[en] The oil spill prevention and response research program of the U.S. Minerals Management Service was described including its goals and objectives, some recently funded projects, and future research directions. As it is now the trend in most research organizations, a large part of the program is carried out in cooperation with other major research centers to leverage funds and to maximize study results. For example, joint research with Environment Canada focuses on the physical and chemical properties of dispersants, remote sensing and mapping oil slicks and shoreline cleanup strategies. Similarly, cooperative projects are underway with the National Institute of Standards and Technology in assessing the capabilities of in-situ burning as an oil spill response tool. Research capabilities of OHMSETT - The National Oil Spill Response Test Facility were also reviewed. A series of tables listed titles of research projects completed during 1995-1996. 5 tabs.,

[en] The stability of water-in-oil emulsions were studied by examining the asphaltene and resin content of oils. The visco-elastic properties of 82 oils from Environment Canada's Emergencies Science Division were also examined to determine which factors are responsible for the stability regimes. The stability of emulsions were grouped into three categories: (1) stable, (2) unstable, and (3) meso-stable. It was shown that there is a range of compositions and viscosities in which each type of water-in-oil state exists. It was also shown that the viscosity of a stable emulsion at a shear rate of one reciprocal second is about three times greater than that of the starting oil. An unstable emulsion typically had a viscosity of 20 times greater than that of the starting oil. A stable emulsion had pronounced elasticity, but an unstable emulsion did not. A meso-stable emulsion had properties between stable and unstable, but broke down after a few days of standing. It was concluded that the formation of both stable and meso-stable emulsions is due to the combination of surface-active forces from resins and asphaltenes from viscous forces. Only a small difference was detected between stable and meso-stable emulsions. Stable emulsions were found to have more asphaltenes and less resins and a narrow viscosity window. Instability results when the oil has either a high viscosity or a very low viscosity and when the resins and asphaltenes are less than about 3 per cent. In highly viscous oils, the migration of asphaltenes and resins is too low to permit droplet stabilization, therefore the formation of stable or meso-stable emulsions does not occur in highly viscous oils. 18 refs., 8 tabs., 8 figs

[en] The durability of a fire resistant boom and its ability to contain oil during an in situ burn without creating any environmental damage as a result of the burning crude was evaluated. The screening test included four stages: (1) the pre-burn wave stress stage, where the test boom was flexed under tension in waves to simulate deployment of the boom and transit to the spill site, (2) the burn in wave stage, where the test boom was exposed to waves and repeated on hourly cycles of a propane gas fire to simulate oil burning operations, (3) the post-burn wave stress stage, where the test boom was again flexed under tension in waves to simulate retrieval of the boom, and (4) the oil-containment stage, where the ability of the boom to contain thick pools of hot oil was assessed. Three recommendations were made after the test program: (1) increase the heat generated by fire, (2) increase the tension on the boom, and (4) improve the data acquisition system. 10 refs., 10 tabs., 13 figs

[en] Experiments were conducted to study the role of asphaltenes in water-in-oil emulsions. Asphaltenes are the agents that act like surfactants and are responsible for the formation and stability of these emulsions. Experiments were conducted on an emulsion that had been standing for three months, and on a salt water-oil emulsion. A series of tests were performed to study how asphaltenes would migrate in the absence of a strong gravity effect. All the experiments showed that asphaltenes migrate to the oil-water interface from the oil. This explains why an emulsion which sits for a long time can become more viscous and more stable as time progresses. Future work will determine whether resins will behave in the same manner. 36 refs., 2 tabs

[en] Six crude oils were tested to determine the suitability of in situ burning as a response to oil spills. In situ burning can remove large quantities of oil from the water surface and is an effective countermeasure during a spill cleanup, but evaporation of an oil's light ends and the formation of water-in-oil emulsions can result in an oil becoming not ignitable. More powerful igniters are always being developed and chemical surfactants are being used to extend the window-of-opportunity for in situ burning. The Catalog of Crude Oil and Oil Products Properties is a catalogue which lists the physical and chemical data of over 380 different types of oils, including some information on dispersibility. This study was intended to provide additional data on in situ burning that should be considered when developing oil spill response plans. The following parameters with respect to in situ burning were tested: (1) the limits to ignition using gelled-gasoline igniters imposed by evaporation and emulsion-formation, (2) the ability of commercially-available emulsion breakers and alternative fuel igniters to extend the window-of-opportunity for ignition of stable emulsions, (3) the effects of wave action on the combustion of emulsion slicks, and (4) the possibility of the residues sinking after efficient burns of thick slicks of the crude oils. The study showed that in situ burning is not a suitable response option for all oils. 9 refs., 4 tabs

