Twitter Not Working (For Us, Anyway) - Oil Spill Updates

For some reason we've been unable to tweet for more than 24 hours now. We're entering severe withdrawal, but we can still give you this update (in waaay more than 140 characters):

• Michigan pipeline spill / Kalamazoo River. The EPA estimates this spill exceeded 1 million gallons, and has now traveled more than 35 miles downriver from the point of origin since the leak began on July 26. Michigan governor Granholm is urging more aggressive response to keep this spill from reaching Lake Michigan.

• Louisiana blowout and spill / Barataria Bay - Bayou St. Denis. The Coast Guard is saying it will take at least 10-12 more days to plug the abandoned well that has been spouting a 100' geyser of oil and gas out of water since it was hit by a barge on July 27.

• Dalian, China pipeline explosion and spill. Greenpeace claims this spill is much larger than reported by the Chinese government - possibly 60 times bigger, based on revelations that Chinese workers purposefully dumped oil into the ocean so it wouldn't feed the raging inferno and cause more destruction of storage facilities onshore. Greenpeace also claims a full oil storage tank capable of holding about 28 million gallons was destroyed during the fire, possibly releasing its contents into the water as well.

• BP / Deepwater Horizon spill, Gulf of Mexico. The containment cap is holding, remains shut, and no new oil has leaked into the Gulf from the Macondo well since July 15. Although thick, "skimmable" oil slicks have reportedly become hard to find floating on the Gulf's surface, questions remain about how much oil continues to linger beneath the surface and out of sight. Recent satellite images show what we assume is mostly thin sheen still present across a large area. The much-anticipated "static kill" procedure to pump drilling mud directly into the well through the cap is now planned for Tuesday, with the relief well in position to begin intercepting the Macondo well by August 11 or 12. Successful execution of the "bottom kill" procedure - pumping more mud, then cement, into the well via the relief well - could take an additional three weeks.

Today's MODIS / Aqua satellite image of the Gulf seems to have good illumination conditions for showing oil slicks and sheen east of the Delta. We don't see much indication of the widespread sheen that was present on the July 28 imagery, although a large part of that oily-looking area is south and slightly west of the Delta and obscured by clouds on today's image. Stay tuned, this continues to be a very dynamic event.

BP / Gulf Oil Spill - Curb Your Enthusiasm, Part 2

Yesterday's MODIS and RADARSAT images show something we didn't expect: slicks and sheen spanning nearly 12,000 square miles. Based on other reports, and the recent trend on satellite images indicating steady dissipation of the surface oil slick, we are optimistically assuming that nearly all of this is very thin sheen.

Speculation: winds from Bonnie obliterated most of the thin sheen throughout the area; but since then, sheen has had time to "reassemble" into observable layers that noticeably affect the sunglint on MODIS images, and the backscatter on radar, but may not look like much to folks out in the Gulf on vessels or in low-flying aircraft. That's our theory at this point. Chime in if you have other thoughts about what we're seeing on these images:

MODIS/Aqua satellite image, July 28, 2010

The MODIS / Aqua satellite image above, taken at 2 pm Central time on July 28, shows oil slicks and sheen (encircled with orange line) that we think are likely attributable to the BP / Deepwater Horizon oil spill, spread out across 11,832 square miles (30,644 km2) in the Gulf of Mexico. We've marked the eastern edge of a persistent ocean-color anomaly with a dashed line; this anomaly may simply be related to the Mississippi River discharge, or could indicate an area where ocean chemistry has been affected by oil, dispersant, and/or dissolved methane from the spill and cleanup response. Three small slicks attributable to natural oil and gas seeps are also marked.

RADARSAT-2 satellite image (black-and-white) taken July 28, 2010. RSAT-2 data courtesy CSTARS.

We overlayed the RADARSAT-2 image (black-and-white) taken at 6:48 pm Central time on the MODIS/Aqua image taken earlier that same day. The large dark area on the radar image is probably oil slick and sheen from the BP oil spill: wind conditions throughout the area were ideal for slick and sheen detection on radar satellite imagery, ranging from 2 to 8 meters per second with minimal gusts. Weather satellite images taken at about the same time showed few clouds in the area and very low chance of any rain in the vicinity.

More &!#@% Oil Spills - Pipelines, Abandoned Wells

Fountain of natural gas and crude oil from well blowout along Louisiana coast this week. Source: Associated Press.

