Richard Camilli, Ph.D., Associate Scientist, Applied Ocean Physics & Engineering, Woods Hole Oceanographic Institution
September 24, 2010—Before the National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling
Good morning chairmen and commission members. Thank you for the opportunity to speak today about the flow rate and fate of oil from the Deepwater Horizon disaster. My name is Richard Camilli. I am a Scientist in the Woods Hole Oceanographic Institution’s Department of Applied Ocean Physics and Engineering.
This past May, at the request of the US Coast Guard, I led a team of researchers in a study to estimate the flow rate and total spill volume from the Deepwater Horizon’s Macondo well. This investigation was undertaken using advanced acoustic technologies during well containment operations.
We integrated our equipment onto a remotely operated vehicle and operations commenced immediately following termination of the ‘top kill’ attempt. Our investigation was conducted on a non-interference basis, exactly as described in my prior Congressional testimony. Less than 48 hrs after completing field operations, my analysis team and I provided an initial flow estimate of 0.12 to 0.23 m3/s. Following more detailed calculations, using over 16,000 discrete Doppler velocity measurements and 2,600 individual sonar cross section measurements, we revised our estimate upward by 8% to 0.25 m3/s. These flow rates were, at that time, described as bulk volumetric rates because we had no accurate information as to fluid composition and BP had denied clearance for my team to use isobaric samplers to collect and analyze end member fluids from the leak.
Through the continued support of the Coast Guard, and the direct involvement of USGS Director, Dr. Marcia McNutt, I was authorized to lead a second team back to the Deepwater Horizon site and collect end member fluids from within the LMRP ‘top hat’ using the same samplers that had previously been prohibited by BP. Based on compositional analysis, and the previously measured volumetric flow rate I calculated the oil flow at 59,000 bbl/day, as of May 31st.
Using this estimate and the DOE’s measured pre shut-in flow rate of 53,000 bbls/day, I extrapolated a linear trend for the interval between April 20th and July 14th and calculated a cumulative leak of 5 million barrels. Subtracting the collected oil from this total yields a net 4.2 million barrels released to the ocean.
This estimate does not take into account flow rate change resulting from riser shearing, the oil that burned prior to the platform’s sinking, or minor subsequent refinements in our oil composition analysis. These factors offset each other and I therefore do not expect the 4.2 million barrel estimate to undergo significant revision. Neglecting these considerations, the WHOI team’s findings are within 2% of the official government estimate.
Based on subsurface oil emulsion layers I observed during the flow rate investigation, I submitted a proposal to the National Science Foundation to map subsurface hydrocarbon plumes using an autonomous underwater vehicle equipped with a mass spectrometer. As Chief Scientist I led another expedition back to the MC252 block. Our investigation revealed a continuous subsurface hydrocarbon plume over 35 km long, 2 km wide, and 200m high, traveling in a southwesterly direction at an average rate of 6.7km/day at 1100 meters depth. We determined that the plume’s origin was the Macondo well, but that it did not create hypoxic ‘dead zones’ that would threaten fisheries. Our findings are detailed in a paper published in Science. Other studies provide additional insight into microbial degradation of these subsurface hydrocarbons. The emerging body of evidence indicates that biodegradation within these plumes was predominately limited to low molecular weight alkanes, mainly propane. Questions remain as to the transport and fate of more recalcitrant oil components, particularly aromatic and polycyclic aromatic hydrocarbons (many of which are known carcinogens).
Other important aspects of assessment should be systematically addressed, including survey of sediment contamination, and long term monitoring of the Mississippi Canyon block and surrounding areas. I am prepared to describe field-proven technologies for high-speed non-contact sediment contamination mapping, and systems for monitoring water column contamination over extended periods.
I would like to close by acknowledging the significant assistance provided by individuals within many governmental, academic, and industrial organizations. Throughout these investigations my colleagues and I have sought to remain sensitive to the lives lost in this tragedy, their families, the many residents of the Gulf Coast who have been impacted, as well as the ongoing assessment and cleanup efforts. We will continue to assist our nation and its cognizant agencies to the fullest extent possible when called upon. In order to avoid subjective biases or factual misrepresentation, we made a conscious decision to present findings publicly only after scientifically rigorous vetting or peer review.
Dr. Richard Camilli