On the evaluation of the performance of asphaltene dispersants

Abstract

a b s t r a c tAsphaltene precipitation and subsequent deposition is a potential flow assurance problem for the oil industry nowadays. Moreover, because oil production is moving to more difficult production environments -e.g. deeper waters -or is focusing on extracting residual oil using enhanced oil recovery techniques, the significant changes of pressure, temperature and/or composition can aggravate the asphaltene deposition problems. One of the most common strategies to prevent or at least reduce asphaltene deposition is the utilization of chemical additives. However, there are still several unresolved challenges associated to the utilization of these chemicals: First, the experimental conditions and results obtained in the lab are not always consistent with the field observations. Also, in some cases these chemical additives seem to worsen the deposition problem in the field. Therefore, there is a clear need to revisit the commercial techniques that are used to test the performance of asphaltene inhibitors and to provide a better interpretation of the results obtained. In this work, a technique based on NIR spectroscopy is presented to evaluate the performance of three commercial asphaltene dispersants. The method presented in this work is faster and more reproducible compared to the available methods such as the Asphaltene Dispersion Test (ADT) and the Solid Detection System (SDS). Also, unlike the ADT test, our proposed method can evaluate the performance of the dispersants in a wide range of temperatures and compositions. The experimental evidence shows that the asphaltene dispersants neither shift the actual onset of asphaltene precipitation nor reduce the amount of asphaltene precipitated. We believe that some results that have been reported that suggest that asphaltene dispersants can actually shift the onset of asphaltene precipitation are an unfortunate combination of insufficient sensitivity of the commercial instruments used and the slowing down of the asphaltene aggregation process by the effect of the added dispersants. The chemical additive dosage, aging time and temperature effect on the asphaltene aggregation process are also discussed in this manuscript.With this work we aim to contribute to a better understanding of the variables that affect the performance of asphaltene dispersants, and the effect that these chemicals have on the complex multi-step mechanism of asphaltene precipitation and aggregation.

Characterizing Asphaltene Deposition in the Presence of Chemical Dispersants in Porous Media Micromodels

“…Without considering hydrodynamic effects on asphaltene aggregates, these chemical dispersants may worsen deposition and hasten flow assurance problems in the field. 28 Although commercially available alkyl-phenols have demonstrated various successes as asphaltene dispersants, it is not clear how these chemicals influence plugging and non-plugging asphaltene deposition processes. Therefore, it is important to study the performance of asphaltene dispersants under flowing conditions in porous media and integrate these studies with conventional dispersancy tests to form a multifaceted screening platform to better understand the influence of chemical additive injections for flow assurance.…”

SiO2 Biogenic Nanoparticles and Asphaltenes: Interactions and Their Consequences Investigated by QCR and GPC-ICP-HR-MS

“…The selective removal and fractionation of asphaltenes is required to produce homogeneous feedstock, making them easier to upgrade or use in other chemical industries 3 . For this purpose, the use of inhibitors that can prevent or delay asphaltene aggregation and deposition is a vast research field that goes from molecules, which can act as primary asphaltene dispersants or anti-flocculants [11][12][13][14][15][16][17] , to nanoparticles, which can adsorb asphaltenes and therefore inhibit their aggregation or deposition [18][19][20][21][22][23][24] . The use of nanoparticles can be advantageous over chemical inhibitors due to their easily tunable surface functionalities, high chemical and thermal stability in harsh conditions (high temperature, high salinity, high pressure, etc.…”

Asphaltene precipitation modeling in dead crude oils using scaling equations and non-scaling models: comparative study

“…Crude oils when suffering changes in their composition, due to variation of pressure and temperature conditions, cause asphaltenes to precipitate out and deposit (Gharbi et al 2017). This problematic situation offers severe challenges to operating companies in terms of preventing hydrocarbon production shutdowns and applying costly treatment methods (Melendez-Alvarez et al 2016). Therefore, this scenario makes it necessary for operators to predict the conditions and extent of asphaltene precipitation of a particular crude oil.…”