Showing posts with label Chevron. Show all posts
Showing posts with label Chevron. Show all posts

Friday, December 16, 2011

Chevron Oil Spill, Brazil - Small Slick December 6, 2011

Envisat ASAR radar image taken December 6, 2011. Image courtesy European Space Agency - click for larger version.
We've been getting a few Envisat ASAR radar satellite images of the Campos Basin off the coast of Brazil, covering the Frade field, where Chevron and their contractor Transocean experienced a loss of well control during drilling on November 7 that initiated an oil spill. Apparently "unexpected" reservoir pressure caused drilling mud to back up in the well, allowing highly pressurized oil (and probably some gas) to leak out into the surrounding bedrock.  This oil has since been working its way up to the seafloor through faults or fractures in the rock, emerging along a line of unnatural seeps on the seafloor, and floating up to the surface to create visible oil slicks.  The well was plugged a week after the spill began, and since then visible slicks have diminished in size. 

Chevron may also be required by Brazilian authorities to drill a relief well to inject cement into the well at depth -- an expensive proposition -- to formally abandon the failed well.  And a Brazilian federal prosecutor based in Campos has filed a $10.8 billion suit against Chevron and Transocean, and is seeking to have both companies permanently banned from drilling in Brazil. 

Meanwhile in Bohai Bay, China, ConocoPhillips has found little environmental damage from their spill earlier this year in the Peng Lai 19-3 field.  But they did reveal that their spill, like Chevron's, was caused "due to unexpected pressure encountered while drilling."  A mistake like that can lead to a blowout and major spill.  I hope all of the technical details from both of these incidents are being disclosed and will be made available to the public and to US regulators.

The radar satellite image above, taken on December 6, 2011, shows a very small slick originating near the location of Transocean's SEDCO 706 drilling rig that was installing Chevron's failed well. The slick is about 7.3 miles long and a few hundred yards wide, comparable to the slicks created by natural oil seeps in the Gulf of Mexico.  Wind conditions were good for slick detection at the time, blowing at about 10 knots (5 meters per second).  Several other small slicks are visible near a cluster of oil platforms (bright spots) about 50 miles south of the SEDCO 706.  This is within the southern Campos Basin, and these slicks may be the result of minor spills or leaks from platforms, pipelines, or vessels operating in one of the many offshore fields in the region.

Thursday, December 1, 2011

Campos Basin Oil Spill, Brazil - Small Slick November 25

We've just processed an Envisat ASAR radar image of the Campos Basin that was taken on November 25.  As expected, it shows a much smaller apparent oil slick originating from the location of the SEDCO 706 drilling rig, operated for Chevron by Transocean, than we observed back on November 12:

Envisat ASAR satellite radar image taken November 25, 2011. Slicks are dark streaks and patches. Location of SEDCO 706 drill rig is marked. Image courtesy European Space Agency.
Surface wind speed over the leak site was good, about 5-15 knots (3-8 meters/sec), blowing from the north-northeast.  A very narrow slick about 120 meters wide and 50 kilometers long extends south from the rig location, covering about 6 square kilometers.  Assuming the slick is 1 micron thick, we estimate it holds about 1,584 gallons (38 barrels) of oil.

There are other small slicks in the area to the west and southwest of the Chevron leak site.  Some of these may be from natural oil seeps in the basin, other sources of natural surfactant such as phytoplankton, or leaks and spills from vessels and other offshore facilities.

Tuesday, November 22, 2011

Campos Basin Oil Spill, Brazil - Slicks Dissipating?

Envisat ASAR image of Campos Basin taken November 22, 2011. Surface winds too strong to reliably detect thin oil slicks. Bright spots are vessels and oil platforms. Image courtesy European Space Agency.

Today's Envisat ASAR satellite radar image of the Campos Basin, covering the location of the Chevron / Transocean oil spill, shows no sign of an oil slick. It was taken at about 9:30 am local time.

However, the wind speed was fairly strong in the area at the time. According to the satellite scatterometer data collected by the ASCAT system, surface winds were blowing at 15-25 knots (8-13 meters per second). This is strong enough to overwhelm very thin oil slicks (the optimum wind speed for detecting slicks on radar images is about 3 - 10 meters per second):


Surface wind speed and direction derived from ASCAT scatterometer data at nearly the same time as the November 22 radar satellite overpass.

So it is possible that very thin oil slicks remain in the area, but it is encouraging that we don't see signs of thick oil... (more text and images after the break)

Friday, November 18, 2011

Aerial Photo and Video from the Campos Basin Oil Spill, Brazil

Aerial view of oil spill in the Frade Field, Campos Basin, Brazil, on November 18, 2011. In the background is the Transocean semisubmersible drill rig operated for Chevron. Photo copyright Marcia Foletto/Agencia O Globo - All rights reserved.

