Subsea Release of Oil & Gas – A Downscaled Laboratory Study Focused on Initial Droplet Formation and the Effect of Dispersant Injection

2014 ◽  
Vol 2014 (1) ◽  
pp. 283-298
Author(s):  
Per Johan Brandvik ◽  
Øistein Johansen ◽  
Umer Farooq
Keyword(s):  
Droplet Size ◽  
Sea Water ◽  
Droplet Formation ◽  
Size Distributions ◽  
Oil Droplets ◽  
Substantial Impact ◽  
Dispersed Oil ◽  
Laboratory Facility ◽  
Injection Techniques ◽  
Droplet Sizes

ABSTRACT This article describes the SINTEF Tower Basin (located in Trondheim, Norway) and its use for examining droplet formation and the effectiveness of dispersant injection. The Tower Basin is 6 m high and 3 m in diameter, containing 42 m3 of natural sea water. Oil is injected from the base of the basin and oil droplets are monitored by laser diffraction and in-situ camera techniques. Size distributions of oil droplets formed in deep water oil & gas blowouts have a substantial impact on the fate of the oil in the environment. However, very limited data on droplet size distributions from subsurface releases exist. The objective of this study has been to establish a laboratory facility to examine droplet size versus release conditions (flow rates and nozzle diameters), oil properties and injection of dispersants (injection techniques and dispersant types). Changes in the size of oil droplets that result from injection of dispersant are used to assess the effectiveness of the dispersant application (dosage and injection method). This comprehensive dataset is used to develop and calibrate existing algorithms to predict droplet sizes from subsurface releases, and the effect of dispersant treatment. The improved algorithms are implemented in current operational models where they are used to describe subsurface use of dispersant and fate of the dispersed oil in the water column.

OIL SPILL CLEANUP WITH DISPERSANTS: A BOOMED OIL SPILL EXPERIMENT

1981 ◽  
Vol 1981 (1) ◽  
pp. 263-268
Author(s):  
Joseph Buckley ◽  
David Green ◽  
Blair Humphrey
Keyword(s):  
Water Column ◽  
Oil Spill ◽  
Oil Spills ◽  
Sea Water ◽  
Visual Observation ◽  
Oil Droplets ◽  
Oil Boom ◽  
Dispersed Oil ◽  
Vertical Density ◽  
Oil Spill Cleanup

ABSTRACT Three experimental oil spills of 200, 400, and 200 litres (l) were conducted in October, 1978, in a semiprotected coastal area on Canada's west coast. The surface slicks were restrained with a Bennett inshore oil boom. The spilled oil was chemically dispersed using Corexit 9527, applied as a 10-percent solution in sea water and sprayed from a boat. The dispersed oil was monitored fluorometrically for some hours. Surface and dispersed oil were sampled for chemical analysis. The highest recorded concentration of dispersed oil was 1 part per million (ppm). After a short time (30 minutes), concentrations around 0.05 ppm were normal, decreasing to background within 5 hours. The concentrations were low compared to those expected for complete dispersion which, as visual observation confirmed, was not achieved. The dispersed oil did not mix deeper into the water column with the passage of time, in contrast to predicted behaviour and in spite of the lack of a significant vertical density gradient in the sea water. This was attributed to the buoyancy of the dispersed oil droplets and the limited vertical turbulence in the coastal locale of the experiment. The integrated quantity of oil in the water column decreased more rapidly than either the mean oil concentration of the cloud or the maximum concentration indicating that some of the dispersed oil was rising back to the surface. The surfacing of dispersed oil was confirmed visually during the experiment. The mixing action of the spray boat and breaker boards apparently created large oil droplets that did not form a stable dispersion. Horizontal diffusion of the dispersed oil was initially more rapid than expected, but the rate of spreading did not increase with time as predicted. The results imply that the scale of diffusion was larger than the scale of turbulence which again can be attributed to the locale of the experiment.

