Monitoring of natural oil seepage in the Lower Congo Basin using SAR observations

Jatiault, Romain; Dhont, Damien; Loncke, Lies; Dubucq, Dominique

doi:10.1016/j.rse.2017.01.031

Cited by 38 publications

(36 citation statements)

References 66 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Proximal areas from the shelf are probably affected by more consistent current variability between the BCC (Hopkins et al, 2013) and the AC (Hardman-Mountford et al, 2003), but also can be affected by a "Venturi effect" that increases the velocity of water masses towards the shelf. The enhancement of the current velocity in shallower areas of the LCB (Santos et al, 2012;Kopte et al, 2017) is probably responsible for the greater deflection values observed during long-term monitoring (Jatiault et al, 2017).…”

Section: Horizontal Deflection Compared To the Water Depthmentioning

confidence: 95%

“…The study area is located offshore Angola in the Lower Congo Basin (LCB) ( Fig. 1), in water depths ranging from 1200 to 2700 m. The LCB deep-water province corresponds to one of the most important natural oil seep systems in the world, where 4380 m 3 of oil is expelled each year towards the sea surface (Jatiault et al, 2017). In addition, extensive oil and gas exploration activities in the LCB during the last decades have provided a large volume of geophysical data, both at the seafloor and in the water column.…”

Section: Regional Settingsmentioning

confidence: 99%

“…The presence of oil slicks strongly affects the seasurface roughness and significantly reduces the amount of backscattered energy to the satellite, accounting for the Fresnel specular reflection. Sea surface covered by oil seepage appears as low radiometric areas on SAR images (e.g., Espedal and Wahl, 1999;Johannessen et al, 2000;Espedal and Johannessen, 2000;Williams and Lawrence, 2002;Zatyagalova et al, 2007;Ivanov et al, 2007;Garcia-Pineda et al, 2010;Körber et al, 2014;Jatiault et al, 2017).…”

Section: Remote Sensing Inventory Of Natural Oil Seep Sitesmentioning

confidence: 99%

“…We mapped about 3000 seepage slicks using local radiometry anomalies identified from the analysis of overlapping SAR scenes that were reliably associated with a hundred of recurrent seep sites ( Fig. 2; Jatiault et al, 2017). The seeping province was located about 150 km offshore Angola at water depths ranging from 1200 to 2700 m. The detectable proximal edge of recurrent oil slicks (i.e.…”

Section: Remote Sensing Inventory Of Natural Oil Seep Sitesmentioning

confidence: 99%

“…Natural hydrocarbon seeps occur along most continental margins (Wilson et al, 1973;Levy and Ehrhardt, 1981;MacLean et al, 1981;Becker and Manen, 1988;Kvenvolden and Cooper, 2003;Zatyagalova et al, 2007;Jauer and Budkewitsch, 2010;Körber et al, 2014;Suresh, 2015;Jatiault et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Deflection of natural oil droplets through the water column in deep-water environments: The case of the Lower Congo Basin

Jatiault

Dhont

Loncke

et al. 2018

Deep Sea Research Part I: Oceanographic Research Papers

Self Cite

View full text Add to dashboard Cite

A B S T R A C TNumerous recurrent seep sites were identified in the deep-water environment of the Lower Congo Basin from the analysis of an extensive dataset of satellite-based synthetic-aperture radar images. The integration of current data was used to link natural oil slicks with active seep-related seafloor features. Acoustic Doppler current profiler measurements across the water column provided an efficient means to evaluate the horizontal deflection of oil droplets rising through the water column. Eulerian propagation model based on a range of potential ascension velocities helped to approximate the path for rising oil plume through the water column using two complementary methods. The first method consisted in simulating the reversed trajectory of oil droplets between sea-surface oil slick locations observed during current measurements and seep-related seafloor features while considering a range of ascension velocities. The second method compared the spatial spreading of natural oil slicks from 21 years of satellite monitoring observations for water depths ranging from 1200 to 2700 m against the modeled deflections during the current measurement period. The mapped oil slick origins are restricted to a 2.5 km radius circle from associated seep-related seafloor features. The two methods converge towards a range of ascension velocities for oil droplets through the water column, estimated between 3 and 8 cm s −1 . The low deflection values validate that the sub-vertical projection of the average surface area of oil slicks at the sea surface can be used to identify the origin of expelled hydrocarbon from the seafloor, which expresses as specific seafloor disturbances (i.e. pockmarks or mounds) known to expel fluids. standing the hydrocarbon plumbing system (Serié et al., 2016). Pockmarks, which are local depressions on the seafloor associated with contemporary focused fluid flow (e.g. King and MacLean, 1970;Hovland and Judd, 1988), are widely recognized as the seafloor outlet of expelled fluids. Even if hydrocarbon migration across the water

show abstract

Section: Horizontal Deflection Compared To the Water Depthmentioning

confidence: 95%

Section: Regional Settingsmentioning

confidence: 99%

Section: Remote Sensing Inventory Of Natural Oil Seep Sitesmentioning

confidence: 99%

Section: Remote Sensing Inventory Of Natural Oil Seep Sitesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Deflection of natural oil droplets through the water column in deep-water environments: The case of the Lower Congo Basin

Jatiault

Dhont

Loncke

et al. 2018

Deep Sea Research Part I: Oceanographic Research Papers

Self Cite

View full text Add to dashboard Cite

show abstract

Natural Escapes of Oil in Sedimentary Basins: Space‐borne Recognition and Pairing with Seafloor and Sub‐seafloor Features

Jatiault¹

2020

Remote Detection and Maritime Pollution

View full text Add to dashboard Cite

Physical Controls on the Creation and Persistence of Natural Marine-Seepage Slicks

Meurer

MacDonald

Asl

et al. 2022

Preprint

View full text Add to dashboard Cite

Physical processes involved in the ascent of naturally seeped oil from the seafloor and its persistence as a slick are considered. Simplified, physics-based models are developed, drawing in part from the extensive literature concerned with anthropogenic releases of oil at sea. The first model calculates the ascent of oil droplets or oil-coated gas bubbles as they ascend to the sea surface from the seep source. The second model calculates slick longevity as a function of the effect of wind-driven breaking waves. Both models have simplified inputs and algorithms making them suitable for Monte Carlo-type analysis. Using the oil ascent model, we find that slicks from shallower seeps are offset farther relative to their water depth than those from deeper sources. The slick longevity model reveals four growth modes for seepage slicks: persistent (low wind speeds), ephemeral (high wind speeds), reset (all slicks are cleared from an area by high wind speeds), and aging (slick growth after a reset). A year's worth of modeled winds from the Gulf of Mexico indicate average slick ages of ˜12 hours. Taking account of the expected oil release duration implied by slick recurrences yields average slick longevities for high recurrence seeps of ˜6.5 hours and ˜5 hours for low recurrence seeps. Seep flux estimates that include the length of individual slicks and the constraints of local currents and wind implicitly take into account the impact of wind-speed history. Those that assume a slick age should be re-evaluated in light of the current findings.

show abstract

Monitoring of natural oil seepage in the Lower Congo Basin using SAR observations

Cited by 38 publications

References 66 publications

Deflection of natural oil droplets through the water column in deep-water environments: The case of the Lower Congo Basin

Deflection of natural oil droplets through the water column in deep-water environments: The case of the Lower Congo Basin

Natural Escapes of Oil in Sedimentary Basins: Space‐borne Recognition and Pairing with Seafloor and Sub‐seafloor Features

Physical Controls on the Creation and Persistence of Natural Marine-Seepage Slicks

Contact Info

Product

Resources

About