While we're still waiting on clear satellite imagery from the area (and radar imagery, coming next week), the aerial photograph above was taken during an overflight on the morning of November 18 off the Campos Basin along the coast of Brazil. According to Chevron and Brazilian authorities, the well is now sealed.

BBC News also has a short video clip showing aerial footage of the spill and the vessels in the area trying to clean up the mess. Brazil's oil agency, ANP, said underwater images showed Chevron's effort to permanently seal the well with cement appeared to have been successful, although there appeared to be a residual flow of oil from the seabed.

Thursday, November 17, 2011

Brazil Oil Spill - Well Plugged, Leaks Abating

We are still waiting to get more good satellite imagery of the Chevron / Transocean oil spill in the Campos Basin - it's been cloud-covered since our last image on November 12, so we've been unable to provide any new information.

But we are happy to pass along that Brazilian authorities report the well was plugged yesterday with cement, and the leakage from nearby points on the seafloor is greatly diminished. We expect to see a much smaller oil slick, if any, when we get another good satellite image of the area.

Brazilian Federal Police have launched an investigation into the causes and size of the spill. We hope all of this information becomes public: deepwater drilling is a global business and these were two of the biggest global players, so lessons learned from this incident will apply here in the U.S. too.

Wednesday, November 16, 2011

Brazil Oil Spill Update

The Campos Basin has been cloudy so we haven't gotten a good satellite image of the Chevron oil spill there since November 12. Chevron reported yesterday that their top-kill operation has stopped the flow of oil at a well they had been drilling from the Transocean SEDCO 706 semisubmersible drill rig, and "significantly reduced" the flow from from a line of nearby seeps that may have been fed by oil from the well.

It seems like they may have had a casing failure below the seafloor, but we need to see a lot more technical detail about what happened. Chevron and Transocean are major global players, very active in US waters, so whatever went wrong off Brazil is important information relevant to deepwater drilling everywhere.

Let's not make the mistake of dismissing this spill as irrelevant to US drilling practices, like we did after the 10-week-long blowout and oil spill off Australia in 2009. These incidents are warning shots that we ignore at our peril.

We'll keep looking for good satellite imagery of this spill - hopefully showing the oil slick dissipating - and will update you all here and at SkyTruth Alerts whenever we produce anything new.

Tuesday, November 15, 2011

Chevron Oil Spill off Brazil - 10 Times Bigger Than Official Estimate?

We've been tracking the oil spill reported off Brazil a few days ago, in the Frade field operated by Chevron in the Campos Basin, Brazil's most productive area of offshore production, and a place where many deepwater technology milestones have been made for offshore oil production.  Chevron claimed the oil slick was being caused by a natural oil seep on the seafloor, but they suspended drilling on a well in the field.  Brazilian authorities quickly disputed that a natural seep was the cause.  And yesterday Chevron admitted the possibility that something went wrong at their drillsite.  According to today's news release from Brazilian authorities, Chevron is trying to kill the well - indicating a loss of well control and blowout. 18 response vessels are on the scene, and Chevron reports the well is leaking about 8,400 - 13,860 gallons  (200 -330 barrels) per day.

MODIS/Aqua satellite image shows growing oil slick in the deepwater Campos Basin off Brazil.  Image taken around midday on November 12, 2011.

Thursday, November 10, 2011

Oil Spill off Brazil Seen On Satellite Images

We don't have much information on this yet but Chevron is reporting an oil spill in their Frade field in the Campos Basin off Brazil.  Two MODIS satellite images from NASA, taken yesterday, show an apparent oil slick about 35 miles long and covering about 180 square kilometers, 80 miles offshore due east of the city of Campos. Assuming this slick is only one micron (1/1000th of a millimeter) thick, then it represents about 47,000 gallons.

This Terra image, shot at about 1 pm local time on November 9, has a sunglint pattern over the area that reveals the slick as a bright streak. At first we just thought it was a bank of clouds until we noticed it didn't cast any shadow, like the other clouds in the area:

November 9, 2011 MODIS/Terra image of oil slick off Campos, Brazil. Image courtesy NASA/Rapid Response Team.

And this Aqua image taken a couple of hours later clinched it as a slick: the sun angle has changed enough so the sunglint pattern has moved, and the slick now appears mostly dark.  It's in the same place, but the clouds have all changed dramatically compared with the Aqua image:

November 9, 2011 MODIS/Aqua image of oil slick off Campos, Brazil. Image courtesy NASA/Rapid Response Team.
 The slick seems to be originating from a continuous point source of leakage at its north end.  It also looks thicker at the north end, as you'd expect - it's brighter there on the MODIS/Aqua image suggesting the slick is thick enough to have its own distinct spectral response, not just a sunglint signature.  We hope they get the source of this under control soon.