Bioremediation: Waxy Crude Oils Stranded on Low-Energy Shorelines

ABSTRACT The degradation of a waxy crude oil (Terra Nova) spilled on sand beach and salt marsh environments in Nova Scotia was monitored over a seven-month period. In the sand beach environment, low concentrations of stranded oil (0.3 percent by volume) were degraded in a matter of days by the indigenous biota, while higher concentrations (3 percent) were much more persistent (components as light as n–C11 remained after six months). In contrast, similar concentrations of oil were found to be extremely resistant to biodegradation in the salt marsh. Our results suggest that cleanup of waxy crude oils at low concentrations in sand beaches should be left to nature, since natural biodegradative processes occur rapidly. At higher oil concentrations, however, nutrient enrichment with agricultural fertilizers was found to be an effective countermeasure. While biodegradation of oil stranded in salt marsh environments is generally limited by oxygen availability, nutrient enrichment may be an effective countermeasure to treat low concentrations of waxy crude oil in salt marshes, provided the oil does not penetrate beneath the aerobic surface layer.

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Thermal Effect on Void Formation of Waxy Crude Oil Using Electrical Capacitance Tomography

Jurnal Teknologi ◽

10.11113/jt.v63.1509 ◽

2013 ◽

Vol 63 (1) ◽

Cited By ~ 1

Author(s):

Areeba Shafquet ◽

Idris Ismail ◽

Azuraien Jaafar

Keyword(s):

Crude Oil ◽

Void Fraction ◽

Crude Oils ◽

Electrical Capacitance Tomography ◽

Electrical Capacitance ◽

Waxy Crude Oil ◽

Sustainable Operations ◽

Waxy Crude ◽

Waxy Crude Oils ◽

Capacitance Tomography

Waxy crude oils are commonly found in many parts of the world and represent a huge amount of the global oil reserves. Precipitation of paraffin waxes during various phases creates many problems in the oil industry. Therefore, waxy crude oils create many flow assurance issues essentially linked to them and understanding of the effect of relevant factors and phenomena are of great practical importance. In process industries, the measurement of void fraction is considerably important for sustainable operations and the erroneous calculation could be the cause of many industrial accidents. The customary approach separates the two-phases first and then measures the mixture as individual components. These methods are not favorable as they may result in the disruption of incessant industrial processes. Due to these limitations, this study is aimed to analyze the gel formation behavior of a waxy crude oil under static and dynamic cooling using non-invasive/non-intrusive experimental technique; i.e. Electrical Capacitance Tomography (ECT). This paper describes a fabrication of dual-plane ECT sensor for testing of waxy crude oil at different temperature conditions. ECT images and raw data measurements have been obtained from the two planes are then normalised and then used for image reconstruction. The findings reported in this paper represent part of an ongoing investigation that may lead to develop a cross-correlation between the two planes. The outcome of the study could be used to fully understand the phenomenon of void fraction in waxy crude based on varying the temperature and also based on the design of ECT sensor.

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THE ELASTO-VISCOPLASTIC-TIME-DEPENDENT NATURE OF WAXY CRUDE OILS

Revista de Engenharia Térmica ◽

10.5380/reterm.v13i2.62088 ◽

2014 ◽

Vol 13 (2) ◽

pp. 16

Author(s):

B. A. Tarcha ◽

B. P. P. Forte ◽

E. J. Soares ◽

R. L. Thompson

Keyword(s):

Yield Stress ◽

Crude Oils ◽

Time Dependency ◽

Gelation Temperature ◽

Viscous Effects ◽

Waxy Crude Oil ◽

Waxy Crude ◽

Crucial Feature ◽

Waxy Crude Oils

Production in reservoirs located in deep and ultra-deep water that contain waxy crude oils faces a huge obstacle imposed by the low temperatures of the environment. When the waxy crude oil is subjected to a temperature below the Gelation Temperature, as in the case investigated in the present work, it exhibits a variety of non-Newtonian features: elasticity, plasticity, viscous effects, and time-dependency, which renders to this material a highly complex behavior. A crucial feature that is frequently ignored when the determination of the yield stress is being carried out is the timedependency nature of these materials. We demonstrate that this character has a significant impact on the measurement of the yield stress and, therefore, values obtained from a protocol that neglects time-dependency can be substantially different from a more careful procedure.

