Study Identifies Source of Oil Sheens Near Deepwater Horizon Site

Posted In Gulf Oil Catastrophe, News
Jul
20

oil-ocean
Oil in the wake. Oil in the boat wake at the Deepwater Horizon site. Captions and Photo source: NOAA

By NSF,

A chemical analysis indicates that the source of oil sheens recently found floating at the ocean’s surface near the site of the Gulf of Mexico Deepwater Horizon oil spill is pockets of oil trapped within the wreckage of the sunken rig.

First reported to the U.S. Coast Guard by multinational oil and gas company BP in September 2012, the oil sheens raised public concern that the Macondo well, which was capped in July 2010, might be leaking.

However, both the Macondo well and the natural oil seeps common to the Gulf of Mexico were confidently ruled out, according to researchers from the University of California Santa Barbara (UCSB) and the Woods Hole Oceanographic Institution (WHOI).

The results are published this week in the journal Environmental Science & Technology.

“Silver linings in the dark cloud of the Deepwater Horizon spill are very hard to come by,” says Don Rice, program director in the National Science Foundation’s (NSF) Division of Ocean Sciences, which funded the research.

“Among the precious few are the lessons we’ve learned about the marine biogeochemistry of petroleum mixtures. This team has demonstrated convincingly that we can also use what we have learned for forensic purposes.”

The researchers used a recently patented method to fingerprint the chemical makeup of the oil sheens, and to estimate the location of the source based on the extent to which gasoline-like compounds evaporated from the sheens.

“The results demonstrate a recently developed geochemical analytical method and may have real-world implications in environmental management strategies for future contamination incidents,” says Deborah Aruguete, program director in NSF’s Division of Earth Sciences, which co-funded the research.

Because every oil sample contains chemical clues pointing to the reservoir it came from, scientists can compare it to other samples to determine if they share a common source.

“This appears to be a slow leak from the wreckage of the rig, not another catastrophic discharge from a deep oil reservoir,” says geochemist David Valentine of UCSB.

“Continued oil discharge to the Gulf of Mexico from the wreckage of the Deepwater Horizon rig is not a good thing, but there is some comfort that the amount of leakage is limited to the pockets of oil trapped within the wreckage of the rig.”

Valentine and WHOI’s Chris Reddy have worked on Deepwater Horizon for much of the last three years, investigating a wide range of problems, including the composition of the oil, detection of subsurface plumes, the biodegradation of the oil, the fate of the dispersants and the chemical transition from floating oil slicks to sunken tar balls.

“Because of our ongoing funding from NSF, we were prepared to interrogate the source of mysterious oil sheens in the Gulf of Mexico,” said Valentine.

“We’ve been exploring new ways to do this for several years in the context of natural seeps, and this event provided us an opportunity to apply our fundamental advances to a real-world problem.”

The scientists analyzed 14 sheen samples skimmed from the sea surface during two trips to the Gulf of Mexico.

Using comprehensive two-dimensional gas chromatography, a technique developed in Reddy’s lab, the researchers first confirmed that the sheens contained oil from the Macondo well.

But the sheen samples also contained trace amounts of olefins, industrial chemicals used in drilling operations. The presence of olefins provided a fingerprint for the sheens the scientists could compare to the samples they had analyzed during the last three years.

Olefins are not found in crude oil and their uniform distribution in the sheens indicated that the Macondo well was unlikely to be the source.

The team surmised that the sheens must be coming from equipment exposed to olefins during drilling operations.

“The occurrence of these man-made olefins in all our sheen samples points to a single main source, which contains both Macondo oil and lesser amounts of the drilling fluids that harbor the olefins,” said Valentine.

“This pointed us to the wreckage of the rig, which was known to have both, as the most likely source for the sheens.”

The researchers compared the sheen samples to other field samples, some of which they expected would contain olefins and some they thought would not.

The reference samples included two pieces of debris from the Deepwater Horizon found floating in May 2010, as well as oil collected by BP in October 2012, during an inspection of the 80-ton cofferdam that had been abandoned at the seafloor after its use in a failed attempt to cover the Macondo well in 2010.

The team’s gas chromatography analysis of BP’s cofferdam samples definitively showed that it was not the sole source of the leak as there were no olefins present.

Prior to the analysis the cofferdam had become the prime suspect as the source when BP found small amounts of oil leaking from its top.

BP scientists acquired oil samples from this leak point before sealing the leak, thinking they had resolved the problem. However, the sheens on the sea surface persisted, and the lack of olefins pointed to another source entirely.

When Valentine and Reddy compared the chemical makeup of the sheens with debris found floating in 2010, they found a match. That debris, which came from the rig itself, was coated with oil and was contaminated by drilling mud olefins.

“The ability to fingerprint synthetic hydrocarbons allowed us to crack this case,” Valentine said. “We were able to exclude a number of suspects and match the olefin fingerprint in the new oil slicks to that of the wreckage from the sunken rig.”

The chemical analysis also told researchers which sheens had surfaced more recently than others, allowing them to reconstruct a trajectory for local ocean currents that pointed back to the oil’s source.

By looking for sheens that showed the least amount of evaporation, they determined that oil surfaced closer to Deepwater Horizon wreckage than to the cofferdam site.

To explain how the oil might be trapped and released from the wreckage, the scientists point out that when the Deepwater Horizon rig sank, it was holding tanks containing hundreds of barrels of a mixture of drilling mud and oil.

Over time, corrosive seawater can create small holes through which oil can slowly escape to the surface. The researchers suspect that the containers on the rig holding trapped oil may be the source of the recent oil sheen.

In addition to Valentine and Reddy, the research team consisted of Christoph Aeppli and Robert Nelson of WHOI, and Matthias Kellermann of UCSB.

