BP / Gulf Oil Spill – Radar and MODIS, July 19, 2010

The cap on BP’s infamous Macondo oil well in the Gulf of Mexico is still shut, but small leaks have reportedly appeared on the seafloor around the well site. This is troubling because it suggests that the well casing is damaged and leaking somewhere below the seafloor. According to Coast Guard Admiral Thad Allen, one of those leaks is actually coming from an older abandoned well nearby – he goes so far as to say:

“it’s not unusual to have seepage around the old wells”

The AP recently did a story (featuring SkyTruth, among others) on the fact that there are 27,000 abandoned wells in the Gulf, and that abandoned wells on land leak so frequently that there is an ongoing need to re-plug them. I guess Admiral Allen confirms what the AP suspected – that this is also a problem with offshore wells. Who knew? Now we all do.

BTW, we wish folks would only use the term “seepage” when talking about natural oil and gas seeps on the seafloor, not human-caused leaks.

MODIS / Aqua and CSK radar satellite images taken on July 19 show oil slicks and sheen spanning about 7,868 square miles. This is almost twice as large as the area of slicks observed on satellite imagery from July 14, but still a lot smaller than it’s been on previous imagery.

MODIS / Aqua satellite image from July 19, 2010

Oil slicks and sheen appear through a complicated assortment of clouds and haze on the MODIS image, taken at about 2pm local time on July 19, 2010. An area of anomalous ocean color (dashed line marks its eastern edge) appears to mirror the eastern edge of the area covered by surface oil slicks. This may be an indication of changed water chemistry in the area affected by the spill – possibly due to oxygen depletion as a result of the elevated levels of methane (natural gas) dissolved in the water.

The edge of the ocean-color anomaly seen on the MODIS / Aqua image is shown for reference on the CSK radar images taken a few hours later that same day:

COSMO-SkyMed radar satellite images (black-and-white) taken July 19, 2010, superimposed on MODIS image from the same day (color). CSK images courtesy CSTARS.

BP / Gulf Oil Spill – Stopped (For Good?)

Screen capture from Skandi ROV2 live spill cam, 12:42am EDT, July 16, 2010

Finally, after 87 days, the leak from BP’s Macondo well in the Gulf of Mexico is fully stopped. All the valves on the new sealing cap have been closed and an “integrity test” is being conducted on the well. If the pressure steadily increases in the well, that’s a good thing: it would mean there are no leaks in the wellpipe and casing below the seafloor. In that case BP will keep the valves closed, effectively shutting off this catastrophic spill. If the pressure doesn’t build in the well it could mean there are leaks below the seafloor, and BP will re-open some of the valves and the spill will resume. In any event, the only permanent solution is a successful relief well that fills the damaged well with cement.

MODIS / Aqua satellite image, July 14, 2010

This MODIS / Aqua satellite image, taken on July 14, shows that the area of oil slicks and sheen appears greatly reduced: slicks cover approximately 3,786 square miles (9,805 km2) on this image. Radar satellite images taken on July 11 and July 12 confirm this smaller slick area.

Persistent, moderately strong winds over the past few days (ranging from 7-20 miles per hour) may have dispersed thinner portions of the slick over much of the region.

BP / Gulf Oil Spill – Radar Comes Through Again

This satellite radar image taken by Envisat’s ASAR sensor at 10:44pm local time on July 7 shows a large patch of oil extending north from the site of the leaking Macondo well, and an area of small slicks along the Mississippi shoreline:

Envisat ASAR radar image (black-and-white) taken July 7, 2010. Image courtesy of CSTARS.

A large dark area extending from west of Mobile Bay to beyond Panama City may include patchy oil slicks and sheen, as seen in this area on previous days. But it is also an area of calm winds; the surface wind speed was measured at Buoy 42012 at 1 meter per second, gusting to 2 m/s, at the time this image was acquired. That’s on the low-end threshold for oil slick detection with radar imagery.

This infrared GOES weather satellite image taken within minutes of the radar image shows the skies are mostly clear in the area, with no sign of rainfall:

BP / Gulf Oil Spill – July 4th Weekend

With oil continuing to billow into the Gulf of Mexico from BP’s failed Macondo well, the holiday weekend brought little cause for celebration, and no break for the folks working hard to clean up the oil coming ashore and to plug the leaking well. Oil was reported for the first time in Lake Pontchartrain, and the discovery of tar balls on some Texas beaches means this spill is now directly impacting all of the Gulf states.

A RADARSAT-2 satellite image taken July 2 shows oil slick and sheen still spread across a large area of the Gulf in the wake of Hurricane Alex, which brought large waves and strong gusty winds to the area last week:

RADARSAT-2 satellite image taken July 2, 2010. Image courtesy of CSTARS.

MODIS satellite images acquired on July 3 and July 4, while impaired once again by clouds, showed portions of the oil slick in a few areas. The July 3 image shows patches of slick along the Louisiana coast reaching west beyond Vermilion Bay:

MODIS/Aqua satellite image acquired on July 3

It also shows a neat little circular pattern formed by a cluster of natural oil and gas seeps; the small slicks that form at the ocean surface above these deepwater seeps appear to be caught up in a clockwise gyre (a rotating surface current).See all the images in our Deepwater Horizon Oil Spill gallery.

BP / Gulf Spill – NOAA Forecasts Long-Term Threat To Coasts

NOAA has just released the results of modeling to analyze the long term threat posed by the ongoing oil spill to coastlines throughout the Gulf, Florida Keys, and East coast shorelines:

NOAA forecast showing likelihood of coastline being threatened by oil over the long term by BP spill

Their model shows the probability that oil will approach within 20 miles of the shoreline. It assumes the net daily spill rate is 1.4 million gallons (33,000 barrels) per day for 90 days beginning April 22, when the Deepwater Horizon rig sank and the fire was extinguished. We’re at Day 76 right now, so this assumes a relief well plugs the leak within the next 2 weeks. They are steadily closing in on the target depth of about 13,000′ below the seafloor, so we’re hopeful BP will succeed ahead of their stated mid-August goal.

The model is based on historical wind and ocean current information, and accounts for the natural breakdown of oil at sea. It doesn’t account for the movement and ultimate fate of oil beneath the water’s surface, because we just don’t know enough about that yet. Read all about the model and the assumptions and data used to run it. You can also see other maps, graphics, animations and movies showing the model results for individual scenarios.