Modern Assessment of Natural Hydrocarbon Gas Flux at the Coal Oil Point Seep Field, Santa Barbara, California

TitleModern Assessment of Natural Hydrocarbon Gas Flux at the Coal Oil Point Seep Field, Santa Barbara, California
Publication TypeJournal Article
Year2019
AuthorsPadilla, AM, Loranger, S, Kinnaman, FS, Valentine, DL, Weber, TC
JournalJournal of Geophysical Research: Oceans
Volume124
Pages2472-2484
Date PublishedMarch 7
PublisherJohn Wiley and Sons Ltd.
KeywordsNatural Hydrocarbon; Acoustic Techniques; Gas Flux Measurements; Direct In Situ Measurements; Coal Oil Point Seep Field

The Coal Oil Point seep field is among the most active and studied hydrocarbon seep fields in the world. The water column of the Coal Oil Point seep field was acoustically surveyed from 31 August to 14 September 2016 with a 200‐kHz split‐beam echo sounder to map the distribution of natural hydrocarbons in the region. An in situ direct capture device was used to measure the volumetric gas flux of natural hydrocarbons for three localized seep sites while simultaneously collecting acoustic volume backscatter measurements of the hydrocarbons within the water column. The acoustic volume backscatter was calibrated with the measured volumetric gas flux, and the resulting relationship was used to determine flux over the entire seep field. The estimate of integrated volumetric gas flow rate over a survey area of approximately 4.1 km2 was 23,800 m3/day. The estimates of integrated volumetric gas flow rate and volumetric gas flux were compared to measurements reported in previous studies and were 2 to 7 times smaller than results obtained by Hornafius et al. (1999, https://doi.org/10.1029/1999JC900148), which had a total survey area of 18 km2. However, differences between methodologies limit the ability to assess natural variability in the Coal Oil Point seep field.

DOI10.1029/2018JC014573
Refereed DesignationRefereed