Improving weather, different sampling methods

As the weather improved we made steady progress working our way east towards the northeast peak of Georges Bank. The weather was so good that on Friday we made a second deployment of our In Situ Ichthyoplankton Imaging System (ISIIS) device on the southern flank of Georges Bank, running a transect from the bank itself off into the slope water for a comparison of the hydrographic conditions and zooplankton in both areas. This was undertaken successfully, along with a series of comparison bongo net plankton tows, to supply ground-truth samples for comparison with the many images taken by the ISIIS video camera.

On Friday evening one of the crew members was taken ill, and the Delaware II steamed back towards Cape Cod to rendezvous with a Coast Guard vessel. The person was transferred to that vessel on Saturday morning and taken ashore for medical attention.   By Sunday we had returned to our work area on the northeast peak of Georges Bank, continuing our sampling operations there and in the Northeast Channel, a particularly interesting area that marks an entry point where the Labrador Current brings cooler, less saline water from the northern ice shelf into the Gulf of Maine. With continued excellent weather, and less swell from Hurricane Danielle than had been anticipated, a repeat deployment of ISIIS was undertaken on Sunday evening, on the exact same transect made two days earlier, to replicate that sampling effort under nocturnal conditions to determine if we could observe any faunal changes.

It is interesting to compare plankton sampling by these two different methods. The bongo sampler, so named because of its side by side aluminum plankton net frames, is lightweight (about 50 lbs.), extremely rugged , and coupled together with a Conductivity, Temperature and Depth (CTD) device  provides two plankton samples and simultaneous salinity, temperature and depth information. It can also be deployed with only three people on deck; one to run the winch, one to run the A-frame, and one to handle the gear, which consists of the aluminum bongo frame with nets and flow-meters, the CTD and a 45 kilogram (about 100 pounds)  lead weight to act as a depressor. This array can be fished in seas of up to ten feet with winds of up to 30 knots before it becomes too dangerous to deploy safely.

Science teacher Scott Sperber retrieves the bongo sampler. Visible are the attached lead weight, which he is pulling on, and the white CTD unit above the bongo frame. (Photo by Jerry Prezioso, NOAA)

The ISIIS requires much more care and manpower for safe deployment. The 900-pound device is lowered and retrieved from the stern of the vessel through the trawl-way. It requires a larger number of people to deploy safely, with one person running the winch, one person running the hydraulic gantry, and four people manning tag lines to prevent the instrument from sliding sideways against the trawl-way and damaging its diving wings. On the Delaware II it can only be safely deployed in winds of 10 knots or less, and seas of five feet or less.  Once in the water,  it too will measure temperature and salinity at different depths, and with its camera provide plankton identification and abundance information by depth, something that the bongo sampler, with its double oblique tow through the entire water column does not.  Additional sensors on ISIIS also provide dissolved oxygen, light and chlorophyll levels. ISIIS can be “flown” up and down through the water column by a “pilot” on board the vessel and towed for a distance of approximately 30 miles at five knots before overwhelming its computers with data from its camera which is snapping images at 17 frames per second. This ability to be towed at speed for a considerable distance makes it a particularly useful tool for mapping changes across large frontal areas, such as between shelf and slope water.

It takes quite a few hands to retrieve the ISIIS system and get it aboard ship. (Photo by Delaware II Commanding Officer Steve Wagner, NOAA).

Perhaps oneday, these diverse systems will be integrated into something that combines the best of both: the simplicity and durability of a net sampler with the depth discrete imagery and suite of hydrographic data that the ISIIS can provide over a large area. Until that time comes, we’ll be often manning cruises much like this one, using mostly nets but relying increasingly on electronic instrumentation to gather data about long term trends in our changing marine ecosystem.

Jerry Prezioso
Chief Scientist

Chow Time!

The Delaware II left its sheltered anchorage in Provincetown at dawn on Wednesday.  We weighed anchor at 6 a.m. and worked  our way east onto Georges Bank for more plankton sampling and a second transect of the ISIIS towed body video system.  With the storm system that had pinned us down moving away to the east, conditions improved slowly but steadily, although residual large seas made getting to the first station a long rough ride!

A view from the bridge as the Delaware II plows through large seas working its way east after leaving Provincetown.

