On the Development of an Enhanced Method to Predict Asphaltene Precipitation

Vargas, Francisco M.; Garcia-Bermudes, Miguel; Boggara, Mohan; Punnapala, Sameer; Abutaqiya, Mohammed I. L.; Mathew, Nevin Thunduvila; Prasad, Sudha; Khaleel, Aisha; Rashed, Mariam Hamad Al; Asafen, Hadel Yousef Al

doi:10.4043/25294-ms

Cited by 35 publications

(56 citation statements)

References 25 publications

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“…Flow assurance in the oil and gas industry has been focused on preventing asphaltene deposition. [1][2][3][4][5][6] Severe asphaltene problems often arise in the porous media near the wellbore region, where significant changes either in shear rates or pressure occur. As a result of these flow changes, nano-and micro-aggregates of the destabilized asphaltenes form in the crude oil.…”

Section: Introductionmentioning

confidence: 99%

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

Lin

Tavakkoli

et al. 2017

Energy Fuels

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Asphaltenes are components in crude oil known to deposit and interrupt flows in critical regions during oil production, such as the wellbore and transportation pipelines. Chemical dispersants are commonly used to disperse asphaltenes into smaller agglomerates or increase asphaltene stability in solution with the goal of preventing deposition. However, in many cases, these chemical dispersants fail in the field or even worsen the deposition problems in the wellbores. Further understanding of the mechanisms by which dispersants alter asphaltene deposition under dynamic flowing conditions are needed to better understand flow assurance problems. Here, we describe the use of porous media microfluidic devices to evaluate how chemical dispersants change asphaltene deposition. Four commercially used alkyl-phenol model chemical dispersants are tested with model oils flowing through porous media, and the resulting deposition kinetics are visualized at both the matrix-scale and the pore-scale. Interestingly, initial asphaltene deposition worsens in the presence of the tested dispersants, but the mechanism by which plugging and permeability reduction in the porous media varies. The velocity profiles near the deposit are analyzed to further investigate how shear forces affect asphaltene deposition. The deposition tendency is also related to the intermolecular interactions governing the asphaltene-dispersant systems. Furthermore, the model system is extended to a real case. The use of porous media microfluidic devices offers a unique

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Section: Introductionmentioning

confidence: 99%

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

Lin

Tavakkoli

et al. 2017

Energy Fuels

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“…In addition, a flash calculator, an algorithm developed by Prof. Vargas of Rice University [82], is incorporated into the program to calculate the partitioning of CO 2 , H 2 S, and H 2 O at a given temperatures and pressures. The flash calculator is based on the Peng Robinson equation of state and the most recent VLE thermodynamics in conjunction with mass balance relationships.…”

Section: Methodsmentioning

confidence: 99%

Scale Prediction and Control at Ultra HTHP

Kan

Dai

Zhang

et al. 2015

Day 1 Mon, April 13, 2015

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Production from deepwater environment often encounter ultra high temperature, pressure (ultra HTHP) and with more exotic fluid compositions. Most scale prediction programs were developed by semiempirically modeling the thermodynamic parameters using experimentally measured mineral solubilities and other chemical properties. However, the experimental data were limited at temperature, pressure, and ionic strength that were clearly below that typically encountered in deepwater production. Therefore, extending the existing thermodynamic models to HTHP applications is of questionable accuracy. Furthermore, the partitioning of H 2 O, CO 2 , and H 2 S in and out of the gas/oil phases during production can have a significant impact on scaling tendency. The authors have published papers on experimental solubility measurements and thermodynamic modeling to extend the solubility data to HTHP condition. The new thermodynamic parameters and a flash calculator that integrate the latest development of Equation of State (EOS) to model the partition of H 2 O, CO 2 , and H 2 S in hydrocarbon/aqueous phases at temperature and pressure have been incorporated into a scale prediction software that is specifically tailored for oil and gas production application.The objective of this paper is to validate the software's application range with a set of critically evaluated peer-reviewed mineral solubility data for general oilfield produced water and deepwater HTHP application. A total of 73 selected papers and more than 2,500 individual experimental data points were included in this evaluation. Our model has been shown to be applicable to greater than 95% of produced water compositions with SI prediction of better than Ϯ0.03 for halite, Ϯ0.05 for gypsum, Ϯ0.1 for calcite and anhydrite, and Ϯ0.2 for barite at temperature between 32 -500°F, and and pressure between 14.7 to 22,000 psia. The newly incorporated flash calculator is capable of predicting how CO 2 , H 2 S, and H 2 O partition in and out of the gas phase during production. The partitioning of CO 2 , H 2 S, and H 2 O between the hydrocarbon and aqueous phases has significantly changed the ion composition and pH and therefore, impacted the scaling tendency of the fluids at the production temperature and pressure. This is a particularly important issue for newer wells with high volumes of gas and low water cuts and for CO 2 flooding.

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“…To reconcile these results, one should look at the limitation of the techniques used. Once the asphaltenes start precipitating, the process leads to the formation of small particles in the order of 100-400 nm [31,38] that can further aggregate at later stages.…”

Section: Indirect Methodsmentioning

confidence: 99%

On the evaluation of the performance of asphaltene dispersants

Melendez-Alvarez

Garcia-Bermudes

Tavakkoli

et al. 2016

Fuel

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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.

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On the Development of an Enhanced Method to Predict Asphaltene Precipitation

Cited by 35 publications

References 25 publications

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

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

Scale Prediction and Control at Ultra HTHP

On the evaluation of the performance of asphaltene dispersants

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