[en] Energy onset of water-in-oil formation was studied. Four clearly-defined states of water-in-oil have been characterized by a number of measurements and by their visual appearance on the day of formation and a week later. Results showed that the energy threshold for the onset of the two states is very low, usually between 300 and 1500 ergs. Bunker C oil, which forms an entrained water state, exhibited no increase in stability with increasing energy input after the initial formation point. Prudhoe Bay oil formed a meso-stable emulsion. It also showed a similar tendency, i.e. no increase in stability after the energy onset, although energy onset occurs at a much higher level of about 25,000 ergs. Arabian Light and Sockeye oils that form stable emulsions exhibited increased stability with increasing energy, the rate of increase being gradual. 16 refs., 6 figs

[en] A study was conducted to determine the stability of water-in-oil emulsions in the OHMSETT tank facility. The results were then compared with previous laboratory studies which suggested that the stability of emulsions can be grouped into four categories, stable, unstable, meso-stable and entrained. It has been determined that entrained emulsions can retain oil by viscous forces long enough for interfacial agents, resins and asphaltenes to stabilize the droplets. This paper also described the difference in viscosity between the 4 categories of emulsion stability. The OHMSETT tests were conducted in two series of one week each. The first series of tests were conducted in July and involved 12 experiments on 2 different types of oils which were placed at varying thicknesses on the water. The second set of tests were conducted in November and involved 12 experiments on 6 oils. The rheological properties of the oils were measured and compared to the same oils undergoing emulsification in the laboratory. The oils and water-in-oil states produced were found to have analogous properties between the laboratory and the first set of tests at the OHMSETT facility. All the oils tested produced entrained water-in-oil states in both the laboratory and the test tank. The energy in the two test conditions was found to be similar, with the OHMSETT emulsions similar to one produced in the laboratory at high energies. The second series of tests at OHMSETT did not result in the expected water in-oil- states. This unexpected result was most likely due to the residual surfactant from an earlier dispersant experiment. The study showed that the conditions for emulsion formation are analogous in the OHMSETT tank and in the laboratory tests. The level of energy is considered to be the major variant. It was concluded that the energy levels between the laboratory mixing experiments and the OHMSETT is similar. It was shown that surfactants left over from dispersant testing inhibited the formation of water-in-oil states. The confirmation of one emulsion formed at sea from the ERIKA spill, showed some evidence that this is also analogous to conditions at sea. 4 refs., 7 tabs., 4 figs

[en] The energy and work onset of water-in-oil state formation was determined based on two series of experiments which examined the kinetics of the formation or binding energy in emulsions. Work was defined as the energy expended over time. The first experiment measured the work and energy threshold, and the second measured the properties and stability of emulsions. The energy threshold measurements were performed by changing the rotational rate and energy of the apparatus used to make the emulsions. Work was varied by using different time periods of agitation at constant energy rotations. Visual observations and rheological measurements were used to analyse the emulsions. It was determined that turbulent energy was the most important form of energy related to emulsion formation. Since turbulent energy could not be measured in the given apparatus, the total energy was used as an estimate of the energy available for emulsion formation. It was concluded that minimum energy threshold is needed for most emulsion formations, but only work correlates with the value of the stability. This finding is of significance for the formation of emulsions at sea, where a given level corresponding to turbulent energy at sea would require some time before a known water-in-oil state would occur. This paper also described the progression in the formation of emulsions. 5 refs., 3 tabs., 7 figs

[en] Environment Canada's Laser Environmental Airborne Fluorosensor (LEAF) system was tested in a series of overflights over naturally occurring oil seeps off Santa Barbara, California. The objective was to test the system's ability to detect oil in actual marine environments and to distinguish petroleum oil from biogenic oils released by kelp beds in and around these naturally occurring oil seep areas. High resolution colour reconnaissance camera images and down-looking video images were collected concurrently with the fluorescence data for documentation purposes. Results of the experiment were analyzed in detail. They confirmed the system's ability to produce geo-referenced oil contamination location maps in real-time. The fluorescence data obtained during overflights was most similar to typical crude oil, i. e. the system successfully distinguished between biogenic oil and typical petroleum oil. 9 refs., 1 tab., 3 figs

[en] The stability of water-in-oil emulsions of more than 100 oils, including a sample from the ERIKA spill, were determined. An emulsion must be characterized as stable, meso-stable or unstable before its unique properties can be characterized. The samples from this study were analysed after one year of storage to study the change in properties over time. The samples were made in a rotary agitator and then their rheometric, viscosity and water content characteristics were studied. Observations were made on the appearance of the emulsions and were used to classify them. A summary of the property changes for the different types of emulsions over three time periods was tabulated. It was confirmed that water can occur in oil as entrained water where large droplets are suspended temporarily by viscous forces. Results also showed that the viscosity of a stable emulsion at a shear rate of one reciprocal second is about three times greater than that of the starting oil, and is highly elastic. An unstable emulsion generally has a viscosity of up to 20 time greater than that of the starting oil and is not elastic. A meso-stable emulsion has properties between stable and unstable and breaks down within a few days. It was concluded that asphaltene and resin content plus the viscosity of the starting oil are the most important property factors in determining what type of water-in-oil state is produced. 4 refs., 6 tabs