YubaNet.com
Tuesday, September 23 2014

            We Deliver News to the Sierra
News Fire News spacer Latest News spacer Regional News spacer California News spacer USA News spacer World News spacer Op-Ed spacer Enviro News spacer Sci Tech News spacer Life spacer Odd News spacer Cartoons spacer
Features The Calendar features features Weather features Sierra NightSky features features features Road Conditions features Home spacer
Sci/Tech
 

Gulf of Mexico: Numerical study suggests subsea injection of chemicals didn't prevent oil from rising to sea surface

Groundbreaking 3D models show that oil droplets were too small for dispersants to have significant impact

    Google+    

By: University of Miami Rosenstiel School of Marine & Atmospheric Science

50553_web.jpg
This is a time sequence of the simulated 3D spatial distribution of oil products below the surface based on current advection and oil buoyancy in the region. The color-bar indicates the size of individual oil droplets for the hypothetical scenario without deep injection of dispersant. The formation of the prominent deep hydrocarbon plume (blue) and the layering of shallower plumes demonstrates that chemical dispersants injected at the wellhead were likely not effective in changing the amount of oil reaching the surface. These findings appear in a new article in Environmental Science and Technology. The oil in the top 20 m of the sea surface is not shown (e.g., transport of oil reaching the surface is not depicted). Credit: Claire Paris, et. al.
MIAMI, December 4, 2012 - The 2010 blowout of the Macondo well in the waters of the Gulf of Mexico resulted in the region's largest oil spill in U.S. history. As the Deepwater Horizon (DWH) incident unfolded, in an effort to prevent the oil from coming to the surface and reaching coastal and marsh ecosystems, chemical dispersants were injected at the wellhead. These powerful dispersants, typically used to break up oil slicks at the sea surface had never been used in such large quantities and over such a prolonged period of time in the deep ocean.

A new study published in Environmental Science & Technology, led by University of Miami (UM) Rosenstiel School of Marine & Atmospheric Science Associate Professor of Applied Marine Physics Claire Paris, is the first to examine the effects of the use of unprecedented quantities of synthetic dispersants on the distribution of an oil mass in the water column, based on a modeling approach. The team of researchers included UM Rosenstiel School Assistant Scientist Matthieu Le Henaff and Research Associate Professor Villy Kourafalou, UM Center for Computational Science (CCS) Scientist Judith Helgers and Research Associate Professor Ashwanth Srinivasan, Ph.D. Candidate Zachary Aman from Colorado School of Mines, Research Associate Professor Ajit Subramaniam from Lamont Doherty Earth Observatory at Columbia University, and Professor Dong-Ping Wang from the School of Marine and Atmospheric Science of SUNY at Stony Brook. Together they developed and tested models to show that the application of oil-dispersing chemicals had little effect on the oil surfacing in the Gulf of Mexico.

"Deepwater drilling into large, high-pressure reservoirs of oil and gas located far offshore and hundreds of meters below the ocean's surface involves risks for which we were not adequately prepared," said Paris. "As the oil gushed uncontrolled into the Gulf, injection of chemical dispersant into the deep ocean may have had little effect because the oil was coming out with such pressure that it was already dispersed in small droplets. It is impossible to know whether the synthetic dispersant was well mixed with the oil as it was injected. Our models treat both scenarios, and regardless of whether you have the dispersant in the water mixture or not, the amount of oil reaching the sea surface remained relatively unchanged."

The researchers estimated the distribution of oil droplet sizes with and without injection of dispersant at the wellhead. They then applied a novel oil-mass tracking model of the Connectivity Modeling System (CMS) developed shortly after the DWH incident with a RAPID award from the National Science Foundation (NSF) and presented a three-dimensional simulation of the DWH spill showing the unfolding of the disaster to examine the effect the synthetic dispersant may have had on the oil transport in the water column. The model indicated that the dispersant injected at BP's Macondo wellhead was not necessary to break up the oil. The subsea application of dispersant did not have its expected outcome.

