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.

Asphaltene is the most associative component in crude oil and residual oil.Asphaltene can easily aggregate with each other through charge transfer,hydrogen bond and dipole interaction.Asphaltene may congregate and settle when external conditions or composition change,which poses a challenge to the petroleum industry.Asphaltene dispersants can effectively inhibit the agglomeration of asphaltene.In this paper,the research progress of asphaltene dispersants is reviewed from the aspects of asphaltene structure,dispersant types and dispersant mechanism,and the future development trend of asphaltene dispersants is analyzed.

This paper studies the stability of crude oil emulsion characterized by conductivity difference between upper and lower layers. According to the changes of conductivity in the upper and lower layers of crude oil emulsion system, combined with optical microscope observation, the methods and conditions to characterize the stability of crude oil emulsion can be studied by the difference of conductivity between the upper and lower layers. Research finds that when the crude oil system is demulsified and phase separated, the composition, morphology and conductivity of the upper and lower emulsions will be different.Therefore, the conductivity difference between the upper and lower emulsions can be used as the characterization parameter of emulsion stability. By measuring the conductivity and the difference values of the upper and lower layers of the system at different electrical test signal frequencies (0.1,1.0,10.0,100.0 kHz), it is found that the conductivity values and the difference values at high frequency are greater than those at low frequency, and the sensitivity is higher. In addition,when the conductivity difference is greater than 15%, the system is unstable. The experimental results show that the method is also suitable for emulsion system containing anionic surfactant.