Abstract

The physicochemical mechanism of the development of microstructural wettability in oil and gas reservoirs is experimentally justified. It is shown that this mechanism is associated with the formation of mosaic hydrophobic areas on the interstitial surface of the reservoir rocks. It was revealed that hydrophobic areas are formed due to the competition of adsorption processes between aromatic and aliphatic structures. For example, the relationships between the hydrophobization index (the ratio of the hydrophobic interstitial surface to the total pore surface) and adsorbed oil composition were identified by studying core samples of carbonate rocks from the Karachaganak oil and gas condensate field (Kazakhstan) and the Astrakhan gas condensate field (southwestern part of the pre-Caspian Basin, Russia). The spectral coefficients characterizing the relative contribution of certain hydrocarbons to the adsorbed oil composition were determined using infrared spectroscopy. The dependences of microstructural wettability on the spectral coefficients are experimentally established. It is shown that the composition of adsorbed oil has a multidirectional effect on microstructural wettability. The presence of aromatic, oxidized, and sulfurized structures increases the hydrophobization index, whereas the presence of aliphatic and branched structures leads to its reduction. The closest relationship was noted between the microstructural wettability and the spectral coefficient that characterizes the presence of aromatic structures in the adsorbed oil.

中文翻译：

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吸附油的成分组成对油气藏微观结构润湿性的影响

摘要

通过实验证明了油气藏中微结构润湿性发展的理化机理。结果表明，这种机理与储层岩石间隙表面上的镶嵌疏水区的形成有关。揭示了由于芳族和脂族结构之间的吸附过程的竞争而形成疏水区域。例如，通过研究来自卡拉察加纳克油气凝析气田（哈萨克斯坦）和阿斯特拉罕的碳酸盐岩的岩心样品，确定了疏水指数（疏水间隙表面与总孔隙表面之比）与吸附油组成之间的关系。凝析气田（俄罗斯里海前盆地西南部）。使用红外光谱法测定表征某些烃对吸附的油组合物的相对贡献的光谱系数。通过实验确定了微结构可湿性对光谱系数的依赖性。结果表明，吸附油的组成对微结构的润湿性具有多向影响。芳族，氧化和硫化结构的存在增加了疏水化指数，而脂族和支链结构的存在导致其降低。在微观结构润湿性和表征吸附油中芳香结构存在的光谱系数之间发现了最密切的关系。