Ugh - more oil spill news:

• An estimated 800,000 gallons of crude oil gushed from a failed pipeline operated by a Canadian company, inundating a creek and flowing into the Kalamazoo River in Michigan. The leak began on Monday, and was stopped on Tuesday. Containment and cleanup operations are underway, but so far a 16-mile stretch of the Kalamazoo has been fouled by oil. The cause of the pipline failure has not yet been reported.
  

• On Tuesday, a tug boat collided with an "orphaned" oil well off the Louisiana coast near Bayou St. Dennis, between Lafitte and Grand Isle, leading to a blowout of that well that is still shooting a fountain of light crude propelled by natural gas up out of the water and 100 feet into the air. The boat sheared off the wellhead and control valves on the well, located in water only about 6 feet deep. Hopefully it will be controlled and permanently plugged today.
  

Obviously this well had not been properly plugged with cement to prevent such an occurance. An "orphan" is a well that the operator simply (and illegally) walks away from. In this case they walked away in 2008, and the state declared the well abandoned. This well has been a ticking time bomb ever since.

And by the way, there are 27,000 abandoned wells in the Gulf of Mexico, including 3,500 wells that have been "temporarily" abandoned - some for years - without being permanently plugged.
Maybe it's time to fix this.

BP / Gulf Oil Spill - Curb Your Enthusiasm

We're as relieved as anybody to see that the massive months-long oil slick from the BP / Deepwater Horizon blowout is finally breaking up, but it's way too early to declare victory:

• The deadly and still-dangerous Macondo well is not yet permanently plugged.
• Oil is still lingering out of sight, beneath the water's surface, a few inches deep in some places and thousands of feet down in others. Nobody know how much oil remains in the water column, how long that oil will linger, where it will end up, and what the impacts will be on the Gulf ecosystem.
• Our preliminary analysis shows oil cumulatively covered 68,000 square miles of Gulf waters. Oil reportedly came ashore on hundreds of miles of beaches and wetlands. Oil is deeply embedded in marshes, and buried under the sand on beaches. This oil could linger and have toxic impacts for years, possibly decades.
  

As NOAA Administrator Jane Lubchenko says in today's New York Times,

Less oil on the surface does not mean that there isn’t oil beneath the surface, however, or that our beaches and marshes are not still at risk. We are extremely concerned about the short-term and long-term impacts to the gulf ecosystem.

At SkyTruth, we'll keep looking at the Gulf. If funding allows, we'll use satellite imagery and other remote-sensing techniques to track the future health of marsh grasses and coastal ecosystems where oil made landfall.

BP / Gulf Oil Spill - 68,000 Square Miles of Direct Impact

Fingers crossed: it looks like the cap on BP's Macondo well will hold until the relief well intercepts and permanently plugs it, and no more oil from this blowout will enter the Gulf.

So here's a map showing the cumulative oil slick footprint for the BP / Deepwater Horizon oil spill, created by overlaying all of the oil slicks and sheen mapped by SkyTruth on satellite images taken between April 25 and July 16, 2010, blogged here, and published in our gallery.

Cumulatively, the surface oil slicks and sheen observed on these satellite images directly impacted 68,000 square miles of ocean - as big as the state of Oklahoma:

Map showing cumulative oil slick footprint from BP / Deepwater Horizon oil spill, based on satellite images taken between April 25 and July 16, 2010

BP / Gulf Oil Spill - The Slick Is Dissipating

At long, long last.

Radarsat images taken yesterday (July 26) show the oil slick is steadily dissipating. The failed Macondo well has been tightly sealed since July 15, so no new oil has been entering the Gulf for over a week. Oil floating at the ocean's surface has a limited lifespan - it's been collected and destroyed by skimming, booms, chemical dispersants, evaporation, photolysis, biodegradation - and took a beating from wind and waves when tropical depression Bonnie blew through over the weekend. If the well stays plugged until the static-kill and bottom-kill efforts permanently plug it with cement, then the remaining fragments of slick should disappear within days.

The big question: what's the fate and impact of the oil we can't see with satellite images? Oil now buried on Gulf coast beaches, embedded in marshes, and remaining dispersed underneath the water's surface or lying on the seafloor? It will take diligent, systematic research to find the answers. We need to make sure that this research actually gets funded, conducted and published, and not sidetracked by litigation and confidentiality.

