原油沥青质在油藏岩石表面的吸附特性

Adsorption characteristics of crude oil asphaltenes on the surfaces of reservoir rocks.

选用两种原油沥青质样品，对沥青质在岩石孔隙表面的吸附及吸附所引起的润湿性变化进行了实验研究。对润湿性的测定结果表明，油藏岩石润湿性改变的程度主要取决于沥青质的来源和地层水的离子组成，同时也与离子浓度和岩样的束缚水饱和度有关。通过使用分光光度法测定沥青质在砂岩上的吸附量，初步建立了润湿指数（ＷＲ）与沥青质吸附量（ａ）之间的定量关系。对于某一给定的原油沥青质，ＷＲ值随ａ值增加而趋于降低。

The adsorption of asphaltenes on the surfaces of reservoir rocks and the wettability alteration caused by adsorption are studied experimentally using two asphaltene samples prepared from crude oils. The results of wettability determination show that the extent of wettability alteration is mainly dependent on the types of asphaltene and the ion constituent of formation water, and is also related to the ion concentrations and irreducible water saturation of core samples. The amount of asphaltenes adsorbed on sandstone samples is obtained by spectrophotometric measurements, which allows to establish the correlations of wettability indices ( W R) and the amount of asphaltenes adsorbed ( a ) preliminarily. The values of W R decrease with the increase in the values of a for a given crude oil asphaltene.