Long-term acoustic monitoring and tracking of natural hydrocarbon seeps from an offshore oil platform in the Coal Oil Point seep field

Abstract

The Coal Oil Point (COP) seep field, located offshore of Santa Barbara, California, is known for its prolific, natural hydrocarbon seepage activity. The COP seep field has been active for decades and previous research indicates both spatial and temporal variability in seep activity across the area. An offshore oil platform within the COP seep field, known as Platform Holly, has extracted oil and gas in the area since the late 1960s, which has been linked to a reduction in natural seep activity. In recent years, Platform Holly has been decommissioned, and anecdotal observations indicate a subsequent resurgence in natural seep activity in the vicinity. In early September 2019, a Simrad ES200 split-beam echosounder was mounted to one of the cross-members of the platform to collect acoustic measurements of the seepage activity west of the platform. This long-term time series of acoustic measurements will provide insight on the spatial and temporal variability of seepage activity in the region and how said variability is affected by external physical processes such as atmospheric pressure, currents, and tides.