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LABORATORY STUDIES ON THE BEHAVIOR AND CLEANUP OF WAXY CRUDE OIL SPILLS

International Oil Spill Conference Proceedings ◽

10.7901/2169-3358-1989-1-105 ◽

1989 ◽

Vol 1989 (1) ◽

pp. 105-113 ◽

Cited By ~ 1

Author(s):

Ian Buist ◽

Stephen Potter ◽

Don Mackay ◽

Michael Charles

Keyword(s):

Crude Oil ◽

Oil Spills ◽

Sea Surface ◽

Laboratory Studies ◽

Waxy Crude Oil ◽

Waxy Crude ◽

Waxy Oil ◽

Waxy Crude Oils ◽

Conventional Oils ◽

Environmental Temperatures

ABSTRACT Small- and mid-scale laboratory tests were undertaken to investigate the behavior and cleanup of spills of waxy crude oils at sea. The results indicate that the behavior of such oils is very different from that of conventional oils. This difference is likely due primarily to the precipitation of waxes, asphaltenes, and other unknown resinous compounds as the oil evaporates or as environmental temperatures drop. Thus, the oil spreads, evaporates, and naturally disperses very slowly, or in the extreme, even gels into a semisolid mass. Waxy oil spills can be expected to survive on the sea surface considerably longer than an equivalent spill of conventional crude. The results of simple countermeasure tests suggest that waxy crude oil spills will be difficult to clean up, since they are very viscous, do not adhere well to oleophilic surfaces, and are extremely resistant to chemical dispersants.

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WEATHERING AND DISPERSION OF NAPHTHENIC, ASPHALTENIC, AND WAXY CRUDE OILS

International Oil Spill Conference Proceedings ◽

10.7901/2169-3358-1997-1-631 ◽

1997 ◽

Vol 1997 (1) ◽

pp. 631-636 ◽

Cited By ~ 6

Author(s):

Tove Strøm-Kristiansen ◽

Alun Lewis ◽

Per S. Daling ◽

Jorunn Nerbø Hokstad ◽

Ivar Singsaas

Keyword(s):

Crude Oil ◽

North Sea ◽

Crude Oils ◽

Diverse Range ◽

Waxy Crude ◽

The North ◽

Response Planning ◽

The North Sea ◽

Reliable Knowledge ◽

Waxy Crude Oils

ABSTRACT The chemical composition and physical properties of a crude oil determine the behavior of the oil and the way its properties will change when the oil is spilled at sea. Reliable knowledge of the oil's behavior will enable the most effective countermeasure techniques to be used in a spill situation. A diverse range of crude oils is coming into production in the North Sea. The weathering behavior and chemical dispersibility of three very different crude oils—Troll (naphthenic), Balder (asphaltenic), and Nome (waxy)—have recently been thoroughly investigated through bench- and meso-scale experiments. The naphthenic crude oil was also exposed to full-scale studies in the North Sea. This study shows that emulsion formation, the viscosity of emulsion, and the potential for dispersing emulsions by dispersant treatment may vary greatly for the different crude oils. It would be impossible to predict these differences with existing oil-weathering models based on fresh oil properties alone. Especially for abnormal (e.g., highly asphaltenic, waxy) crude oils, the weathering and dispersibility behavior can be revealed only by experimental work. The findings have important implications for effective oil spill response planning, particularly for estimating the most appropriate “window of opportunity” and for optimizing a dispersant application strategy for crude oils.

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Differential Scanning Calorimetry contribution to a better understanding of the aging of gelled waxy crude oils

Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles ◽

10.2516/ogst/2018095 ◽

2019 ◽

Vol 74 ◽

pp. 16 ◽

Cited By ~ 2

Author(s):

Isabelle Henaut ◽

Brigitte Betro ◽

Guillaume Vinay

Keyword(s):

Crude Oil ◽

Holding Time ◽

Waxy Crude Oil ◽

Scanning Calorimetry ◽

Calorimetric Analysis ◽

Waxy Crude ◽

The Past ◽

Fast Cooling ◽

Waxy Crude Oils ◽

Shear History

Below Wax Appearance Temperature (WAT), waxy crystals appear within the crude oil and make it viscous with yield stress and shear thinning properties. Particular attention has been paid during the past works on different parameters such as temperature, pressure, shear history, etc. Another important parameter is the holding time of the sample once it has gelled and left at rest under isothermal conditions. Actually, the network of waxy crystals is known to change with time. This phenomenon has been particularly observed in the case of deposit that is expected to harden. The set of rheological tests and calorimetric analysis that were performed on a real waxy crude oil confirm that a gel formed with waxy crystals may evolve with time and that the extent of this phenomenon depends on the thermo-mechanical past of the sample. Actually, a strengthening of the gel during holding time is observed in the case of fast cooling because the sample gets supersaturated. Aging takes place through isothermal crystallization that lasts a few minutes. The results have also shown that slowly cooled samples do not lead to any aging.

