585
information available previous to the Deepwater Horizon (DWH) accident, document critical knowledge acquired since the DWH spill, and briefly discuss priority
science areas for the prevention of future deep blowouts and for minimizing, to the
extent practicable, the impacts from them on the environment, to response workers,
and to the public. This review is not intended to be comprehensive, but highlights
some of the most significant and pressing issues in deep spill science.
34.2 What We Knew Then…
The schematic diagram presented in Chap. 1, (Fig. 1.1) provides a mechanistic summary of documented and potential relationships between nominal “blowout scenarios,” ambient deep-sea conditions, the use of various mitigation techniques, and
the ultimate impacts of the resulting contamination and corresponding response
measures as they affect ecosystem components, processes, and people. While much
was known previously about the top 1/3 of that diagram (e.g., related to surface oil
spills), the bottom 2/3 (e.g., especially the deep sub-sea processes and outcomes)
was largely unknown and unanticipated prior to DWH (“unknown-unknowns”).
The Ocean Studies and Marine Boards of the National Research Council (Ocean
Studies Board and Marine Board 2003) outlined a schematic of oil fate including
sedimentation, but this diagram primarily described inter- and subtidal near coastal
processes (their Fig. 4.1).
A number of experiments and integrated plume models (Johansen 2000; Chen
and Yapa 2001) predicted the formation of subsurface plumes or layers of dissolved
hydrocarbons and micro-droplets of liquid oil owing to the dynamics of blowouts
prior to DWH. These results were summarized in a cautionary report by the Ocean
Studies and Marine Boards of the National Research Council (Ocean Studies Board
and Marine Board 2003) suggesting the formation of such plumes in the advent of
a well control accident in the deep sea. In a quintessential understatement, however,
the NRC noted: “The present understanding of deepwater releases suggests they are
much more complicated than those in shallow water.” Indeed.
Experiments conducted prior to DWH examined oil droplet formation, size composition, and impacts of dispersants from turbulent “jets” similar to a severed pipe
scenario. While some theoretical work had been conducted on the behavior and fate
of oil and gas under extreme pressure (Masutani and Adams 2000; Socolofsky and
Adams 2005), research was largely disconnected from the rapid expansion of oil
and gas exploration and production into the ultra-deep (>1500 m; Murawski et al.
2020a). It was not until the C-IMAGE consortium initiated experiments with
methane- saturated (“live”) oil, under relevant pressure and ambient temperature
conditions (e.g., 15 MPa at 4.5 °C in the case of DWH), and simulating pressure
drops as calculated from the actual well casualty (McNutt et al. 2011), that laboratory experiments became sufficiently sophisticated to mirror the likely important
mechanisms leading to the formation of oil droplets small enough to remain
34 Summary of Progress on Major Research Issues: Deep-Sea Oil Spills
information available previous to the Deepwater Horizon (DWH) accident, document critical knowledge acquired since the DWH spill, and briefly discuss priority
science areas for the prevention of future deep blowouts and for minimizing, to the
extent practicable, the impacts from them on the environment, to response workers,
and to the public. This review is not intended to be comprehensive, but highlights
some of the most significant and pressing issues in deep spill science.
34.2 What We Knew Then…
The schematic diagram presented in Chap. 1, (Fig. 1.1) provides a mechanistic summary of documented and potential relationships between nominal “blowout scenarios,” ambient deep-sea conditions, the use of various mitigation techniques, and
the ultimate impacts of the resulting contamination and corresponding response
measures as they affect ecosystem components, processes, and people. While much
was known previously about the top 1/3 of that diagram (e.g., related to surface oil
spills), the bottom 2/3 (e.g., especially the deep sub-sea processes and outcomes)
was largely unknown and unanticipated prior to DWH (“unknown-unknowns”).
The Ocean Studies and Marine Boards of the National Research Council (Ocean
Studies Board and Marine Board 2003) outlined a schematic of oil fate including
sedimentation, but this diagram primarily described inter- and subtidal near coastal
processes (their Fig. 4.1).
A number of experiments and integrated plume models (Johansen 2000; Chen
and Yapa 2001) predicted the formation of subsurface plumes or layers of dissolved
hydrocarbons and micro-droplets of liquid oil owing to the dynamics of blowouts
prior to DWH. These results were summarized in a cautionary report by the Ocean
Studies and Marine Boards of the National Research Council (Ocean Studies Board
and Marine Board 2003) suggesting the formation of such plumes in the advent of
a well control accident in the deep sea. In a quintessential understatement, however,
the NRC noted: “The present understanding of deepwater releases suggests they are
much more complicated than those in shallow water.” Indeed.
Experiments conducted prior to DWH examined oil droplet formation, size composition, and impacts of dispersants from turbulent “jets” similar to a severed pipe
scenario. While some theoretical work had been conducted on the behavior and fate
of oil and gas under extreme pressure (Masutani and Adams 2000; Socolofsky and
Adams 2005), research was largely disconnected from the rapid expansion of oil
and gas exploration and production into the ultra-deep (>1500 m; Murawski et al.
2020a). It was not until the C-IMAGE consortium initiated experiments with
methane- saturated (“live”) oil, under relevant pressure and ambient temperature
conditions (e.g., 15 MPa at 4.5 °C in the case of DWH), and simulating pressure
drops as calculated from the actual well casualty (McNutt et al. 2011), that laboratory experiments became sufficiently sophisticated to mirror the likely important
mechanisms leading to the formation of oil droplets small enough to remain
34 Summary of Progress on Major Research Issues: Deep-Sea Oil Spills