Here's the July 26 imagery without SkyTruth's analysis. Wind conditions (ranging from 3-6 meters per second) were nearly ideal for detecting oil slicks on radar imagery. Scattered dark patches of slick and sheen are spread across a wide area, but it appears that the oil slick created by the Macondo well blowout is steadily dissipating, and no new oil can be found around the well site:

RADARSAT images taken July 26, 2010, without analysis. Images courtesy CSTARS.

And here's the version with our analysis of BP-related oil slicks and sheen, delineated in orange:

RADARSAT images taken July 26, 2010, with SkyTruth analysis. Images courtesy CSTARS.

BP / Gulf Oil Spill - What Did Bonnie Do?

The center of Bonnie's circulation appears close to the Macondo well site on a CSK radar satellite image taken July 24. CSK and MODIS satellite images the next day, July 25, show remnants of the BP oil slick scattered around the Mississippi Delta. No new oil is seen around the well site; it's been tightly capped since July 15.

COSMO-SkyMed radar satellite image showing center of circulation of tropical depression Bonnie, July 24, 2010. CSK-1 image courtesy CSTARS. Backdrop (color) is MODIS/Aqua image from earlier the same day.

The center of circulation for tropical depression Bonnie was located about 15 miles (24 km) south-southeast of the Macondo well site when this CSK-1 radar satellite image (black-and-white) was taken, at 6:44 pm local time. Weather station 42364, on the Ram-Powell oil platform about 27 miles (43 km) northeast of the Macondo well, recorded sustained wind speed of 22 mph (10 m/s) at that time. Station 42887 on the Thunder Horse oil platform about 39 miles (63 km) south of the well recorded winds at 11 mph (5 m/s).

Radar images show the "roughness" of the ocean's surface, revealing the pattern of Bonnie's counterclockwise-circulating winds. The strongest winds are generally in the northeast quadrant of cyclones in the northern hemisphere. This is reflected by the overall gray tone in the radar image: the area of stronger winds north and east of the storm's center is brighter than the area to the south and west.

Two distinct storm bands are also apparent; these are lines of strong thunderstorms with gusty winds. A narrow line of oil slick is also visible - possibly related to the BP / Deepwater Horizon spill, although we think most of the slick and sheen from that spill is obscured on the radar image by the strong wind conditions.

COSMO-SkyMed radar and MODIS/Terra satellite images taken July 25, 2010, showing remnants of BP oil slick. CSK-1 image courtesy CSTARS.

CSK radar and MODIS / Terra satellite images taken on July 25, 2010, show the effects of tropical depression Bonnie's passage on the oil slicks and sheen from the spill. No new oil is seen in the immediate vicinity of the well. But remnants of the oil slick are visible around the Mississippi Delta.

The MODIS image also shows dozens of small oil slicks from natural oil and gas seeps. These seeps appear unusually active, possibly due to seafloor disturbance caused by Bonnie. A bright area of slicks or sheen between the spill-related oil slicks (orange line) and the area of active seeps (dashed red line) could be where oil from both sources is mingling.

See all of SkyTruth's images related to the BP / Deepwater Horizon spill in our gallery.

BP / Gulf Spill - Buh Bye, Bonnie

More good news for the Gulf: Bonnie was a bust. She blew over the BP / Deepwater Horizon spill site Saturday morning as a rapidly weakening tropical depression. NOAA weather buoys and stations in the eastern Gulf barely registered her passing, with sustained winds at the leak site only briefly exceeding 14 meters per second (about 31 mph). Fellow weather-geeks, check out the data from Station 42364 (located on the Ram-Powell oil platform operated by Shell) and Station 42376 (on the Marlin platform operated by BP).

BP / Gulf Oil Spill - Here Comes Bonnie

3-day forecast track for Tropical Depression Bonnie, expected to strengthen over the weekend

The Bad News: Tropical Depression Bonnie is making a beeline through the eastern Gulf of Mexico, heading right for the Macondo well site. According to the National Weather Service, Bonnie should cross over the site on Saturday afternoon, strengthened by her trip over warm Gulf waters to a tropical storm with sustained winds over 40 miles per hour. Crews are being evacuated from the area, and progress on the relief wells has been brought to a halt.

GOES weather satellite image of Bonnie, taken at 5pm Central time on July 23, 2010

The Good News: The cap on the Macondo well has been shut tight for several days, and we no longer see signs of fresh oil upwelling around the site of the failed well. We have also noticed a significant reduction in the surface oil slicks in the Gulf since early July. Although we don't know how much oil is lingering out of sight beneath the surface, we hope this means that far less oil is available to be thrown up onto the beaches and into the wetlands when Bonnie comes through.