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Experimental Study of the Necessary Pressure to Start-Up the Flow of a Gelled Waxy Crude Oil

Volume 8: Polar and Arctic Sciences and Technology; Petroleum Technology ◽

10.1115/omae2017-62438 ◽

2017 ◽

Author(s):

Charlie Van Der Geest ◽

Vanessa C. Bizotto Guersoni ◽

Luiz Antônio Simões Salomão Junior ◽

Antonio C. Bannwart

Keyword(s):

Crude Oil ◽

Crystalline Structure ◽

Threshold Stress ◽

Rheological Behaviour ◽

Momentum Equation ◽

Rheological Parameter ◽

Waxy Crude Oil ◽

Waxy Crude ◽

Experimental Apparatus ◽

Waxy Crude Oils

The current study concerns a recurrent problem in the oil industry when dealing with waxy crude oils in offshore fields. When a waxy crude stays static in the seabed for any reason, it cools down below the wax appearance temperature (WAT). Hence, crystals of wax appear in the fluid. These wax crystals form a crystalline structure. The strength of a crystalline structure rises with time. What also rises with time is the minimum pressure necessary to restart the flow. When designing subsea structures, engineers assume that flow restart will occur when the pressure is sufficient to overcome a threshold stress. This threshold stress is related to what the literature calls apparent yield stress. Considerable evidence suggests, however, that a simplified momentum equation considering only this rheological parameter and the necessary pressure will provide an overestimated value. What this study aims to accomplish is a better understanding of the phenomenon involved in this process. To do so, we build an experimental apparatus that allows us to represent the condition of the temperature close to bottom of the sea, and a pressurization system that allows us to precisely control the inlet pressure. The apparatus is composed of a one-inch pipeline that is submerged in a water bath (5°C) and a nitrogen system with controlled valves to pressurize the inlet of the pipeline. Much discussion in the literature concerns the restart of a flow of gelled waxy crude. Many studies have suggested that the most important phenomena involved are the following aspects of the oil: its rheological behaviour, its compressibility, and its shrinkage. The current study contributes to the literature by demonstrating that the behaviour of a gelled waxy crude oil having a high percentage of wax that builds up a strong crystalline structure is impacted by rheological behaviour, time, and aging time. To be able to provide the industry a reliable prediction of the gelled waxy restart pressure, it is necessary for engineers to carry out a great deal of experimentation and improvement in the models. In this paper, we compare the experimental data with the prediction of a model consisting of a weakly compressible fluid with an elasto-viscoplastic thixotropic behaviour. The comparison advances our knowledge in the phenomena involved in restart of gelled crudes and, in fact, shows the model capable of approaching the results expected by the industry.

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Research Progress and Discussion of Waxy Crude Pour Point Depressants: A Mini Review

Recent Innovations in Chemical Engineering (Formerly Recent Patents on Chemical Engineering) ◽

10.2174/2405520413666200316162139 ◽

2020 ◽

Vol 13 (4) ◽

pp. 323-331

Author(s):

Zhengnan Sun ◽

Jing Zhang ◽

Guolin Jing ◽

Yang Liu ◽

Shuo Liu

Keyword(s):

Crude Oil ◽

Pour Point ◽

Three Dimensional ◽

Research Progress ◽

Crude Oils ◽

Waxy Crude ◽

Main Research ◽

Oil Exploitation ◽

Pour Point Depressants ◽

Waxy Crude Oils

The crude oils exploited in oilfields are mainly high-wax crude oils. Paraffins precipitate, crystallize, and form a three-dimensional network structure, when the temperature falls below the Wax Appearance Temperature (WAT), which decreases crude oil fluidity. This poses huge challenges to oil exploitation and transportation, as well as cost control. To date, the addition of chemical pour point depressants has been a convenient and economical method to improve low-temperature fluidity in crude oils. This article reviews the types of pour point depressants of crude oil and their performance mechanisms, and introduces the main research methods and progress made in the study of the performance mechanisms of pour point depressants in waxy crude oils. Finally, the development direction of pour point depressants is prospected.

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