SOME RECENT OBSERVATIONS REGARDING THE UNIQUE CHARACTERISTICS AND EFFECTIVENESS OF SELF-MIX CHEMICAL DISPERSANTS

1977 ◽  
Vol 1977 (1) ◽  
pp. 387-390
Author(s):  
Gerard P. Canevari
Keyword(s):  
Droplet Size ◽  
Oil Spills ◽  
Synergistic Effects ◽  
Toxic Substances ◽  
Mechanical Mixing ◽  
Oil Droplets ◽  
Dispersed Oil ◽  
Study Results ◽  
Micron Diameter ◽  
Spilled Oil

ABSTRACT There has been an increasing awareness of the utility of conventional chemical dispersants in general, and self-mix dispersants in particular as a viable means to minimize damage from oil spills. This paper will update the use of, and activity regarding the self-mix dispersant as noted in applications over the past two years. In addition, those aspects that are still little understood are discussed. Specifically, uniformly sized, dispersed oil droplets of approximately 1 micron diameter are formed by the diffusion action of self-mix chemical dispersants. The droplet size influences the dilution rate of the spilled oil in field applications, and data to support this are presented. The results of laboratory bioassays performed with these much smaller dispersed oil droplets, as opposed to larger droplets formed with mechanical mixing, can be misinterpreted since the increased rate of dilution afforded by smaller droplet size is not replicated. In addition to the vital dilution study results, this paper also presents evidence to clarify several popular misconceptions regarding chemical dispersants. For example, it is explained that the apparent synergistic effects between oil and dispersant do not indicate that chemical dispersants release toxic substances from the oil into the water. Data is also presented which shows that dispersants do not cause the oil to sink.

Characteristics of Oil Droplets Stabilized by Mineral Particles: The Effect of Salinity

2003 ◽  
Vol 2003 (1) ◽  
pp. 963-970 ◽  
Author(s):  
Ali Khelifa ◽  
Patricia Stoffyn-Egli ◽  
Paul S. Hill ◽  
Kenneth Lee
Keyword(s):  
Droplet Size ◽  
Size Distributions ◽  
Oil Droplets ◽  
Natural Sediment ◽  
Mineral Particles ◽  
Sediment Size ◽  
Maximum Value ◽  
Seawater Salinity ◽  
Droplet Size Distributions ◽  
Oil Type

ABSTRACT The influence of salinity on the characteristics of oil droplets stabilized by mineral particles (oil-mineral aggregates – OMA) was studied in the laboratory using three different oils and a natural sediment. Size and concentration of oil droplets associated with negatively and positively buoyant OMA were measured by image analysis using epi-fluorescence microscopy. Results showed that the median droplet size increases rapidly from about 5 μm at zero salinity to double at salinity close to 1.2 ppt; decreases dramatically to about 5 μm at salinity 3.5 ppt and then increases slightly to 6 μm at the seawater salinity. The concentration of oil droplets also increases sharply when the salinity increases from zero to a critical aggregation salinity Scas, after which it stabilizes at its maximum value. The concentration of mineral-stabilized droplets is strongly affected by oil type at any salinity. When normalized to its maximum value, the concentration of droplets correlates well with normalized salinity S/Scas. A relationship is derived to predict the effect of salinity on the concentration of mineral-stabilized droplets. Size distributions of oil droplets follow similar trends, but their magnitudes depend on salinity and oil type. Self-similarity in droplet size distributions was shown when the data were plotted using normalized variables N/Nt and D/D50, where N is the number of droplets of diameter D, Nt is the total number of droplets and D50 the median size of the droplets. With these normalized variables, oil droplet size distributions measured in this study and those measured in field and laboratory under various conditions by different investigators fit the same curve regardless of the formation conditions of the droplets. A function is derived to calculate normalized cumulative size distributions of oil droplets.

Droplet Size Spectrum, Activation Pressure, and Flow Rate Discharged from PWM Flat-Fan Nozzles

2021 ◽  
Vol 64 (1) ◽  
pp. 313-325
Author(s):  
Zhiming Wei ◽  
Heping Zhu ◽  
Zhihong Zhang ◽  
Ramón Salcedo ◽  
Degang Duan
Keyword(s):  
Droplet Size ◽  
Duty Cycle ◽  
Solenoid Valve ◽  
Variable Rate ◽  
Size Distributions ◽  
Flow Rates ◽  
Nozzle Orifice ◽  
Duty Cycles ◽  
Droplet Sizes ◽  
Droplet Size Distributions

