More than seven years after the Deepwater Horizon drilling rig exploded, sending up to 900,000 tons of oil and natural gas into the Gulf of Mexico, there are lingering questions about the safety and effectiveness of a key element of the emergency response: injecting chemicals a mile below the ocean surface to break up oil spewing from the ruptured sub-sea wellhead to prevent them from reaching environmentally sensitive regions.
In a groundbreaking study published today in the Proceedings of the National Academy of Sciences, collaborators from the Woods Hole Oceanographic Institution, New Jersey Institute of Technology, Texas A University and the Swiss Federal Institute of Aquatic Science and Technology pooled their scientific and technical expertise to provide some of the first answers to these controversial policy questions.
The team began by developing physical models and computer simulations to determine the course the oil and gas took following the eruption, including the fraction of larger, more buoyant droplets that floated to the surface and the amount of smaller droplets entrapped deep below it due to sea stratification and currents.
Michel Boufadel, director of NJIT's Center for Natural Resources Development and Protection (NRDP) and Lin Zhao, a post-doctoral fellow at the center, developed a model to predict the size of droplets and gas bubbles emanating from the wellhead during the sub-surface blowout.
Researchers at Texas A in turn created a model to study the movement of pollutants away from the wellhead.
The researchers determined that the use of dispersants had a substantial impact on air quality in the region of the spill by reducing the amount of toxic compounds such as benzene that reached the surface of the ocean, thus protecting emergency workers on the scene from the full brunt of the pollution.