Pembroke High School student and Naval Sea Cadet Anthony Gomes washes off the ship's anchor chain.

One thing that will always lift my spirits during these down times is the food we are served aboard this vessel.   Regardless of the conditions outside, Chief Steward John Rockwell and Second Cook James White  are always busy preparing three meals a day in the Delaware II’s tiny galley, plus  baking pastries for desserts or morning coffee break to ensure that everyone aboard is well nourished!

Chief Steward John Rockwell and Second Cook James White preparing one of many excellent meals in the galley on the Delaware II.

Entrées range from a variety of meats – chicken, beef, lamb, and pork – to fish and shellfish,  prepared in different ways on different days.  We’ve had a variety of pasta dishes as well: manicotti, ravioli and the perennial favorite, spaghetti and meatballs,  embellished with a light garlic seasoning by the Chief  Steward.

Scientists Dave Richardson and Adam Greer enjoy dinner in the mess area.

A variety of vegetable side dishes, a salad bar, and fruits ranging from apples, bananas, and grapes to blueberries and strawberries for breakfast, round out the food groups.  Breakfasts feature hot and cold cereals, pancakes, waffles, and eggs prepared in a variety of ways,  with bacon or sausage, as a sandwich with cheese, and of course, as omelets.  Coffee drinkers will find that their coffee beans are fresh-ground onboard the vessel right before the coffee is brewed, for a truly fresh flavor.

A freshly-baked chocolate and strawberry cake.

Coming to the mess area for chow is definitely a high point in everyone’s day. There is always the Delaware II “gym” (an exercise bicycle in the wet lab area) available to work off any excess calories!

Our teacher-at-sea Scott Sperber, working out in the "gym."

Helping to deploy and retrieve our gear is another way to burn calories, and we’ll talk more about these operations in a subsequent update.

Jerry Prezioso
Chief Scientist

The Whims of the Weather

Monday, August 23,  finds us at anchor in Provincetown Harbor at the tip of Cape Cod, waiting for a large storm system which has brought rain and wind to much of the Northeast to pass.  We’ve had excellent weather until this morning.  The calm seas which facilitated ISIIS operations on Stellwagen Bank continued for much of the past week, allowing us to collect plankton samples from most of the Gulf of Maine in just five days of work.

The timing of the summer ecosystem monitoring cruises, in August during summer vacation, makes them an attractive volunteer opportunity for teachers and students.   Joining us on this trip is Scott Sperber, a science teacher from the Sherman Oaks Center for Enriched Studies in Tarzana, Calif.  He has assisted us in collecting plankton and water samples and taking calibration samples for our flow-through sampling system, which continuously measures the temperature, salinity and chlorophyll levels of the near-surface water that the ship is traveling through.

Scott Sperber running the plankton tow by watching the real-time depth display coming from the Conductivity, Temperature and Depth (CTD) unit mounted above the net. (Photo by Jerry Prezioso, NOAA)

In addition, he has launched a NOAA drifter buoy decorated with his school’s name and mascot, a knight.  Equipped with a five-meter long (about 16 feet) drogue or sea anchor, a thermistor and a transmitter, this buoy will follow the ocean current it is launched in, and send out daily reports on its location and the surface water temperature to an Argos satellite.  The data is then relayed to a website, where students at his school can go online to monitor “their” buoy.   This buoy was launched at our easternmost station of the entire cruise, 50 nautical miles south of Sable Island, Nova Scotia, and will continue sending out daily reports on its location and water temperature for about 400 days, after which its batteries will run out.

Science teacher Scott Sperber and his decorated drifter buoy prior to launch. (Photo by Jerry Prezioso, NOAA)

We also have aboard a high school student and Naval Sea Cadet, Anthony Gomes, who is a junior at Pembroke High School in Pembroke, Mass.  He has stood watches with the NOAA officers on the bridge of the Delaware II, and assisted with the deployment and retrieval of gear and collection of water samples.  Anthony hopes to join the Seabees after finishing college, and is gaining sea-going experience during his time with us.

