Review of the Current Laboratory Methods To Select Asphaltene Inhibitors

Abstract

Asphaltene deposition is a long-standing problem that threatens the uninterrupted production of crude oil. Unlike other flow assurance problems, downhole asphaltene deposition is not well-understood partly as a result of the complexity and diversity of the asphaltene chemical structure. Continuous downhole asphaltene inhibitor injection is one of the preventive strategies used to mitigate the asphaltene deposition problem. Such chemicals that are injected in low dosage are screened in the laboratory before field implementation. Over the last 20 years, various asphaltene testing methods have been proposed for product selection and research and development. Still, the lack of lab to field correlation remains a challenge for the operators, service providers, and chemical companies. Therefore, the search for robust, rapid, and reproducible lab screening methods for asphaltene inhibitors is ongoing. This review summarizes lab evaluation techniques adopted by different researchers, their governing principles, and the pros and cons. It may serve as a guide for adopting appropriate strategies and pursuing further investigations on the lessons learned. The hope is that, with a more in-depth understanding of the current methodologies, a better workflow can be designed to select the proper asphaltene control products for field implementation.

Review of Asphaltenes in an Electric Field

“…One example of a possible inhibition technique is the addition of dispersants in order to change the net charge of the asphaltene aggregates, making them more dispersible in the oil mixture. 12,13 However, in the case of heavy oil with a high asphaltene content, this method is inefficient and costly. 14 To address this disadvantage, there is an increasing interest in removal of asphaltenes from crude oil by using electrodeposition.…”

“…The use of chemical inhibitors and manipulation of oil production conditions incorporate inhibition techniques, while the treatment methods comprise mechanical, thermal, chemical, biological, and electrical approaches. − Most of these techniques are extremely costly. One example of a possible inhibition technique is the addition of dispersants in order to change the net charge of the asphaltene aggregates, making them more dispersible in the oil mixture. , However, in the case of heavy oil with a high asphaltene content, this method is inefficient and costly . To address this disadvantage, there is an increasing interest in removal of asphaltenes from crude oil by using electrodeposition.…”

Novel Nanoparticle-Based Formulation to Mitigate Asphaltene Deposition

“…Chemical providers commonly use the asphaltene dispersant test (ADT) to screen asphaltene inhibitors based on their ability to disperse asphaltenes. − However, an inhibitor with a high dispersive performance does not necessarily reduce or prevent asphaltene deposition, and in some cases, they can even increase the deposits. − According to Vargas et al, a reduction in the aggregation rate can potentially increase the diffusion rate of primary particles to the wellbore surface, worsening the deposition problem . As a result, the industry is slowly shifting from evaluating asphaltene inhibitors using dispersion tests to deposition tests run at operational conditions much closer to the field …”

“…A review of the most commonly used techniques for asphaltene inhibitor selection is available elsewhere . Among the available deposition tests, the packed bed column deposition test has gained attention in recent years. ,− Kuang et al found that the dispersive performance of selected asphaltene dispersants and alkylphenols did not correlate with their ability to reduce or prevent asphaltene deposition in a packed bed column apparatus. In another study, an increase in the dosage of an asphaltene dispersant delayed the detection of deposition.…”

“…1 As a result, the industry is slowly shifting from evaluating asphaltene inhibitors using dispersion tests to deposition tests run at operational conditions much closer to the field. 17 A review of the most commonly used techniques for asphaltene inhibitor selection is available elsewhere. 17 Among the available deposition tests, the packed bed column deposition test has gained attention in recent years.…”