HighlightsDroplet sizes, activation pressures acting on nozzle orifices, and flow rates were investigated.Droplet sizes varied with duty cycles, nozzle orifice sizes, and PWM solenoid valve manufacturers.Activation pressures decreased as duty cycles decreased and increased as nozzle orifice sizes decreased.Flow rates increased with increases in both duty cycles and nozzle orifice sizes.Abstract. Pulse width modulated (PWM) spray systems can produce variable spray rates for precision applications of pesticide and fertilizer; however, there are also concerns over their spray performance stability. Droplet size distributions, activation pressures acting on nozzle orifices, and flow rates discharged from nozzles were investigated for test combinations of ten PWM duty cycles (10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%), six flat-fan nozzles with different orifice sizes (XR8001, XR8002, XR8003, XR8004, XR8005, and XR8006), and two PWM solenoid valves from two different manufacturers. Test results showed that the droplet size distribution, activation pressure, and flow rate varied with the duty cycle, nozzle orifice size, and PWM solenoid valve source. For XR8001 and XR8002 nozzles, droplet sizes did not vary significantly with all duty cycles from 10% to 100%. To obtain relatively consistent droplet size distributions, XR8003 and XR8004 nozzles required PWM duty cycles of at least 20%, while XR8005 and XR8006 nozzles required duty cycles of 30% or greater. The activation pressure directly on nozzle orifices increased as the duty cycle increased but decreased as the nozzle orifice size increased. In addition, the same nozzles coupled with PWM solenoid valves from two different manufacturers discharged different flow rates for the same duty cycle in the range of 10% to 90%. Therefore, careful selection of PWM solenoid valves for different orifice nozzles operated at different duty cycles was necessary to achieve consistent variable-rate spray performances. Keywords: Droplet diameter, Variable rate, PWM solenoid valve, Pesticide, Fertilizer, Precision farming.

The Fate of Dispersed Oil Under Ice: Results of JIP Phase 1 Program

2014 ◽  
Vol 2014 (1) ◽  
pp. 949-959
Author(s):  
CJ Beegle-Krause ◽  
Miles McPhee ◽  
Harper Simmons ◽  
Ragnhild Lundmark Daae ◽  
Mark Reed
Keyword(s):  
Literature Review ◽  
Water Column ◽  
Droplet Size ◽  
Fluorescent Dyes ◽  
Autonomous Underwater Vehicles ◽  
The Arctic ◽  
Formation Mechanisms ◽  
Oil Droplets ◽  
Mixing Energy ◽  
Dispersed Oil

ABSTRACT Ice infested waters pose unique challenges to preparedness and response for potential oil spills. An international team of researchers are working together to create a model to aid in evaluating use of dispersants in ice. The model will be designed to evaluate whether or not dispersed oil droplets formed under continuous or concentrated ice could resurface under the ice to form a significant accumulation within two days. The goal is to develop a tool to support contingency planning decisions with respect to dispersant use. Phase I of the project was to perform a literature review to develop recommendations to fill data gaps in the ice, current, and turbulence data needed to run a model. Phase II will include field work to collect data and model development and testing. The model will require information about the oil and dispersed oil droplet size distribution and water column information to predict mixing energy that could keep the oil droplets suspended. Droplet size distributions can be easily measured. The challenge is to provide representative information about the water column. We are evaluating several types of oceanographic observational technologies to collect data on under ice mixing energy such as fluorescent dyes, Turbulent Instrument Clusters (TICs), Autonomous Underwater Vehicles (UAVs), and Acoustic Doppler Current Profilers (ADCPs). From our review, we expect to be able to collect the required environmental parameters within reasonable cost and time. There are a variety of ice formation mechanisms and ice types in the Arctic and Antarctic. Bottom roughness and ice concentration play keys rolls controlling the amount of mixing energy available under the ice. Heavier ice concentrations absorb surface wave energy, which provides the mixing energy for open water dispersant operations. The literature review indicates that good measurements and a good turbulence closure model are key to obtaining good predictions. We are interested in feedback from the IOSC audience regarding our vision of framing the predictive model as an appropriate decision support tool for the Planning and Response Communities.

Investigation of Au droplet formation and growth of SixGe1−x nanowires by molecular beam epitaxy

CrystEngComm ◽  
2020 ◽  
Vol 22 (38) ◽  
pp. 6322-6329
Author(s):  
Felix Lange ◽  
Owen C. Ernst ◽  
Thomas Teubner ◽  
Torsten Boeck
Keyword(s):  
Molecular Beam Epitaxy ◽  
Droplet Size ◽  
Molecular Beam ◽  
Droplet Formation ◽  
Size Distributions ◽  
Subsequent Growth ◽  
Droplet Size Distributions

Characteristic Au droplet size distributions on Si(111) were investigated and correlated to the subsequent growth of SixGe1−x nanowires.