Pembroke High School student and Naval Sea Cadet Anthony Gomes getting a water sampler and CTD unit on board. (Photo by Jerry Prezioso, NOAA)

Scott Sperber and Anthony Gomes carrying a bongo frame net. (Photo by Jerry Prezioso, NOAA)

Although data and sample collection comes to a halt while at anchor, the scientists aboard are already planning how to best manage their remaining time once we get back underway, hopefully by Wednesday.  Already contingency plans are being drawn up for possible alternate sites for the deployment of the ISIIS video system on Georges Bank if time and/or weather preclude its use at sites further south off Long Island and New Jersey.  Despite all our technology and forecasting ability, we are still subject to the whims of weather and will have to alter our schedule to best fit what we are dealt with.

Jerry Prezioso
Chief Scientist

Something Old, Something New

Just a few days after returning from the Gulf of Mexico and conducting  oil spill response research, the Delaware II left the Woods Hole Laboratory dock on Wednesday, August 18, to continue the Northeast Fisheries Science Center’s long-term Ecosystem Monitoring Program (EcoMon).

The EcoMon surveys, which monitor  environmental conditions  and marine resources, are conducted six times each year at 120 randomly selected stations throughout the continental shelf and slope of the northeastern U.S., from Cape Hatteras, N.C., into Canadian waters to cover all of Georges Bank and the Gulf of Maine. This area is known as the Northeast U.S. continental shelf Large Marine Ecosystem.

Unlike the past several EcoMon cruises, we are not working with scientists from Old Dominion University and NASA to provide data for the Climate Variability on the East Coast (CLiVEC) program.  This time we have two scientists from the Rosenstiel School of Marine and Atmospheric  Science (RSMAS) at the University of Miami accompanying us, along with their In Situ Ichthyoplankton Imaging System (ISIIS).

This remarkable towed body is able to provide high resolution video imagery and simultaneous hydrographic data while undulating through the water column as is it is towed along at 5 knots, or about 6 miles per hour.  We are hoping to integrate data collected with this system with data  we have collected from our long-term CTD (conductivity, temperature and depth) and bongo sampler operations.  We also have two scientists aboard from Staten Island College of the City University of New York making observations of marine mammals and birds, and a teacher from California to assist with our EcoMon data and samples.

We commenced work with ISIIS today on blessedly flat calm sea conditions and sunny skies.  We are now in the middle of Stellwagen Bank, towing the instrument through internal waves generated by the tidal flow rushing over the submerged peaks and valleys of this national marine sanctuary.  Using technology like this may yield insights into the transport of larval fish across this area, a topic which is not easily studied by conventional plankton sampling operations.

After our ISIIS operations are concluded today, we’ll return to our more routine bongo net and CTD operations for the next several days or so until we reach the Mid-Atlantic Bight, another area of interest for larval fish transport.  There, weather permitting, we’ll deploy ISIIS again, south of Long Island and off the coast of New Jersey.

As I watch the RSMAS scientists in the dry lab staring into the computer monitor outputs from ISIIS as they “fly” it behind us through the water column,  I think it’s ironic that the venerable Delaware II, now over 40 years old, is helping to usher in a new age of oceanographic exploration!

Jerry Prezioso
Chief Scientist

A lot of watching….

Water sampling in deep water is a slow and  tedious process. The conductivity-temperature-depth (CTD) instrument with water sampling carousel in a rosette pattern is lifted in the air by pulling up on the wire. A large metal frame, called an A-frame because it looks like the letter A, then swings out over the water and the instrument is lowered in. The following two to three hours are spent lowering the CTD at 50 meters (about 165 feet) a minute to near the bottom (~1500 meters, or roughly 5,000 feet deep) and then raising the CTD at 30 meters (about 100 feet) a minute back to the surface. The ascent is punctuated with stops to collect water samples, and turning the instrument off and then on adds a little extra time. Two to three hours of watching a computer screen for a scientist, and three hours of watching the winch controls for a crewman,  is a  typical CTD deployment.

General Vessel Assistant Carl Coonce and Skilled Fisherman Jon Jarrell deploy a CTD (conductivity, temperature, depth) rosette onboard the NOAA Ship Henry B. Bigelow. The Deepwater Horizon site is visible in the background. The CTD device detects how the conductivity and temperature of the water column changes relative to depth. Bottles mounted on the rosette are also used to collect water samples at different depths. Credit: NOAA.

