Assessment of the performance of asphaltene inhibitors using a multi-section packed bed column

Abstract

Asphaltene deposition is one of the major problems in the production, transportation, and processing of crude oils. The precipitated and subsequently deposited asphaltenes could cause the plugging of production tubing, significantly reducing oilfield productivity. Conventional asphaltene dispersants, particular types of asphaltene deposition inhibitors, are chemical supposedly used to improve the stability of oils, thereby preventing asphaltene deposition in the oilfield pipelines. The Asphaltene Dispersion Test (ADT) and the Solid Detection System (SDS) have been used to assess the performance of the asphaltene deposition inhibitors; however, these techniques have several limitations caused by the conceptual understanding of the asphaltene deposition mechanism and the instrument detection limit. Thus, the conventional asphaltene dispersants assessed by the ADT and the SDS might provide misleading results on the effectiveness of these chemicals to mitigate asphaltene deposition. The conventional asphaltene dispersants are developed based on their ability to reduce the size of asphaltene aggregates, but it is not necessarily true that the reduced sizes of asphaltene aggregates can mitigate asphaltene deposition. In this work, a multi-section packed bed deposition apparatus, which is applied not only to directly quantify the deposited asphaltenes but also to investigate the deposition profile, is developed. Then, the performance of three commercial asphaltene dispersants and three alkylphenols on the prevention of asphaltene deposition is assessed by the multi-section packed bed column. The experimental evidence shows that the dispersive performance of the inhibitors is not directly related to their ability to prevent asphaltene deposition. In some cases, the chemicals with the highest dispersive efficiency produce the largest amount of asphaltene deposition. Based on the novel understanding of the relationship between the dispersive performance of an inhibitor and its effect on the prevention of asphaltene deposition, a new generation of asphaltene inhibitors targeting the actual asphaltene deposition problems should be developed.