Spray Characteristics of Rotary Micro Sprinkler Nozzles Used in Orchard Pesticide Delivery

2020 ◽  
Vol 63 (6) ◽  
pp. 1845-1853
Author(s):  
Huseyin Guler ◽  
Zhihong Zhang ◽  
Heping Zhu ◽  
Matthew Grieshop ◽  
Mark A. Ledebuhr
Keyword(s):  
Droplet Size ◽  
Delivery Systems ◽  
Orifice Diameter ◽  
List Type ◽  
Spray Drift ◽  
Operating Pressure ◽  
Size Distributions ◽  
Multiple Variable ◽  
Droplet Sizes ◽  
Droplet Size Distributions

HighlightsDroplet sizes were determined for rotary micro sprinkler nozzles used in solid set canopy delivery systems.An empirical multiple-variable model was developed to predict volume median diameters in spray patterns.Sprinkler nozzles produced medium to coarse droplets to minimize pesticide drift in orchards and trellised systems.Droplet size information can be used to select optimal nozzles for either irrigation or pesticide delivery systems.Abstract. Rotary micro sprinkler nozzles can be used for both irrigation and pesticide applications in orchard systems, but little to no information is available on their droplet size distributions. In this study, the droplet size distributions were investigated and described for rotary micro sprinkler nozzles with five different orifice diameters. A particle/droplet laser image analysis system was used to measure droplet spectra at two pressures (207 and 310 kPa) and two radial distances (0.25 and 0.85 m) from the sprinkler nozzle center. Nozzle orifice sizes, rotational speeds, and flow rates were also measured. Droplet sizes varied with the orifice size, operating pressure, and sampling location. Spiral-shaped spray patterns formed due to the spinning discharge port, within which droplet densities varied with location, orifice diameter, and operating pressure. The volume medium diameters (Dv0.5) for green-black, orange-blue, black-black, blue-black, and red-gray nozzles were respectively 317, 338, 379, 352, and 218 µm at 207 kPa and 283, 250, 283, 270, and 222 µm at 310 kPa. An empirical multiple-variable regression model was developed to predict Dv0.5 in the spray patterns discharged from the nozzles. Test results demonstrated that the rotary micro sprinkler nozzles produced medium to coarse droplets that could be used to minimize spray drift while maintaining efficacy in orchard pesticide applications. Keywords: Chemical application, Droplet size, Irrigation, Rotary nozzle, Spray drift reduction.

Ultrasonic Scattering Measurements of Dispersed Oil Droplets in the Presence of Gas

2014 ◽  
Vol 2014 (1) ◽  
pp. 266-282 ◽  
Author(s):  
Paul D. Panetta ◽  
Dale McElhone ◽  
Kyle Winfield ◽  
Grace Cartwright
Keyword(s):  
Natural Gas ◽  
Water Column ◽  
Droplet Size ◽  
Oil Spills ◽  
Acoustic Scattering ◽  
Gas Bubbles ◽  
Deepwater Horizon ◽  
Oil Droplets ◽  
Large Wave ◽  
Dispersed Oil

ABSTRACT To help minimize the effects of oil spills on marine environments, chemical dispersants are used to disperse the oil in the water column so the oil can be consumed by naturally occurring bacteria. During the Deepwater Horizon incident, 1.1 million gallons of dispersant were injected directly into the flowing plume of oil and natural gas over 1500 meters deep. Dispersant's main effect is to decrease the surface tension at the oil-water interface causing the oil to form droplets smaller than ~70 microns so they can remain in the water column. Currently the efficacy of aerial applied dispersants on surface slicks is determined by measuring the droplet size decrease using a Laser In-Situ Scattering Transmissometer (LISST) or by detecting the oil in the water column using fluorometers. LISST instruments are limited to dilute mixtures, below ~500 ppm, because the LISST signal saturates for concentrated mixtures, and their windows can become occluded by oil and biofilms. Fluorometers only measure oil concentration; thus they cannot distinguish between naturally dispersed oil droplets, which can float back to the surface, from chemically dispersed oil droplets, which will remain in the water column to be naturally biodegraded. When gas is present as was the case in the Deepwater Horizon incident where it was estimated that the plume consisted of ~22% natural gas, the LISST cannot distinguish between oil droplets and gas bubbles and thus is not able to track the effectiveness of dispersants in the presence of gas. Acoustic measurements overcome the problems associated with the LISST and fluorometers and are ideal for applications subsurface near a blowout and for low ppm levels expected for surface slicks. One of the key features of the sound wave propagating through the water is the scattering at the interface between the water and object. In previous work we showed the proof of concept to measure the average oil droplet size using acoustic. We used the resonance behavior of the gas bubbles to identify them and separate their contribution to the measured acoustic scattering for various oil and dispersant combinations . We developed acoustic scattering and resonance measurements to track the size of oil droplets in the presence of gas during subsurface releases at SINTEF and in Ohmsett's large wave tank.

