porosity evaluation, hydrocarbon indication, and calculation of water saturation. Carbonate rocks develop a variety of pore types that can span several orders of magnitude in size and complexity. A link between the electrical resistivity and the carbonate pore structure has been inferred, although no detailed understanding of this relationship exists. Seventy-one plugs from outcrops and boreholes of carbonates from five different areas and ages were measured for electrical resistivity properties and quantitatively analyzed for pore structure using digital image analysis from thin sections. The analysis shows that in addition to porosity, the combined effect of microporosity, pore network complexity, pore size of the macropores, and absolute number of pores are all influential for the flow of electric charge. Samples with small pores and an intricate pore network have a low cementation factor, whereas samples with large pores and a simple pore network have high values for cementation factor. Samples with separate-vug porosity have the highest cementation factor. The results reveal that (1) in carbonate rocks, both pore structure and the absolute number of pores (and pore connections) seem more important in controlling the electrical resistivity, instead of the size of the pore throats, as suggested by previous modeling studies; (2) samples with high resistivity can have high permeability; large simple pores facilitate flow of fluid, but fewer numbers of pores limit the flow of electric charge; and (3) pore-structure characteristics can be estimated from electrical resistivity data and used to improve permeability estimates and refine calculations of water saturation.