Asphaltene Stability in Crude Oil during Production Process

Abstract

Asphaltene instability may take place in the reservoir leading to permeability damage and contributing to flow restriction issues. It may also occur in production strings and surface facilities causing conduit clogging. Any change in oil composition or pressure and temperature at any stage of production will destabilize crude oil producing asphaltene precipitation. In this study, the stability of target crude oil under the influence of a direct current (DC) is investigated. The amount of the asphaltene deposit and its electrical charge at various operating conditions are investigated. The method consists of applying a DC voltage between two metal electrodes immersed in the crude oil sample. The amounts of deposits accumulated on the surfaces of the electrodes are recorded during experiment time utilizing a miniature two load cells connected to the electrodes. Electric field strength up to 500V is applied. This study confirms that asphaltene colloids are electrically charged. The fact that deposits form on the anode surface proves that asphaltene particles possess a negative charge. The experiment shows that time and potential differences are sensitive parameters. At the first 24 hours, all the asphaltene in the crude oil were extracted. This phenomenon reflects either limited amount of asphaltene exists in the sample, or that the resin content plays a major role in asphaltene colloids charge switch.

Occurrence and Characterization of Paraffin Wax Formed in Developing Wells and Pipelines

“…However, based on crude oil's physicochemical properties (e.g., polarity and boiling-point temperature), it can be subdivided into 4 major fractions: saturates, aromatics, resins, and asphaltenes (SARA) [60]. Asphaltenes, which have the highest molecular weight, have a significant role in the deposition of organics during petroleum processing and production [61]. There are two mechanisms of asphaltene precipitation concerning the nature of asphaltenes in solutions (Figure 2a).…”

Dynamic asphaltene deposition control in pipe flow through the application of DC potential

“…Whereas some researchers claimed that asphaltene possess a predominantly positive charge in most non-aqueous dispersants (James and Richard 1963;Lichaa and Herrera 1975;Leon et al 2000;Gonzalez et al 2003), some reported their net negative surface charges based on electro-deposition experiments with neat crude oil samples (Idem and Ibrahim 2002;Nasser and Belhaj 2010;Belhaj and Khalifeh 2013). Also noteworthy is the work of Leontaritis and Mansoori (1987) who showed that the net negative charge on asphaltene colloidal surface is the prime cause of deposition on metal pipes due to the potential difference across them.…”

A theoretically modified PC-SAFT equation of state for predicting asphaltene onset pressures at low temperatures

“…Also, in onshore assets the costs by each can be very high. Belhaj et al [241] published that "several major onshore fields in Abu Dhabi are challenged with asphaltene deposition in their producing wells. One asphaltene clean-up operation using organic solvents and coiled tubing unit costs US $200,000.…”