Tuesday, December 27, 2011

Oil Pollution off Nigeria - Other Sources?

After flying journalists over the remnants of the Bonga FPSO oil spill off Nigeria,Shell pointed out that they are not the only polluters in this part of the world, and will clean up another small spill in the area not related to any of their operations.

That certainly doesn't excuse their (much larger) mess but they are correct:  satellite images of the west coast of Africa, like some other coastal regions around the world, routinely show signs of oil pollution from other sources, especially bilge-dumping by vessels large and small. We don't know if it's legal in this area; it is not legal in US or Canadian waters. Radar satellite imagery is an excellent tool for detecting bilge-dumping

This Envisat ASAR image taken on December 18, 2011 shows a 100-mile-long slick caused by bilge dumping from a large vessel that was traveling toward the southeast on a course taking it very close to the Bonga FPSO (we've inferred the location of the FPSO from multiple radar satellite images; if anyone has the exact lat/lon coordinates please pass them along to us): 

Envisat ASAR image taken December 18, 2011 showing oily bilge dump from a passing vessel northwest of the Bonga oil field off Nigeria. Image courtesy European Space Agency.

At 1 micron thick this bilge slick holds about 80,000 gallons of oily material.  Projecting the vessel track back to the northwest, we land near the city of Aneho on the Togo coast. There is an industrial facility in the area that appears to have an offshore loading system.  It could be the point of origin for the suspect vessel, but we really have no way of knowing:

Projecting backward along bilge slick to shore. Envisat ASAR image courtesy European Space Agency.

Here's what it looks like in Google MapsDoes anyone have any information about this facility?

Shell Oil Spill off Nigeria - How Big?

Shell has declared victory over the major oil spill from their Bonga FPSO off Nigeria, claiming the slick was halted 12 miles offshore and has mostly dissipated, thanks to evaporation plus the use of chemical dispersants. Our observations of satellite images over the past few days don't indicate anything to the contrary.

How big was this spill?  We think the amount spilled is near the high end of Shell's estimate of "up to" 1.68 million gallons, based on the size of the oil slick observed on December 21 and the photos provided by Shell showing a rainbow sheen.  The thickness of "rainbow sheen" is in the 5 to 10 micron range according to the CONCAWE guidelines, and 0.3 to 5 micron range according to the BONN convention. The overlap -- 5 microns -- would mean a spill of at least 1.2 million gallons (28,571 barrels).

On their website Shell reported the slick was "less than a hundredth of a millimeter" thick in most areas. 1/100th of a millimeter is 10 microns, which would be a spill of 2.4 million gallons -- 58,000 barrels.

Assuming Shell, like most successful companies, is fanatical about inventory control they should be able to provide an accurate measurement by comparing the amount pumped out of the FPSO with the amount that actually ended up in the shuttle tanker. Flow meters on the pumps and transfer lines, and gauges in the tanks, should allow them to calculate the spill with precision.  Let's ask them for those numbers and settle the question.

Regardless of the specific amount spilled, we're left with some troubling questions, most notably: how could up to 1.7 million gallons of oil steadily leak into the ocean before anybody noticed and took action? The crack in one of the transfer lines that Shell blames for this leak looks like it could only divert about 5-10% of the flow through that line. How long would that take to amount to 1.7 million gallons?  This is just the latest example of the many mundane, low-tech ways that modern offshore oil production still poses risks -- even when it's being done by one of the biggest, technically accomplished, retail-brand-sensitive multinational oil companies (hmm, that sounds familiar...).

Friday, December 23, 2011

Shell Oil Spill - Moving Toward Nigerian Coast

Yesterday's MODIS satellite images were a bust, but today's were slightly less cloudy/hazy.  Both the Terra and Aqua images show a pale patch of ocean water about 18 kilometers offshore, covering a total area of about 678 square kilometers.  But this is a tough call - the image quality really isn't very good.  The closest sizable populated area near this part of the coast, according to Google Earth, is the town of Burutu located at top center on this graphic:
MODIS/Terra satellite image taken December 23, 2011 at 10:10am local time. Possible location of oil slick noted. Image data courtesy NASA/MODIS Rapid Response Team.
This fuzzy patch that may or may not be the remnants of the oil slick is located about where we would expect to see it, given the wind speed and direction over the past couple of days (blowing from the south-southwest at 5-10 knots). Radar imagery would give us a better look but we haven't seen any new radar images since December 21.

So far we haven't heard that any oil has come ashore.  Shell reports they have mounted a vigorous response, including the use of chemical dispersants to break up the oil slick.

Yesterday Shell also released this photograph showing what purportedly caused the leak - a small crack in a transfer line at their FPSO.  Engineers, tell us - how long would it take to spill >1 million gallons of oil from a relatively small break like this?  I don't know the diameter of this line; possibly 20" or so?

Photograph reportedly taken by ROV showing crack in transfer line. Photo courtesy Shell.
 Let us know if you have any expertise on flow rates through pipelines, and are willing to provide some expert opinion on this. 

Thursday, December 22, 2011

Shell Oil Spill off Nigeria - Questions....