The weather has been so calm that deployment and retrieval has been easy. The instrument comes aboard in reverse of how it went out. Once on board, various samples of water are taken from the bottles for analysis.

During the post-kill period when we were not permitted in the wellhead zone, we took on a gas chromatograph (GC), an instrument to separate and analyze chemical compounds in a sample,  and a scientist from the NOAA Ship Gordon Gunter, which was returning to port after working on the Deepwater Horizon incident response.   We also met the NOAA Ship Pisces and transferred our winch repairman to that ship, as the Pisces was having problems similar to those  we had, and getting the repairman aboard the Pisces as soon as possible would them save a lot of time.

The onboard gas chromatograph (GC) analyses water samples for the volatile organic compounds that are found in oil. This near-real time capability allowed us to know what we were sampling, unlike the weeks to months it will take to get the results from the other samples we have collected that will be sent to a laboratory onshore.  The results of the GC analyses were pretty clear:  no volatile organics at depth.

At a few stations, however,  we found toluene near the surface in low concentrations.  Toluene is a colorless,  flammable liquid obtained from petroleum or coal tar and used in fuels. The source of this contamination was unclear. If it was from oil, we would expect other volatile compounds to be present. We ran a number of control samples: rinse water only, dropping vials on the deck, holding water in bottles and then extracting. All of these controls contained no toluene, so at this point the source of trace amounts of toluene in surface samples remains unresolved.

The other water samples – the ones to be shipped off to a laboratory – will be analyzed for polyaromatic hydrocarbons (PAHs). These samples and their analyses will provide a much clearer picture of how much oil is left in the area around the wellhead. We were sampling within 10 kilometers or km (about six miles), and were part of a research fleet that had numerous ships sampling around the area of the well from 15 to 60 km (roughly 10  to 40  miles) distance.

As we neared the end of our cruise, we had made almost 30 CTD casts  - or more than 60 hours of scientists and crew watching the computer screen and the winch controls.

Jon Hare
Chief scientist

Kill and Kill Again

August 8, 2010

The NOAA Ship Bigelow entering the wellhead area to conduct an acoustic survey over the wellhead. Picture taken from DDIII, the rig drilling the relief well.

The days during and after the “kill” operation have been busy. During the operation we were not granted access to the wellhead region. The last thing anyone needed was another ship working through the area, distracting from the operation itself. We patiently circled outside the 1500 m looking for acoustic evidence of material escaping the wellhead region at depth and visual evidence of oil on the surface. We saw no acoustic evidence at depth, but the data were sent to acoustic experts on shore for more thorough analysis.

We did observe some oil on the surface: 1 to 2 foot diameter areas of sheen, one larger patch and numerous little whisps. Some of this was likely from all the ships operating in the area, but some may have been from the wellhead. Our efforts to collect these little spots were largely unsuccessful.
We used this time to prepare for water sampling. Our water sampler is twelve 5 liter bottles that go into the ocean all open on a carousel. The sampler is lowered to depth and then raised. Bottles are then closed at certain depths. Our problem was that sometimes the bottles would not close.

The electronic control from the ship goes through a number of steps before reaching the carousel to close the bottles. The computer running the whole operation is in a lab on the ship. This computer is connected to a deck box that contains the “brains” of the water sampler and other equipment on the carousel. The deck box is connected to slip rings on the winch, and through these slips rings to the wire used for lowering the carousel. The winch has a large drum with wire wrapped on it. To lower the equipment, the drum spins paying out wire. The slip rings allow for the electrical connection to be maintained between the deck box and the wire while the drum turns – one of many ingenious technical solutions that makes sampling the ocean possible.

The wire has the electrical wires inside and the weight bearing part outside. Think of it as normal wire, with copper inside and insulation outside. But in addition to insulation there is another layer of wire that hold thousands of pounds of weight. At the end of the deployment wire there is another ingenious solution to a problem – how to get the inner electrical wire out from the center of the weight-bearing wire while preserving both the electrical connection and the weight-holding capability of the outer wire.

The poured termination is the solution. The whole wire is passed through a steel fitting and the electrical wires are taken to the next step. Metal is then liquefied and poured into the fitting. Once the metal solidifies in the fitting you have a weight-bearing termination with the electrical wires coming out. These wires are then connected to the wires that connect to the carousel. This splice of wires is also special because it must be waterproof even at the extreme pressures of 1000’s of meter (see http://sssg1.whoi.edu/sssg/termination/termination.html for more information).