"This study is notable because it presents a comprehensive estimate of the Macondo blowout from the microscopic oil-water interface through the macroscopic transport of crude oil." said chemical engineer Aman. The work served as a milestone in assessing the three dimensional transport of oil in the water column.

"Since the beginning of the spill our model accurately predicted the decoupling between the surface and subsea oil transport, and was unique in showing the southwest extension of the deep plume," said physical oceanographer Le Henaff. "Correct assessment of upwelling and downwelling currents for the circulation model created a realistic scenario that we then used to test the effect of the injection of dispersant on the oil partition."

As global deep-sea oil exploration expands, the model will be helpful in quantifying the utility of synthetic dispersants for deep water oil leaks. "The CMS oil model was able to predict the strange layering of oxygen deficit anomalies that we observed during our field sampling and provided us a three dimension view of a phenomena that was constantly changing in time. For us, it was like being able to track the ghosts of the oil plume because the oil itself had been consumed by the microbes and all that was left were the oxygen anomalies and the model was critical for us to understand what we were observing in the field," said biological oceanographer Subramaniam.

These findings expand on a previous study published earlier this year in which the team studied the crucial role of wind-induced surface drift on the fate of the oil in the Gulf of Mexico. "This current study reveals unexplored pathways of the oil transport by underwater currents and highlights the importance of topographic interactions and vertical flows in moving the deep plume toward deep waters or up the water column." said physical oceanographer Wang.

This study was supported by the NSF-RAPID OCE 1048697 award to C. Paris. The contribution of Paris and Kourafalou were also made possible in part by grants from The Gulf of Mexico Research Initiative, to the Center for Integrated Modeling and analysis of the Gulf Ecosystem (C-IMAGE) and the Deep Sea to Coast Connectivity in the Eastern Gulf of Mexico (DEEP-C), respectively. The Metcalf Institute for Marine & Environmental Reporting at the University of Rhode Island Graduate School of Oceanography was essential in bringing a chemical engineer, Zachary Aman, to the team via the NSF-RAPID DRL-10-55381 to Sunshine Menezes.

The CCS has emerged as a leader in providing a robust cyber infrastructure designed to address major computational challenges, and is now recognized among the State's top academic centers, and is gaining national prominence for its work. Its high performance computer core supports work a variety of fields such as genomics, computational biology, marine ecosystems modeling, climate and meteorology, computational fluid dynamics and social systems informatics. For more information, please visit www.ccs.miami.edu

 

Help us bring you more news. Be a real reader: Support YubaNet

By submitting a comment you consent to our rules. You must use your real first and last name, not a nickname or alias. A comment here is just like a letter to the editor or a post on Facebook. Thank you.

 

Latest Headlines

Sci/Tech

Study links Arctic sea ice loss to cold air in middle latitudes in North America, Europe and Asia

Study helps assess impact of temperature on belowground soil decomposition

NASA's MAVEN Spacecraft Reaches Mars

Monster galaxies gain weight by eating smaller neighbours

World Rhino day 2014: Research to help rhinos survive

The Jimmy Durante of dinosaurs : new hadrosaur noses into spotlight

Creating Pancakes using Galaxy Collisions-Violent Origins of Disk Galaxies Probed by Radio Telescopes

Early Earth less hellish than previously thought

219 million stars: Astronomers release most detailed catalogue ever made of the visible Milky Way

Scientists Report First Semiaquatic Dinosaur, Spinosaurus


More

 

 

 

 

NEWS . Fire News . Latest . Regional . California . USA . World . Op-Ed . Enviro . Sci/Tech . Life . Odd News . Cartoons
FEATURES . The Calendar .Weather . Sierra NightSky . Horoscope . Road Conditions
YubaNet.com . Advertising. About Us . Support YubaNet . Contact Us . Terms of Use . Privacy

YubaNet.com © 1999-2014
Nevada City, California (530) 478-9600