Socolofsky Scott A.
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ArticleFormation dynamics of subsurface hydrocarbon intrusions following the Deepwater Horizon blowout(American Geophysical Union, 2011-05-12) Socolofsky, Scott A. ; Adams, E. Eric ; Sherwood, Christopher R.Hydrocarbons released following the Deepwater Horizon (DH) blowout were found in deep, subsurface horizontal intrusions, yet there has been little discussion about how these intrusions formed. We have combined measured (or estimated) observations from the DH release with empirical relationships developed from previous lab experiments to identify the mechanisms responsible for intrusion formation and to characterize the DH plume. Results indicate that the intrusions originate from a stratification-dominated multiphase plume characterized by multiple subsurface intrusions containing dissolved gas and oil along with small droplets of liquid oil. Unlike earlier lab measurements, where the potential density in ambient water decreased linearly with elevation, at the DH site it varied quadratically. We have modified our method for estimating intrusion elevation under these conditions and the resulting estimates agree with observations that the majority of the hydrocarbons were found between 800 and 1200 m.
ArticleUsing carbon isotope fractionation to constrain the extent of methane dissolution into the water column surrounding a natural hydrocarbon gas seep in the northern Gulf of Mexico(American Geophysical Union, 2018-10-20) Leonte, Mihai ; Wang, Binbin ; Socolofsky, Scott A. ; Mau, Susan ; Breier, John A. ; Kessler, John D.A gas bubble seep located in the northern Gulf of Mexico was investigated over several days to determine whether changes in the stable carbon isotopic ratio of methane can be used as a tracer for methane dissolution through the water column. Gas bubble and water samples were collected at the seafloor and throughout the water column for isotopic ratio analysis of methane. Our results show that changes in methane isotopic ratios are consistent with laboratory experiments that measured the isotopic fractionation from methane dissolution. A Rayleigh isotope model was applied to the isotope data to determine the fraction of methane dissolved at each depth. On average, the fraction of methane dissolved surpasses 90% past an altitude of 400 m above the seafloor. Methane dissolution was also investigated using a modified version of the Texas A&M Oil spill (Outfall) Calculator (TAMOC) where changes in methane isotopic ratios could be calculated. The TAMOC model results show that dissolution depends on depth and bubble size, explaining the spread in measured isotopic ratios during our investigations. Both the Rayleigh and TAMOC models show that methane bubbles quickly dissolve following emission from the seafloor. Together, these results show that it is possible to use measurements of natural methane isotopes to constrain the extent of methane dissolution following seafloor emission.