Somewhere in this electrical chain, we had a problem; it wasn’t that the carousel didn’t work; it worked most of the time, but not all of the time. Intermittent problems are the hardest to troubleshoot.

We changed everything we could see, with no luck. However, we found that if we turned the deck box off and then on again, everything would work for a while – usually long enough to collect all the water samples we wanted. The problem wasn’ fixed, but we had a work around.

We heard reports that the “kill” operation was for “all intents and purposes was successful.” We didn’t quite know what this meant, but soon after we were granted access to survey over the wellhead. Over the next three days we made more than 25 passes with our acoustic instruments. Although the acoustic signatures over the wellhead appeared lower, there was much more background noise. This noise made preliminary assessments difficult. We transferred data ashore for more thorough analysis.

We also were given the opportunity to start water sampling under the conditions that we could return to the wellhead on short notice. Working with our shore-side support, we decided to sample a set of stations 2.5, 5 and 10 km from the wellhead. With our water sampling carousel mostly working we started making casts.

Jon Hare
Chief scientist

Samples Off, Water On, Monitoring Continues

Our acoustic monitoring efforts continue. Since the beginning of the static kill operation, we have not been able to work inside 1,500 meters (about 4,900 feet or just under one mile). There is no clear passage through the area with all the ships, and the ‘kill’ operation doesn’t need us driving through the middle of the action.

Most of the ships working in the wellhead region are using dynamic positioning (DP), in which the ship’s propellers and thrusters  hold it in a constant position. In fact, it is a little strange to watch all these ships from outside the circle and realize that none are moving even as the wind and currents move around them. It is like  a village of 20 houses out in the country with very few other people and structures around.

This morning we moved samples from our ship to a supply boat for transport to shore. The water samples collected by the CTD were labeled and stored in a walk-in refrigerator onboard. The hydrocarbon analyses need to be conducted within seven days of collection, so we need to transfer the water samples to a vessel that takes them ashore to a truck that then takes them to a lab for analysis. The supply boat pulled up along-side and offloaded two NOAA Natural Resource Damage Assessment (NRDA) sample representatives. These people met with our onboard NRDA rep and data manager and reviewed all the documentation: the sample numbers, locations, and depth. Once everything was in order, the custody of samples changed from our NRDA sample rep to the sample reps on the supply boat. This formal chain of custody is necessary because data from the samples could eventually end up in a court of law. As the supply boat pulled away, I looked at my watch – it only took us 1.5 hours to transfer four coolers of samples.

The Cajun Canyon Express alongside the Henry B. Bigelow for a supply transfer.

Our next “chore” for the day was getting more freshwater.  As I noted in an earlier post earlier, the ship cannot make water in the incident area, so we only have the water we left Key West with, and we’re getting low even with conservation measures. We ordered some water, and the water boat just pulled along-side. They will transfer 8,000 gallons of freshwater to the Henry B. Bigelow at a rate of 110 gallons per minute in about two hours.

We are getting our “chores” out of the way so we can be ready to enter the wellhead area once the “kill” operation is completed. The mud injection was completed yesterday, and they are currently cementing the well. From the surface it looks the same; about 20 ships sitting absolutely still five miles away. But I am sure there is a lot of activity under the surface.

Until we are able to enter the well head area again, we will continue water sampling and acoustic monitoring of the outlying areas.

Jon Hare

Chief Scientist

1:30 AM and the Gulf is Still Beautiful

It is a beautiful day. If you weren’t looking toward the 20+ ships and couple of rigs a kilometer away, it would seem like another hot, sticky summer day on the Gulf of Mexico.

I worked in the Gulf in the mid-1990s on the NOAA Ship Chapman and the late-1990s on the R/V Pelican. I remember long stretches of calm days, blue water (not a deep blue, but a light blue), and marine life: dolphins, whales, tuna, and more. I have seen all these things in within 1500 meters of the wellhead over the past three days. The release of millions of gallons of oil is an environmental disaster, and the problem is still with us. But even so, the Gulf of Mexico is still beautiful.

