136
oil- water partition measurements fail to reflect changes in gas concentrations in live
oils, which were addressed by using an in-house constructed device, capable of
measuring the partitioning behavior of BTEX compounds between gas-charged live
oil and cold high-pressure water.
The partition ratios of BTEX compounds between oil and water decrease substantially as the plume migrates to lower pressure values near the sea surface
(from 15 to 2 MPa) due to the decreasing concentration of dissolved methane gas
in oil at lower pressures. The partition ratios of BTEX compounds increase proportionally with an increase in alkylation and with decrease in temperature over
the range of 4–20 °C, but the decrease in pressure dominates the net behavior as
oils migrate to shallower depths. These observed effects of pressure and temperature act together to increase the equilibrium concentration of BTEX compounds
in the water phase as the plume migrates toward the surface. However, as the
plume loses BTEX compounds during its upward migration, the actual behavior
becomes much more complex. The effects of pressure and temperature are similar
when comparing systems with and without dispersants. The addition of dispersants, however, adds an additional effect of increasing the extent of organics partitioning into the water, especially at equilibrium under lower-pressure
conditions.
The results of this study will help improve both near-field and far-field distribution modeling of the environmental fate of toxic crude oil components, by predicting component migration pathways from potential oil spills, as well as plume
behavior assessments from deep-water blowouts. Overall, these models will help to
understand and predict the impact of oil spills on marine ecosystems and to improve
oil spill response strategies.
For additional insights, it will be useful to use different oil types to assess the
impact of changing oil chemistry on the partitioning behavior of xenobiotics through
the hypothetical water column. This study was conducted to measure the partition
ratios at PT conditions for ~1500 m of water depth, as per the Macondo setting.
However, with planned deeper future drilling operations in the Gulf of Mexico at
double that depth (~3000 m), there is also a need to expand the data set to higher
pressures, either experimentally or via experimentally calibrated models. The information gathered from these deeper well models, when combined with the findings
of this report, could be used to ensure that safer and more environmentally friendly,
mitigation strategies are undertaken, should an incident similar to the Macondo
blowout occur.
Acknowledgments This research was made possible in part by a grant from The Gulf of Mexico
Research Initiative/C-IMAGE II and in part by the Canada Foundation for Innovation (CFI), the
Natural Sciences and Engineering Research Council of Canada (NSERC) and Canada Research
Chairs (CRC), PRG, and the University of Calgary.
A. Jaggi et al.
oil- water partition measurements fail to reflect changes in gas concentrations in live
oils, which were addressed by using an in-house constructed device, capable of
measuring the partitioning behavior of BTEX compounds between gas-charged live
oil and cold high-pressure water.
The partition ratios of BTEX compounds between oil and water decrease substantially as the plume migrates to lower pressure values near the sea surface
(from 15 to 2 MPa) due to the decreasing concentration of dissolved methane gas
in oil at lower pressures. The partition ratios of BTEX compounds increase proportionally with an increase in alkylation and with decrease in temperature over
the range of 4–20 °C, but the decrease in pressure dominates the net behavior as
oils migrate to shallower depths. These observed effects of pressure and temperature act together to increase the equilibrium concentration of BTEX compounds
in the water phase as the plume migrates toward the surface. However, as the
plume loses BTEX compounds during its upward migration, the actual behavior
becomes much more complex. The effects of pressure and temperature are similar
when comparing systems with and without dispersants. The addition of dispersants, however, adds an additional effect of increasing the extent of organics partitioning into the water, especially at equilibrium under lower-pressure
conditions.
The results of this study will help improve both near-field and far-field distribution modeling of the environmental fate of toxic crude oil components, by predicting component migration pathways from potential oil spills, as well as plume
behavior assessments from deep-water blowouts. Overall, these models will help to
understand and predict the impact of oil spills on marine ecosystems and to improve
oil spill response strategies.
For additional insights, it will be useful to use different oil types to assess the
impact of changing oil chemistry on the partitioning behavior of xenobiotics through
the hypothetical water column. This study was conducted to measure the partition
ratios at PT conditions for ~1500 m of water depth, as per the Macondo setting.
However, with planned deeper future drilling operations in the Gulf of Mexico at
double that depth (~3000 m), there is also a need to expand the data set to higher
pressures, either experimentally or via experimentally calibrated models. The information gathered from these deeper well models, when combined with the findings
of this report, could be used to ensure that safer and more environmentally friendly,
mitigation strategies are undertaken, should an incident similar to the Macondo
blowout occur.
Acknowledgments This research was made possible in part by a grant from The Gulf of Mexico
Research Initiative/C-IMAGE II and in part by the Canada Foundation for Innovation (CFI), the
Natural Sciences and Engineering Research Council of Canada (NSERC) and Canada Research
Chairs (CRC), PRG, and the University of Calgary.
A. Jaggi et al.