Factors Affecting Marine Hydrocarbon Emissions in an Area of Natural Seeps and Abandoned Oil Wells - Summerland, California

Abstract

A video-monitored oil-seep capture tent and an intertidal seep tank were developed and deployed to quantify emissions in shallow (5-m) nearshore waters and at an intertidal location at Summerland Beach, California. At two sites, where bubbles appeared clear, gas to oil ratios were 105:1; at a site where bubbles were dark, gas to oil ratio was 8.4:1. Nearshore oil emissions were conservatively estimated at 0.8 L dy’1. The size distribution of oily bubbles sharply peaked at 1500 µm, and the gas to oil ratio varied between bubbles. Oil affected the bubble's buoyancy and hydrodynamics. Time series of seabed emissions showed oil was mostly released in pulses. Several mechanisms that may cause variability in oil emissions were proposed. Intertidal oil emission were estimated a 12 L dy−1. Also, beach surveys showed less than trace amounts of beached oil and no oiled fauna over a 19-month period.

A Synthesis Review of Emissions and Fates for the Coal Oil Point Marine Hydrocarbon Seep Field and California Marine Seepage

“…As oil droplets rise, they lose lighter components (including gases) to the water column through dissolution [60]. Even liquid oil droplets may form bubbles due to effervescence as they rise and hydrostatic pressure decreases [152].…”

Tracking an oil slick from multiple natural sources, Coal Oil Point, California

“…This may be due to oil trapping in the kelp where it could have degraded for longer, or mixed with tar trapped in the kelp. Tar trapping in kelp has been proposed to affect tar distributions on the beaches off COP (Leifer et al, 2004c) and oil slicks on beaches off Summerland, CA (Leifer et al, 2004b). Also shown is a chromatogram for the Seep Tent Seep oil slick (Fig.…”

Dynamics of Live Oil Droplets and Natural Gas Bubbles in Deep Water

“…Comparison of TAMOC predictions with laboratory observations reported by Pesch et al23,37 for live and dead oil droplets (Experiments[1][2][3][4][5][6][7][8][9][10][11][12]. Also shown are model values when assuming suppressed aqueous dissolution of methane.…”

“…Whereas the physical behavior of gas bubbles are well-documented, 6,[11][12][13][14][15][16][17][18][19][20] few direct observations have revealed the chemical and thermodynamic behavior of live liquid petroleum under shallow or deep-water conditions in either the field or the laboratory. [4][5][6][21][22][23][24][25] Limited field observations have been made on composition, dynamic behavior, ebullition, and oil-to-gas phase transfer, [4][5][6]25 and laboratory observations have been made on methane-saturated live oil with and High-pressure laboratory measurements reported by Pesch et al 23 provide the first direct, quantitative observations of free rising live oil droplets undergoing the coupled physical and chemical processes that are relevant in deep water. In repeated experiments, these researchers studied an oil droplet that was initially saturated with methane under high pressure conditions and then placed within a counter-current flow channel filled with artificial seawater at high pressure (151 bar).…”

“…Petroleum fluids comprising gaseous and liquid phases may enter deep water through natural seeps, − small-scale leaks during industry operations, leaking abandoned wells, , or major accidents such as the Deepwater Horizon disaster . During such events, the coupled chemical and physical dynamics of the released gaseous and live liquid petroleum phases largely determine the trajectories and fates of these fluids in the environment.…”