Effect of Resins on Asphaltene Deposition and the Changes of Surface Properties at Different Pressures: A Microstructure Study

Abstract

Asphaltene deposition has hindered oil production from asphaltenic oil reservoirs through deposition in reservoir rock and surface facilities. This paper investigates the effect of resin on asphaltene deposition at different pressures. To investigate the asphaltene deposition in the presence of resins at reservoir temperature and different pressures, a pressure, volume, and temperature (PVT) visual cell was designed. A high-resolution microscope and image processing software were used to detect and determine the amount of deposited asphaltene as well as its size distribution at different conditions. Two types of Iranian crude oils with different potential of deposition (low and high) were used in this work. In the first stage, the amount of asphaltene deposition and the changes of surface properties were recognized through the depressurizing process with and without the presence of resins in the fluid. The wettability changes as a sign of surface properties were studied by contact angle measurement, and also for further investigation, the atomic force microscopy (AFM) technique was used. The results verify that the amount of asphaltene deposition increases when the pressure increases and the quantity of asphaltene deposition decreases as the resin/asphaltene ratio in these samples increases. At high ratios of resin/asphaltene, the asphaltene was found to be more stable. However, the results showed that, as the pressure increases, the stability of asphaltene decreases more than expected. The surface property changes indicate that, in the presence of resins, the surfaces become more water-wet and their roughness decreases.

Visual investigation and modeling of asphaltene precipitation and deposition during CO2 miscible injection into oil reservoirs

“…Aromatics are hydrocarbons which consist of one or more ring structures similar to benzene. The carbon atoms in aromatics are connected by double bonds [1][2][3]. Waxes contain linear paraffinic hydrocarbons with carbon chains of various lengths [4].…”

“…Asphaltenes are generally incompatible with light petroleum fractions leading to undesirable effects in many stages of the petroleum industry. Asphaltene molecules' tendency toward association and precipitation referred to their molecular structure [2,3,11]. However, it is not possible to verify it clearly due to the complex nature of asphaltene molecules.…”

“…It can change the wettability of the formation rock from water wet to oil wet which hinders the oil recovery efficiency [3,12]. To maintain the well flow and avoid pressure reduction due to the asphaltene deposition and plugging, several mechanical and chemical methods have been proposed.…”

“…These methods are mostly expensive and time-consuming. Therefore, the reduction of asphaltene precipitation is widely investigated in the literature [1][2][3][4][12][13][14].…”

Investigation of asphaltene deposition under dynamic flow conditions

“…Asphaltene composition, structure, and stability depend on its source, type of solvent used for oil extraction, pressure, and temperature (Soorghali et al 2014;Groenzin and Mullins 2000;Alboudwarej et al 2002;Akbarzadeh et al 2002). Asphaltenes as colloidal with various sizes or as individual molecules can be absorbed on solid surfaces by the virtue of their weak phenolic and carboxylic acid groups (Kokal et al 1995).…”