On June 29, when Tropical Storm Alex was moving past in the southern Gulf, the area of slicks on satellite images spanned 19,000 square miles; the MODIS / Aqua image below, taken on July 21, shows a fragmented area of slicks and sheen covering 5,476 square miles:

MODIS / Aqua satellite image taken July 21, 2010

However, the large area of anomalous ocean color noted on a July 19 MODIS image is even more obvious. It shares spectral characteristics with the sediment-laden plume emerging from the Mississippi River, but it may also indicate 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 eastern edge of this anomaly is marked with a dashed brown line.

See all of SkyTruth's images of the BP spill here.
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Dalian Oil Spill, China

Sometime last week, two pipelines in the port city of Dalian, China, exploded and burned, and a large quantity of oil was released into the Yellow Sea. One firefighter lost his life. There are some harrowing pictures of oil-covered firemen being pulled from the water. Officials report that 165 square miles of ocean was covered with oil, but the pipelines are no longer leaking and cleanup is proceeding. Aquaculture is a huge business in China - Greenpeace estimates that 10,000 shellfish farms have been affected.

Envisat ASAR radar image (black-and-white) taken July 18, 2010

This Envisat radar satellite image appears to show patchy oil slicks spread out over a large area along the coast and islands near Dalian. China Central Television reported that the spill was estimated at about 400,000 gallons. If true this is far smaller than the BP /Deepwater Horizon spill in the Gulf of Mexico, although it's worth noting that any spill greater than 100,000 gallons is labeled "major" by the US Coast Guard.

Some of the dark patches in this radar image may be areas of calm water rather than oil. This is a rugged coast, and strong topography can generate "wind shadows" on the downwind sides of rocky islands and coastal hills.

SkyTruth - In The News

We've been getting a lot of TV, radio, print and Web interviews and other coverage since the BP / Deepwater Horizon spill began back in April. Media interest focused on our early determination that the oil spill rate was much larger than official BP and government estimates; testimony in November 2009 warning Congress about the risks posed by offshore drilling; discovery of chronic leaks from other wells in the Gulf; and call for systematic, Gulf-wide pollution monitoring using satellite imagery.

We have been busy. You can download reports listing our media and web appearances in April, May, June, and (so far) July. You might also be interested in reading our brand-new newsletter (Volume 1, Issue 1 - a future collectible!). Here are a few of the highlights:

TV appearances

• MSNBC, The Daily Rundown with Chuck Todd
• CNBC, America's Crude Reality
• CNBC, Street Signs (beginning at about 4:25)
• AP TV, Gulf Awash in 27,000 Abandoned Wells
• Fox News, ANOTHER Oil Rig Leaking into Gulf of Mexico

Radio

• NPR, All Things Considered, BP's Own Numbers Prove Spill Greater Than Estimate
• NPR, To The Point with Warren Olney

Print

• New York Times (Op-ed), The Measure of a Disaster
• New York Times, Size of Oil Spill Underestimated, Scientists Say
• New York Times, Estimates Suggest Spill Is Biggest in U.S. History
• Los Angeles Times, Tiny group has big impact on spill estimates
• Washington Post, 5,000 or 26,000 barrels a day: Size of gulf oil spill is a guesstimate
• Wall Street Journal, Experts: Oil May Be Leaking at Rate of 25,000 Barrels a Day in Gulf
• Miami Herald, Gulf oil spill has 'perfect precedence' in 1979 disaster

Web

• CNBC, Deepwater Oil Risks Greater Than Industry Admitted
• Huffington Post, Mary Landrieu Minimized Potential for Spill and Impact of Damage
• Mother Jones, Two More Gulf Spills?
• New Scientist, SkyTruth founder: Remote sensing for the people

Satellite Imaging of Oil Slicks - A Primer

We get a lot of questions from folks interested in our work using satellite images to detect and monitor oil spills around the world. The Montara spill off Australia last year, and the ongoing BP / Deepwater Horizon spill in the Gulf of Mexico, are striking examples of how this technology can help us investigate and illustrate what's happening far out to sea and in remote locations.

Like all data sources, satellite imagery has its strengths but also some important limitations. Few imaging satellites (the ones taking pictures of Planet Earth) are "turned on" all the time, so images are not necessarily available. Usually somebody has to contact the satellite operators - some operators are government agencies, some are commercial for-profit businesses - and request that images be collected over an area of interest. Often, you've got to pay to have this done. NASA makes images from their taxpayer-supported systems, including MODIS, available for free, but satellite images from private vendors can cost thousands of dollars each.

