RAPID: Mapping Subsurface Hydrocarbon Plume Distribution and Structure near MC Block 252

Woods Hole Oceanographic Institution, Woods Hole MA

Investigators

Abstract

The Deepwater Horizon disaster has released more than 20 million gallons of oil into the Gulf of Mexico. Due to the extreme depth and broad area of impacted region, it is critical that the presence and structures of oil plumes be determined for accurate mass balance calculations, estimating damage, and understanding the overall chemical/physical behavior of individual hydrocarbons comprising the oil. There exists considerable uncertainty on the presence of subsurface plumes reported by other researchers. The latter is due, in part, because the findings are based on in situ fluorescence typically used to measure dissolved organic matter. In addition, these findings only provide an estimate of total oil. To provide a robust and higher resolution dataset on the hydrocarbon distribution and structure in the Gulf of Mexico, researchers at the Woods Hole Oceanographic Institution will deploy the TETHYS in-situ mass spectrometer. TETHYS compliments conventional sampling by providing near-continuous records and by providing far greater spatial resolution. Additionally, real time feedback from TETHYS can be used to guide conventional sampling. The TETHYS in-situ mass spectrometer is optimized for long-term unattended environmental monitoring of low molecular weight (2-200 amu) gases and volatile chemicals in a variety of hostile environments. TETHYS is also unique among field-portable or underwater mass spectrometers in that it retains high mass resolution in the low-mass range (1-25 amu), allowing it to quantify hydrogen, helium, and methane. In this study of the Deepwater Horizon spill, TETHYS will be deployed on two different subsea platforms: an enhanced CTD rosette and the autonomous underwater vehicle (AUV) Sentry. The research team will work collaboratively with a number of other investigators from Woods Hole, Texas A & M University, and the University of California at Santa Barbara who have separately received RAPID funding to study various aspects of this historic oil spill. All of these investigators have prior experience with the TETHYS/CTD/Sentry technology. Broader Impacts: Results from this research are expected to contribute to a deeper understanding of petroleum fate and carbon cycling in the Earth system. Knowledge gained from this research will also be translated and transmitted directly to state and federal agencies involved in the spill damage assessment and restoration. The project will provide the concepts, processes, and parameters necessary for existing industry oil spill models to be adapted to the unparalleled situation of a major oil release on the deep sea floor. The continued expansion of offshore drilling operations into deeper waters may lead inevitably to the risk of more spills in the future.