The world's most spectacular marine hydrocarbon seeps (Coal Oil Point, Santa Barbara Channel, California): Quantification of emissions

Abstract

Abstract. We used 50 kHz sonar data to estimate natural hydrocarbon emission rates from the 18 km 2 marine seep field offshore from Coal Oil Point, Santa Barbara, California. The hydrocarbon gas emission rate is 1.7 + 0.3 x 105 m3d -1 (including gas captured by a subsea seep containment device) and •he associated oil emission rate is 1.6 + 0.2 x 104 Ld -l (100 barrels d-l). The nonmethane hydrocarbon emission rate from the gas seepage is 35 + 7 td -1 and a large source of air pollution in Santa Barbara County. Our estimate is equal to twice the emission rate fi-om all the on-road vehicle traffic in the county.

Climatically driven emissions of hydrocarbons from marine sediments during deglaciation

“…Several lines of evidence support this interpretation. First, as discussed above, petroleum from the Monterey Formation that floats to the surface is readily weathered in oil slicks to the point of becoming negatively buoyant, presumably because of its unusually high resin, asphaltene, and heteroatom content (2,17). Consistent with this observation, hydrocarbon compounds have been detected in sinking particles collected in sediment traps in Santa Barbara Basin (18).…”

“…At modern seeps in SBC, all observed petroleum seepage is closely associated with gas emission; in fact, seepage of methane gas far exceeds that of petroleum (8,9). Although there is significant tar͞hydrocarbon accumulation at localized sites of seepage, surface-ocean oil slicks can extend for Ͼ10 km from their source in the SBC region (2,8,9). Because oil at the sea surface is biologically degraded and volatile components evaporate, a negatively buoyant tar residue forms, which is eventually deposited on beaches and in basin sediments (2).…”

“…Although there is significant tar͞hydrocarbon accumulation at localized sites of seepage, surface-ocean oil slicks can extend for Ͼ10 km from their source in the SBC region (2,8,9). Because oil at the sea surface is biologically degraded and volatile components evaporate, a negatively buoyant tar residue forms, which is eventually deposited on beaches and in basin sediments (2). However, general observations indicate little or no long-term accumulation of tar on these beaches, because the tar is removed from the shoreline within the timescale of tidal cycles.…”

“…However, contributions from ''geologic'' methane sources, including thermogenic hydrocarbons in hydrates and͞or sedimentary reservoirs, remain largely unknown. Quantifying past and present emission rates of methane from marine and terrestrial hydrocarbon sources is critical in understanding the contribution of methane to the atmosphere from these natural sources (2,3).…”

Super fracking

“…6 The northern Santa Barbara Channel, separating the Santa Barbara coast from California's Channel Islands, is one of the largest hydrocarbon seepage areas in the world. 7 Oil and gas leak upward through natural fractures and tectonic faults in the Monterey shale. The most intense area of natural seepage is about 15 km west of Santa Barbara at the Coal Oil Point seep field, where the resulting oil slicks can be as much as 10 km long.…”