scholarly journals A population balance model for large eddy simulation of polydisperse droplet evolution

2019 ◽  
Vol 878 ◽  
pp. 700-739 ◽  
Author(s):  
A. K. Aiyer ◽  
D. Yang ◽  
M. Chamecki ◽  
C. Meneveau
Keyword(s):  
Large Eddy Simulation ◽  
Size Distribution ◽  
Droplet Size ◽  
Droplet Breakup ◽  
Dispersed Phase ◽  
Size Distributions ◽  
Oil Droplets ◽  
One Dimensional ◽  
Eddy Simulation ◽  
Large Eddy

In the context of many applications of turbulent multi-phase flows, knowledge of the dispersed phase size distribution and its evolution is critical to predicting important macroscopic features. We develop a large eddy simulation (LES) model that can predict the turbulent transport and evolution of size distributions, for a specific subset of applications in which the dispersed phase can be assumed to consist of spherical droplets, and occurring at low volume fraction. We use a population dynamics model for polydisperse droplet distributions specifically adapted to a LES framework including a model for droplet breakup due to turbulence, neglecting coalescence consistent with the assumed small dispersed phase volume fractions. We model the number density fields using an Eulerian approach for each bin of the discretized droplet size distribution. Following earlier methods used in the Reynolds-averaged Navier–Stokes framework, the droplet breakup due to turbulent fluctuations is modelled by treating droplet–eddy collisions as in kinetic theory of gases. Existing models assume the scale of droplet–eddy collision to be in the inertial range of turbulence. In order to also model smaller droplets comparable to or smaller than the Kolmogorov scale we extend the breakup kernels using a structure function model that smoothly transitions from the inertial to the viscous range. The model includes a dimensionless coefficient that is fitted by comparing predictions in a one-dimensional version of the model with a laboratory experiment of oil droplet breakup below breaking waves. After initial comparisons of the one-dimensional model to measurements of oil droplets in an axisymmetric jet, it is then applied in a three-dimensional LES of a jet in cross-flow with large oil droplets of a single size being released at the source of the jet. We model the concentration fields using $N_{d}=15$ bins of discrete droplet sizes and solve scalar transport equations for each bin. The resulting droplet size distributions are compared with published experimental data, and good agreement for the relative size distribution is obtained. The LES results also enable us to quantify size distribution variability. We find that the probability distribution functions of key quantities such as the total surface area and the Sauter mean diameter of oil droplets are highly variable, some displaying strong non-Gaussian intermittent behaviour.

scholarly journals Spatial Positioning and Operating Parameters of a Rotary Bell Sprayer: 3D Mapping of Droplet Size Distributions

Fluids ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 165 ◽  
Author(s):  
Adnan Darwish Ahmad ◽  
Binit B. Singh ◽  
Mark Doerre ◽  
Ahmad M. Abubaker ◽  
Masoud Arabghahestani ◽  
...  
Keyword(s):  
Droplet Size ◽  
Flow Rate ◽  
Rotational Speed ◽  
Operating Parameters ◽  
Size Distributions ◽  
Theoretical Formulation ◽  
Wide Range ◽  
Droplet Sizes ◽  
Spatial Positioning ◽  
The Impact

In this study, we evaluated the fundamental physical behavior during droplet formation and flow from a rotary bell spray in the absence of an electrostatic field. The impact of a wide range of operating parameters of the rotary bell sprayer, such as flow rates, rotational speeds, and spatial positioning, on droplet sizes and size distributions using a three-dimensional (3-D) mapping was studied. The results showed that increasing the rotational speed caused the Sauter mean diameter of the droplets to decrease while increasing flow rate increased the droplet sizes. The rotational speed effect, however, was dominant compared to the effect of flow rate. An increase in droplet size radially away from the cup was noted in the vicinity of the cup, nevertheless, as the lateral distances from the cup and rotational speed were increased, the droplet sizes within the flow field became more uniform. This result is of importance for painting industries, which are looking for optimal target distances for uniform painting appearance. Furthermore, the theoretical formulation was validated with experimental data, which provides a wider range of applicability in terms of environment and parameters that could be tested. This work also provides an abundance of measurements, which can serve as a database for the validation of future droplet disintegration simulations.

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