We are continuing our acoustic monitoring in the area around the wellhead. We have made 20+ passes over the wellhead in the past two days. From our cursory examination of the data and from the acoustic experts onshore, there has been very little change in conditions. There are acoustic returns in the water column – likely from methane gas – but the magnitude has not increased. The wellhead area is closed now for the static kill and it will be interesting to see what the acoustic data shows when we get back into the 500 meter zone.

Last evening, we started our water sampling effort. We cannot work inside the 1500 meter zone at night and we have used this time to acoustically map much of the area between 1500 and 3000 meters. Our plan last night was to go back to two areas of acoustic returns outside the wellhead, remap these areas, and collect water samples.

We are interpreting these areas as natural seeps – areas where hydrogen sulfide, methane and other hydrocarbon-rich fluid ‘seep’ into the ocean. We ‘see’ seeps as areas of acoustic returns that extend into the water column from the bottom. Some of these areas are persistence; identifiable every time we cross over them, while others are intermittent; they are sometimes there and sometimes not.

We made two conductivity, temperature depth casts (CTD), one to 1000 meters and the other to 1400 meters. A CDT instrument measures the temperature, conductivity, and depth through the water column. Conductivity is converted to salinity – how salty the ocean is. Temperature and salinity are basic oceanographic variables that say a lot about the source of water sampled.

We also have a dissolved oxygen and a color dissolved organic matter sensor. Obviously, the dissolved oxygen sensor measures oxygen in the water. The color dissolved organic matter sensor provides a measure of how much oil there is in the water. Two of the features that have been described for subsurface oil are an increase in colored dissolved organic matter (dissolved oil) and a decrease in dissolved oxygen; the argument being that bacteria are using oxygen to break down the oil.

Water bottles on the CTD can be used to collect water from specific depths. If we see a layer of water with increased color dissolved organic matter and decreased oxygen, we can close a bottle, bring the water to the surface and prepare the water for chemical analyses. The measurement of dissolved oxygen uses a Winkler titration and these can be preformed on the ship. The measurement of oil requires a gas chromatograph, which we do not have onboard. The water is poured into specially prepared bottles, put into a big walk-in refrigerator and then transported to shore in a small boat for analysis.

The first CTD cast was made over an area of blue water; no acoustic evidence of seeps. Unfortunately, we had problems with the winch and the CTD was not deployed all the way to the bottom. We did, however, collect water as the CTD was brought back to the surface. Once the CTD was on deck, the water chemistry team descended on it,  and collected the water from the bottles for the dissolved oxygen analysis and oil analysis.

The second cast was made over an area of a seep. The presence of the seep was confirmed using acoustics and then the ship tried to sit right on top of the location for the 2.5 hour CTD cast – it takes a long time to lower a CTD a mile and then bring it back. The ship drifted in and out of the seep, but we did get the CTD through the acoustic signature of the seep. Once on deck, the chemists descended again, and oxygen and hydrocarbon samples were taken.

We then moved to other seep location and conducted more acoustic surveys to pinpoint the location for CTD sampling tonight. The sun came up just as we were completing our acoustic survey, and we returned to the wellhead site. Since then, we have been circling all day monitoring the perimeter for evidence of leaks from the well (we have not detected any). We are also waiting for our chance to survey over the wellhead to evaluate the success of the kill operation.

Making Our Mark in a Crowded Field

Submitted August 1, 2010

The level of effort to end the Deepwater Horizon incident is impressive. We spent the day working within 500 meters of the wellhead; moving through a field of boats and rigs to collect acoustic data. Working here has made me appreciate the complexity of the problem even more.

Deepwater Horizon MC252 from the Bigelow wheelhouse

Rigs drilling relief wells. Vessels held stationary with dynamic positioning and controlling Remotely Operated Vehicles that are working 1 mile down. Ships passing through the field conducting seismic surveys to evaluate potential changes in the rocks and sediments below the ocean bottom. Boats carrying crew, groceries, water, pipe, and a myriad of other supplies. It is a work site of more than a thousand people and amid it all, we are driving back and forth collecting acoustic data.

Pretty sure I could throw a pass to a receiver on the Helix deck

The Bigelow’s officers and crew are doing an amazing job navigating through the wellhead area, moving between multiple ships to get the data that we need. Sometimes it seemed like we were close enough to throw something to the ships we were passing.