The Gulf of Mexico Research Initiative, Woods Hole Oceanographic Institution and a Swiss National Science Foundation Postdoctoral Fellowship also funded the research.

Original Article, NSF

Crews Work to Seal Leaking Oil and Gas Well off Louisiana Coast, Washington Post (Uploaded 07-10-2013)

Gulf Oil Spill Cleanup Ends As BP Pulls Out, Leaves Unanswered Questions (Uploaded 06-17-2013)

BP Appeal Over ‘Absurd’ Gulf Oil Spill Payouts, BBC News (Uploaded 03-16-2013)

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Resources

Federal

  • Deep Water Horizon Response is the official site of the incident in conjunction with BP, DOI, NPS, USGS, CDC, USFWS, NOAA and other branches of the US government (collectively called Unified Command). Information, including the latest news, photos, area plans, and volunteer information.
  • NOAA is a government program that uses science and research to protect life, property and natural resources. This NOAA site provides maps of the spill and related statistics, including a trajectory forecast map for the oil spill.
  • The Environmental Protection Agency provides data on Air, Land, and Water pollutants including sampling maps and contaminant levels.

Louisiana

  • Volunteer Louisiana is the official site for the State of Louisiana to get involved in the spill response.
  • The Louisiana Department of Wildlife and Fisheries provides maps of closures to fishing areas in LA.
  • The Louisiana Emergency Office has made Google Earth files of the spill available to the public here http://gohsep.la.gov/oilspill.aspx and also has current information on general closures of waterways, photos, and reports.
  • The Audubon Nature Institute site provides a number for citizens to call if turtles, manatees, dolphins, or other animals are in distress
  • The Oiled Wildlife Care Network is a CA based non-profit is advising folks in the Gulf of Mexico on best practices and provide resources on how people can help.
  • The Coalition to Restore Coastal Louisiana is a non-profit organization who strive to protect and restore coastal Louisiana. Volunteers are needed for numerous actions including: monitoring, oiled wildlife recovery, boat driving, or simple monetary donations.
  • The Greater New Orleans Foundation is a philanthropic organization in Louisiana and the surrounding region that joins with other non-profit, foundations and community and government officials to address the needs of the community. The Foundation has opened the Gulf Coast Oil Spill Fund.
  • The Louisiana Bucket Brigade is an environmental health and justice organization working with communities near oil refineries and chemical plants. They aid residents in these regions to reduce pollution and protect public health. The Brigade has formed an incident map where you can report observed signs of oil.

Alabama

  • The Alabama Coastal Foundation is an education based organization whose mission is to project the quality of Alabama’s coastal resources. They are currently training volunteers to help directly with the spill response.
  • The site by the Alabama Governor’s Office of Faith-Based and Community Initiatives gives basic phone numbers.
  • The Mobile Bay National Estuary Program is an organization funded by the EPA fighting the environmental challenged facing Mobile Bay. This site gives e-mail addresses and phone numbers to help and provides basic information.
  • The Mobile Bay Keeper is a group of citizens who are interested in preserving the Mobile Bay watershed as well as protecting the health of the individuals and environment in the Bay. Check out the latest information about the spill and learn how to become a member and donate to the cause.

Mississippi

Florida

  • The Florida Department of Environmental Protection is the lead agency in FL and this website provides the most thorough information in the state.
  • Volunteer Florida, the website of the Governor’s Commission on Volunteerism and Community Service and the State Emergency Response Team, lists volunteer opportunities by county.
  • The Escambia County site provides summary points of actions taken by BP and FL with a focus on the County.
  • The Pinellas County site is a concise list of related local websites and numbers for information.
  • The Gulf County site has current news on the spill as it relates to the county
  • Volunteer directly with the largest wild bird hospital in the United States, the Suncoast Seabird Sanctuary.

Organizations and other networks

  • American Birding Association
  • Audubon is a global leader in protecting birds and other wildlife and their habitats. They are partnering with other organizations.
  • The Sierra Club is a grassroots environmental organization that works to protect communities, wild places, and the planet. Updates on the oil spill, as well as volunteer and donation information.
  • The Nature Conservancy is a conservation organization with a mission to preserve and protect ecologically significant lands and waters for nature and people. Learn more about the oil spill and how to help out at http://www.nature.org/wherewework/northamerica/states/alabama/features/oilspill.html and check out their blog.
  • Sea Grant is nationwide network (administered through NOAA) of 32 university-based programs that work with coastal communities on environmental stewardship and the responsible use of our coasts. The Gulf of Mexico Sea Grant Programs provides resources to educators with research that may be impacted by the spill.
  • The National Wildlife Federation is America’s largest conservation organization whose mission is to protect and restore wildlife habitat, confront global warming and connect with nature. Get the latest information on the oil spill crisis and how to help.
  • The mission of Tri-State Bird Rescue and Research is to provide rehabilitation of injured, orphaned, and oiled native wild birds to return to their natural environment. Donate to their research.
  • Green Peace is an international organization that strives to save the planet from environmental threats such as global warming, destruction of forests and deterioration of the oceans. Follow their blog and learn how to take action.
  • Global Green USA is an international environmental non-profit organization with an office in New Orleans that strives to fight global climate change, eliminate weapons of mass destruction and create clean, safe drinking water for all. Follow their blog and get involved.
  • Matter of Trust is a non-profit organization focused on materializing sustainable systems by mimicking Mother Nature as well as concentrating on manmade surplus, natural surplus and eco-educational programs. Learn very simple ways to help the oil spill crisis.
  • The official Facebook page of Unified Command.
  • BP Gulf of Mexico response.