Marcia McNutt

Review of flow rate estimates of the Deepwater Horizon oil spill

The unprecedented nature of the Deepwater Horizon oil spill required the application of research methods to estimate the rate at which oil was escaping from the well in the deep sea, its disposition after it entered the ocean, and total reservoir depletion. Here, we review what advances were made in scientific understanding of quantification of flow rates during deep sea oil well blowouts. We assess the degree to which a consensus was reached on the flow rate of the well by comparing in situ observations of the leaking well with a time-dependent flow rate model derived from pressure readings taken after the Macondo well was shut in for the well integrity test. Model simulations also proved valuable for predicting the effect of partial deployment of the blowout preventer rams on flow rate. Taken together, the scientific analyses support flow rates in the range of ∼50,000–70,000 barrels/d, perhaps modestly decreasing over the duration of the oil spill, for a total release of ∼5.0 million barrels of oil, not accounting for BPs collection effort. By quantifying the amount of oil at different locations (wellhead, ocean surface, and atmosphere), we conclude that just over 2 million barrels of oil (after accounting for containment) and all of the released methane remained in the deep sea. By better understanding the fate of the hydrocarbons, the total discharge can be partitioned into separate components that pose threats to deep sea vs. coastal ecosystems, allowing responders in future events to scale their actions accordingly.

Science in support of the Deepwater Horizon response

This introduction to the Special Feature presents the context for science during the Deepwater Horizon oil spill response, summarizes how scientific knowledge was integrated across disciplines and statutory responsibilities, identifies areas where scientific information was accurate and where it was not, and considers lessons learned and recommendations for future research and response. Scientific information was integrated within and across federal and state agencies, with input from nongovernmental scientists, across a diverse portfolio of needs—stopping the flow of oil, estimating the amount of oil, capturing and recovering the oil, tracking and forecasting surface oil, protecting coastal and oceanic wildlife and habitat, managing fisheries, and protecting the safety of seafood. Disciplines involved included atmospheric, oceanographic, biogeochemical, ecological, health, biological, and chemical sciences, physics, geology, and mechanical and chemical engineering. Platforms ranged from satellites and planes to ships, buoys, gliders, and remotely operated vehicles to laboratories and computer simulations. The unprecedented response effort depended directly on intense and extensive scientific and engineering data, information, and advice. Many valuable lessons were learned that should be applied to future events.

Applications of science and engineering to quantify and control the Deepwater Horizon oil spill

The unprecedented engagement of scientists from government, academia, and industry enabled multiple unanticipated and unique problems to be addressed during the Deepwater Horizon oil spill. During the months between the initial blowout on April 20, 2010, and the final well kill on September 19, 2010, researchers prepared options, analyses of tradeoffs, assessments, and calculations of uncertainties associated with the flow rate of the well, well shut in, killing the well, and determination of the location of oil released into the environment. This information was used in near real time by the National Incident Commander and other government decision-makers. It increased transparency into BP’s proposed actions and gave the government confidence that, at each stage proposed, courses of action had been thoroughly vetted to reduce risk to human life and the environment and improve chances of success.

Scientific basis for safely shutting in the Macondo Well after the April 20, 2010 Deepwater Horizon blowout

As part of the government response to the Deepwater Horizon blowout, a Well Integrity Team evaluated the geologic hazards of shutting in the Macondo Well at the seafloor and determined the conditions under which it could safely be undertaken. Of particular concern was the possibility that, under the anticipated high shut-in pressures, oil could leak out of the well casing below the seafloor. Such a leak could lead to new geologic pathways for hydrocarbon release to the Gulf of Mexico. Evaluating this hazard required analyses of 2D and 3D seismic surveys, seafloor bathymetry, sediment properties, geophysical well logs, and drilling data to assess the geological, hydrological, and geomechanical conditions around the Macondo Well. After the well was successfully capped and shut in on July 15, 2010, a variety of monitoring activities were used to assess subsurface well integrity. These activities included acquisition of wellhead pressure data, marine multichannel seismic profiles, seafloor and water-column sonar surveys, and wellhead visual/acoustic monitoring. These data showed that the Macondo Well was not leaking after shut in, and therefore, it could remain safely shut until reservoir pressures were suppressed (killed) with heavy drilling mud and the well was sealed with cement.

Paleomagnetism of northern Cocos seamounts: Constraints on absolute plate motion

Paleodeclinations of several small seamounts on the northern Cocos plate demonstrate that it rotated approximately 30° counter-clockwise about a pole close to its northern boundary during the past 1 to 6 m.y. Paleoinclinations agree with models of absolute plate motion in which the northern component of velocity for the Cocos plate is about 50 mm/yr. The paleomagnetic data, dredge samples, and seamount morphology, either independently or in concert, are reasonably reliable for distinguishing fault blocks from central volcanoes and for determining the approximate age of a structure relative to that of the surrounding sea floor.

Gravity field over the former Soviet Union mapped

The gravity field of our planets largest continental land mass was virtually terra incognita for most scientists prior to the creation of a data set now available in the public domain. Recently, the 1°×1° averaged free-air gravity anomalies over the former Soviet Union (FSU) were placed at the Bureau Gravimetrique International as an “open file” by the International Scientific Environmental Center of the Russian Academy of Sciences. The survey to develop the data set cost more than

Marcia K. McNutt awarded 1988 Macelwane Medal

2 billion.

1985 Bowie Medal to H. William Menard

It is an honor for me, and a pleasure, to present to you Marcia McNutt as a Macelwane medalist for 1988. McNutt is a tectonophysicist, best known for her work on the thermal and mechanical properties of the lithosphere and the nature of isostatic compensation beneath the oceans and continents. Large topographic loads with horizontal scale lengths from a few tens to hundreds of kilometers are a rich source of information about the dynamical properties of Earths outer layers. Although such features have been studied for more than a century, it has only been within the last decade, in large measure through the work of McNutt and her colleagues, that the quantitative modeling of loading phenomena has elucidated the physics of lithospheric deformation and the nature of lithospheric interactions with the convecting mantle. This Macelwane Medal recognizes her achievements in this important area of tectonophysics.

Constraints on yield strength in the oceanic lithosphere derived from observations of flexure

Today we are here to award the Bowie Medal, the highest honor bestowed by the American Geophysical Union, to Henry William Menard. Bill Menards outstanding contributions to geological sciences span 4 decades, making him one of only a handful of geologists of his generation to survive, and go on to lead, the plate tectonic revolution. Bill has given us ocean basins and rises, fracture zones and depth anomalies, crenelate ridges and pivoting subduction. His books on the history and sociology of science are well respected by experts in the field. For those of us who would aspire to some measure of significance and longevity in our own careers, it is appropriate on this occasion to catalogue some of Bills attributes, which continue to sustain a lifetime of achievement.