We made 10 or 12 passes over the wellhead and sent the acoustic data to shore for analysis and comparison with what was collected by the NOAA Ship Pisces earlier.

SIMOPS is planning for the static kill and once this begins, most ships including the Bigelow will be excluded from the wellhead area. We will stand by and wait to begin our acoustic surveys again once we are allowed back into the wellhead zone. But for now, we are collecting as much pre-kill acoustic data as we can, which means more driving back and forth of the wellhead navigating a fleet of other ships.

Jon Hare

Chief Scientist

At the Wellhead with Lots of Company

Submitted July 31, 2010

Deepwater Horizon wellhead on approach by the Bigelow

We started the day with the sight of ships on the horizon – a lot of ships. We had finally made it to the Deepwater Horizon MC 252 Incident site: About 1700 miles from Newport Rhode Island to the Mississippi Canyon- almost Boston to Denver.

Our plan for first day was to work from 1500 to 500 meters of the wellhead. That is one to one-third of a mile. This may seem like a lot of space, but given that there are three oil rigs and 10 to 15 ships in the area at any given time, the space feels pretty small. There are also a number of support ships outside of the 1500 meter zone.

Our goal was to perform acoustic surveys to look for gas seeps: either natural or wellhead-related. The acoustic data we collect is transferred to shore where it is processed and compared with acoustic data collected by other NOAA ships at the site during prior weeks. We really need to work within 500 meters of the wellhead, but this first day we wanted to get a feel for the ship traffic and communication protocols.

The morning started with a conference call with British Petroleum’s Simultaneous Operations (SIMOPS) out of Houston, the group that’s providing traffic control for the Deepwater Horizon site. All ships in the area called in.

The SIMOPS director took roll call and ships reported persons on board, time to evacuate, air quality issues, mechanical issues, safety issues, and plan for the day. Our first call was uneventful and after about 40 minutes we were ready to work. We had already submitted a daily plan to SIMOPS the day before, which was approved, but the conference call allowed all the ships to get an idea of what everyone else would be doing.

With our SIMOPS clearance, we started acoustic surveys. Our primary instrument is an EK60 splitbeam echosounder. The EK60 transmits sound at different frequencies and then receives the reflection of the sound as it bounces of things in the water: fish, the bottom, and bubbles. We have our EK60 set to 5 second intervals, which means it “makes” sound every 5 seconds and then receives the reflections, also called” returns”, as they bounce back to the ship. The strength of the return is a function of the size and composition of the material in the water. Water has very little reflectance, while a bubble has a lot of reflectance.

More specifically, our mission is to conduct acoustic surveys using the EK60 to look for reflections of bubbles in the vicinity of the wellhead. We examine the data in real time to identify areas of interest – lot of reflection near the bottom–likely gas bubbles. We use this information to design subsequent surveys. We also send the data to shore via a satellite link. Acoustic experts on shore then process and compare the data to previous surveys of the area. It is these experts who are best able to interpret the data we are collecting.

So …we spent the day surveying the north, east and south part of the 1500 to 500 m zone. We “saw” some remotely operated vehicles working near the bottom and umbilical cords connecting the vehicles to the ships a mile above them. We also detected several areas of interest and reported these to the acoustic experts on shore.

After 10 hours of surveying and maybe 30 miles of track line, it was time for our evening SIMOPS conference call: roll call, ship reports, and plan for the next day. We also submitted our plan for the next day electronically. Our first day working in the vicinity of the Deepwater Horizon site ended.

But just because the day ended doesn’t mean the work ended. We can’t work close to the wellhead at night – the risk of collision with all those ships is too great. So we set up for acoustic surveys a couple of miles away. Natural oil and gas seeps are reported from the area, so the purpose of our nighttime survey was locate these seeps and collect data to determine if there has been any change.

Working all day and all night is par for the course. The Bigelow generally works 24 hours a day; different people and different jobs have different schedules, but through the night things are quieter and fewer people are around. Come dawn, we would break our far-field acoustic surveys and move toward the wellhead, requesting permission to survey over it. But for now things are quiet.

Jon Hare

Chief Scientist