We've got a few questions for you savvy engineers out there about Shell's spill during loading at their FPSO in the Bonga field off Nigeria.  Based on the size of the oil slick on satellite images yesterday, and photos of parts of the slick released by Shell along with statements made on their website (scroll down to read the comments), we think that the spill may be near the high end of Shell's public estimate of up to 1.7 million gallons (40,000 barrels). 

According to Shell, this spill occurred during the transfer of oil from the FPSO to a tanker.  Oil from the FPSO was being pumped into the tanker. Or as it turns out, was being pumped into the water. So here are the questions: 
  1. How long does it take the workers onboard to notice that, hey Houston, we've got a problem here?
  2. How long does it take to shut off that pump? 
  3. How long would it take to pump 1.7 million gallons of oil into the water? 
Please let us know by commenting on this post if you have any expertise in this area and can help shed some light on how a spill of this size could have occurred during the routine transfer of oil from an FPSO to a tanker.

Nigerian authorities are predicting that oil will begin to come ashore this afternoon.  

Sunoco's Ongoing Leak in South Philly

Since November 8, there have been 8 different reports to the National Response Center coming out of the Sunoco Oil Refinery in South Philadelphia. The initial report stated that oil from an unknown source accumulated and discharged into the Schuylkill River. Subsequent reports state that absorbant booms and pads had been placed in the water to absorb the sheen. The booms were repositioned and then changed out and additional absorbant pads were deployed, and still the reports keep coming in. The latest report from yesterday states that a vac truck is onsite to aid in removal of oil.

I lived in South Philly, 2.5 miles from where this oil is leaking into the Schuylkill River. I have 3 brothers who live exactly 1 mile away from the Sunoco Refinery. Thanks to the SkyTruth Alerts System, I can see exactly what's happening in my old neighborhood, and I can see that Sunoco obviously has a problem at their South Philly refinery and they're cleaning up the mess but it doesn't sound like they've found the cause of the problem.

I'll keep monitoring the area with my daily alerts, and I'll be letting my brothers know that swimming in the Schuylkill River down by Sunoco probably isn't a great idea this holiday season.

Wednesday, December 21, 2011

Another Satellite Image of Shell Oil Spill in Nigeria

Less than an hour after Envisat captured a stunning radar image of Shell's big oil slick off Nigeria, NASA's MODIS satellite flew over.  The Terra instrument on MODIS took this visible-infrared image that also shows the oil spill peeking through the clouds and haze that typically obscure this part of the world: 

Detail from MODIS/Terra satellite image showing oil slick off Nigeria on December 21, 2011 at 10:15-10:20 am local time.  Image courtesy NASA/MODIS Rapid Response Team.

The slick coincides exactly with the slick on the radar image - no surprise there - but it does appear slightly smaller. On this MODIS image, the slick is showing up as a spectral feature, a target with a distinct reflectance signature typical of floating oil (high reflectance at shorter wavelengths, making it appear pale blue-ish in color).  On a radar image, oil slicks are textural features: they smooth out the ocean surface, causing specular reflection of the incoming radar energy being beamed down at earth by the radar instrument. The very thin edges of the slick look transparent to MODIS but are still able to smooth out the water and appear dark on radar images under suitable wind conditions.  Scatterometer data show that the surface wind speed was probably in the 5 to 10 knot range, ideal for slick detection on radar. 

Which brings us to the amount of oil spilled.  Shell has reported "less than 40,000 barrels" were spilled, so the amount could be anywhere from 1 gallon to 1.7 million gallons.  Based on the radar image today, the oil slick covers 923 square kilometers.  At an average thickness of 1 micron (1/1,000th of a millimeter) that would amount to 243,672 gallons (5,802 barrels) of oil.  But portions of the slick could be many times thicker than that; it's not unusual for a spill directly to the sea surface to be millimeters, or even centimeters, thick.  Estimating the thickness is usually based on direct visual observations of the slick, especially the color.

It would be very helpful to get photos or video of this slick taken from the air and on the water. 

Shell Oil Spill, Nigeria: FPSOs Coming to the US

Shell's big oil spill off Nigeria yesterday reportedly occurred during the transfer of oil to a tanker in their Bonga offshore field.  Oil is produced in the Bonga Field using an FPSO - basically, a modified oil tanker anchored in place.  Oil collected from wells on the seafloor flows up through riser pipes connected to the FPSO.  Shuttle tankers take crude oil out of the FPSO's storage tanks and carry it to coastal refineries. Here's a schematic diagram showing the Bonga Field layout:

FPSO operation at Bonga Field off Nigeria. Image courtesy Offshore Technology.

In March 2011, federal regulators approved the first-time-ever use of FPSOs to develop an offshore field in the US Gulf of Mexico.  Petrobras got the nod for their Cascade-Chinook development in water 8,200' deep, 160 miles off the Louisiana coast.  Their FPSO, a converted tanker called the BW Pioneer, holds 600,000 barrels of oil (25.2 million gallons). BOEMRE and Coast Guard divvied up oversight responsibility for this vessel / production facility with an MOU in 2009. This project got off to a very poor start when 8,500' of riser pipe went crashing  to the Gulf seafloor back in early April.

