Compositional changes in natural gas bubble plumes: observations from the Coal Oil Point marine hydrocarbon seep field

Abstract

Detailed measurements of bubble composition, dissolved gas concentrations, and plume dynamics were conducted during a 9-month period at a very intense, shallow (22-m water depth) marine hydrocarbon seep in the Santa Barbara Channel, California. Methane, carbon dioxide, and heavier hydrocarbons were lost from rising seep bubbles, while nitrogen and oxygen were gained. Within the rising seawater bubble plume, dissolved methane concentrations were more than 4 orders of magnitude greater than atmospheric equilibrium concentrations. Strong upwelling flows were observed and bubble-rise times were $40 s, demonstrating the rapid exchange of gases within the bubble plume.

Bubble Transport Mechanism: Indications for a gas bubble-mediated inoculation of benthic methanotrophs into the water column

“…The Santa Barbara basin (California, USA) contains one of the world's largest and best investigated hydrocarbon seep fields, the Coal Oil Point seep field (Allen et al, 1970;Clark et al, 2003;Hornafius et al, 1999; Fig. 1).…”

Gaseous emission rates from natural petroleum seeps in the Upper Ojai Valley, California

“…Etiope and Klusman (2002) ( Washburn et al, 2005), two orders of magnitude greater than the largest valley seep and in agreement with Etiope and Klusman (2002) classification. The sea-floor composition of the offshore seeps differs from the Ojai seeps in that they contain higher fractions of C 1 -C 4 hydrocarbons and less CO 2 (Clark et al, 2003). Because the ocean is able to absorb most of the sea-floor CO 2 emissions, the atmospheric flux of CO 2 from these two fields is approximately the same.…”

High pressure autothermal reforming in low oxygen environments

“…Other prominent seeps are found in the Caspian Sea [26] and the Gulf of Mexico [27]. Analysis of gas samples from the Shane Seep taken over a period of several months 6 showed a composition averaging 83.4% Cf4, 11.7% C02, 1.8% N2, and 0.28% 02, with the balance being classified as non methane hydrocarbons [13]. These seeps provide a largely untapped supply of relatively pure methane that could be potentially harvested.…”

“…The oxygen concentration in researched gas vents is less than I % [13,48]. This means oxygen isn't present in high enough concentrations to sustain the ATR reforming reactions and therefore oxygen would need to be stored onboard the system.…”