Analysis of Wellbore Blockage Causes and Study on the Asphaltene Properties in Blockage Materials

To address the challenge of wellbore blockage during the development of a certain oilfield, Y3 crude oil was taken as the research object. Laboratory experiments were conducted to analyze the composition of the crude oil and the main components of wellbore blockage materials.Toluene extraction was performed on formation blockage materials collected from the oilfield, and XRD was used to analyze the composition of toluene⁃insoluble substances. The soluble fraction was separated into four components, with a focus on studying the composition and properties of asphaltenes in the soluble fraction and Y3 oil samples. Through asphaltene adsorption experiments, oil⁃water interfacial tension, underwater contact angle, etc., were measured to explore the effects of asphaltene polarity and aromaticity on interfacial properties. The experimental results show that the main minerals of the formation blockage of the wellbore are quartz, feldspar, calcite, etc. Compared with the asphaltene in Y3 crude oil, the asphaltene in the blockage has higher molecular weight, heteroatomic mass fraction and aryl carbon ratiowith minimal wax content in blockage materials. The main cause of wellbore blockage was the adsorption of asphaltenes on sandstone. The heteroatom mass fraction and polarity of asphaltenes had significant effects on adsorption capacity and interfacial tension.