Our main concern is that FPSOs are potentially sources of massive oil spills:  a serious blowout, fire or explosion, collision with another vessel, intentional attack, rogue wave or storm damage, or other incident could result in a near-instantaneous release of millions of gallons. And as we've said here before, despite the underwhelming oil cleanup results during last year's BP / Deepwater Horizon spill, we've made no significant progress in our ability to handle big spills.

Shelling out the Oil in Waters off Nigeria: Radar Satellite Image December 21, 2011

Envisat ASAR satellite radar image showing large slick (black) from major Shell oil spill off Niger Delta.  Image taken December 21, 2011 at 9:30am local time.  Image courtesy European Space Agency.
Royal Dutch Shell's Nigerian drilling operations in the highly productive Bonga Field were officially brought to a halt yesterday after "less than 40,000 barrels of oil" (1.7 million gallons) were reportedly leaked during a transfer of crude to a tanker. We've just processed a radar satellite image taken this morning (December 21, 2011) of the field, with the spill clearly visible.  Here it is showing the slick outlined in yellow; it is about 70 km (45 miles) long, 17 km (10 miles) wide at it's widest, and covers 923 square kilometers (356 square miles) of ocean: 
Another, much smaller oil slick appears at lower right; this looks like a bilge dump from a passing vessel, not related to the Shell spill.

Located 120 km off the the Nigerian coast, the Bonga Field is the first deepwater oil exploration and production project for the country since Shell began offshore drilling there in 2005. Shell's onshore operations in the Delta have a long history of spills.

Map showing location of Bonga Field off Nigeria. Courtesy Marcel De Jong, Shell Deepwater Services Regional Study Team.

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.

Taylor / 23051 Chronic Leak Site in Gulf: Oil Analyzed

Back on September 15, a team from National Wildlife Federation piled onto a small boat on the Louisiana coast.  Their destination: the chronic leak site about 12 miles offshore where a cluster of wells operated by Taylor Energy has been steadily spilling oil into the Gulf since 2004.  Check out this aerial video of the site, shot by On Wings of Care on December 9, 2011:


Their objective: to collect samples of the Taylor oil slick for analysis, to see if it's chemically distinguishable from the oil that gushed from BP's infamous Macondo well about 30 miles away.  We wanted to know if other samples of oil collected in this region of the Gulf, on beaches and barrier islands and from slicks observed offshore, could possibly be coming from the Taylor site since it's a well-documented source of oil pollution. The NWF team -- coached in advance by Dr. Ed Overton at Louisiana State University on proper collection and sampling technique -- succeeded. Dr. Overton analyzed the Taylor oil samples and in mid-October told us "these were heavily weathered oil with slight differences in the fingerprint pattern from the Macondo oil."  (more after the jump....)

Wednesday, December 14, 2011

Gas Drilling Heating Up West Virginia

Although most of the recent natural gas drilling coverage has centered around the Marcellus Shale play in Pennsylvania, West Virginia has never been out of the loop when it comes to energy resource extraction.

Oil, natural gas and coal bed methane industries have quietly grown alongside the long-entrenched coal business in the state, but as production ramps up across the nation, West Virginia's natural gas drilling is drawing increased attention.

(maps and more after the jump)

Friday, December 9, 2011

Gulf of Mexico Overflight Yesterday - Old Slicks, New Slicks

Jon Henderson of Gulf Restoration Network did an overflight over the Gulf yesterday, thanks to our Gulf Monitoring Consortium partner SouthWings. They documented two small slicks in Breton Sound, and a larger slicks from the Taylor Energy site where a cluster of hurricane-damaged wells have been leaking since 2004.  Read all about it and check out the excellent pics

Jon filed three reports with the National Response Center, as all citizens who witness a suspected oil or hazardous materials spill are encouraged to do.  His reports should appear soon in the SkyTruth Alerts system, which you can subscribe to if you'd like to get automatic notifications any time a spill is reported. But in the meantime you can see Jon's two Breton Sound reports here and here, and the Taylor report here.

Oil slick at Taylor Energy / 23051 chronic leak site in Gulf of Mexico, December 8, 2011. Photo courtesy Jon Henderson / Gulf Restoration Network.

Judging from the pics, it looks like both Breton Sound slicks are being caused by a slow point source of leakage underwater, probably on the seafloor.  The first is similar to what you'd see at a natural oil seep location; the second contains heavier brown material that suggests a larger/faster leak.  Given the maze of pipelines and abandoned wells on the seafloor in the Sound, both might be from leaking infrastructure.  We'll check the NRC to see if any potential responsible party has come forward. 

The slick at the Taylor Energy / 23051 site is similar to what we've been seeing since we first "discovered" this chronic leak in early 2010. A work boat of some kind is on the scene, but the Ocean Saratoga rig that was working to plug the leaking wells is obviously not. Apparently fixing these wells and stopping this leak isn't a high priority. Check out a chronology of information and observations related to this leak. You can monitor this location on the SkyTruth Alerts, or subscribe to get automatic notifications.

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.