Imaging systems that operate at visible to infrared wavelengths of light, like the MODIS system we've used so often, can't see through clouds, smoke, dust or haze. And oil slick imaging is sometimes dependent on the sunglint pattern, which varies considerably from one image to the next, and is also affected by wind and wave conditions on the water. Radar imagery gets around some of these problems, but NASA doesn't operate any radar satellites so the cost can be prohibitive.

For all of these reasons, we haven't been able to produce good images of the BP oil slick every day (NASA just published an excellent illustrated article on this topic). But at SkyTruth we have acquired good images often enough to illustrate the enormity of the spill and inadequacy of our initial spill response efforts; provide the first estimate of the spill size and rate that made any sense; to identify oil making landfall along the Alabama coast before it was being acknowledged by officials; to show clear entrainment of the spill in the Loop Current while officials were actively denying it; and to detect small but chronic leaks from other damaged wells, raising the related issue of inadequate plugging and abandonment.

This spill has also provided a unique opportunity to collect imagery from multiple different remote-sensing systems, both satellite and airborne, working at visible to infrared to microwave wavelengths, over a long period of time under a wide range of weather and illumination conditions. A systematic analysis of this dataset will yield a much better understanding of how imagery can be used to accurately measure and monitor oil pollution events in the future. We're looking for funding opportunities to conduct such an analysis.

Because as long as we continue to produce and transport oil offshore, there will be a next time.

Hopefully not too soon.

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.

Platform 23051 / Ocean Saratoga Site Revisited

June 5, 2010: Oil slick next to Ocean Saratoga semisubmersible drill rig. Rig is working to plug leaking wells that were damaged by Hurricane Ivan in 2004. Photo courtesy J. Henry Fair.

June 25, 2010: Oil sheen marked by orange buoy. Rig was not observed in the area. Photo courtesy J. Henry Fair.

A few weeks ago we noticed a small but persistent slick on satellite images, appearing near a known oil platform location, designated Platform 23051 in a government database of all Gulf oil and gas platforms (including platforms that have been destroyed or removed). J. Henry Fair, a professional photographer, was flying over the site a few days later and captured photos and video showing an oil slick next to a semisubmersible drilling rig called the Ocean Saratoga. We learned the rig was not the source of any leak - it was working to plug one of 26 leaking oil wells that had been damaged by Hurricane Ivan in 2004, and have apparently been leaking ever since. Platform 23051 must have been destroyed during Ivan, or so badly damaged that it was subsequently removed.

The Coast Guard reported the wells were leaking, on average, just 14 gallons per day; and a containment device was said to be capturing most of that oil. But based on the size of the oil slick, we calculated a leakage rate in the range of 100-400 gallons per day. In our most recent observation on satellite imagery, June 18, the oil slick is 12 miles long and covers 4.5 square miles. The Ocean Saratoga is apparent as a bright dot on the radar image near the western end of the slick.

Mr. Fair flew over the site again on June 25 and took photographs showing a thin oil slick (rainbow sheen) marked by an orange buoy at one end, with no sign of the Ocean Saratoga rig or any other activity. It's possible the rig was towed back to shore to ride out tropical storm Alex, or has been moved to another job. As long as we keep getting satellite imagery covering the nearby BP oil spill, we should have more opportunities to check up on the progress at stopping this small but persistent leak.

BP / Gulf Oil Spill - Radar Images Show Western Reach of Slick, June 28

Two CSK radar satellite images (black-and-white) are superimposed on a cloudy MODIS satellite image (color) taken June 28, 2010. The radar on the left was acquired at 6:56 pm, and the image to the right at 7:44 pm local time on June 28. Only the western half of the oil slick is visible on these images:

COSMO-SkyMed (CSK) radar satellite images acquired June 28, 2010. Images courtesy of CSTARS.

Tropical Storm Alex was roiling the Gulf when these images were taken. Weather data buoys in the vicinity recorded wind speeds of 6-11 meters/second (13-25 miles/hr), strong enough to break up areas of thin oil sheen and possibly render them undetectable. We infer that the dark areas enclosed within the orange line are thicker patches of oil slick. Oil is reaching farther to the west than we've seen recently, impacting Timbalier Bay and Terrebonne Bay.