Wednesday, June 30, 2010

Deepwater Oil Spill - mud motors and PDC bits

Tonight’s post will largely deal with the development of two tools, the mud motor and the drill, which will allow John Wright to make the connection, discussed yesterday, between the relief well (RW) and the Deepwater Horizon well (WW). But first an update:

The swells from Hurricane Alex have reached the Deepwater Horizon site, and the hard connection between the Lower Marine Riser Package (LMRP) and the drillship means that the cap over the well is seeing some slight movement with the waves. This may soon have an impact on the collection efficiency. This is already suffering some impact due to weather – after reaching levels of about 25 kbd.
For the first 12 hours on June 30 (midnight to noon), approximately 6,085 barrels of oil were collected and approximately 4,145 barrels of oil and 24.9 million cubic feet of natural gas were flared.

On June 29, total oil recovered was approx. 25,220 barrels:
approx. 17,025 barrels of oil were collected
approx. 8,195 barrels of oil were flared
and approx. 57.4 million cubic feet of natural gas were flared

Oil collection volumes were lower on the Enterprise on June 30th due to lightening storms from 9am until 11:45am CDT
The major impact, however, is likely to come from the delay in the changing of the well cap, and the connection of another tap of oil from the well, through the kill line.

In today’s press briefing Admiral Allen noted this:
The conditions on scene at the wellhead right now are winds between 17 and 22 knots and we have a sea state of about seven feet. In the next 24 hours, we look for that to diminish slightly the wind to 12 to 14 knots and over the next 24/36 hours to have the wind drop—the sea state drop to about six feet.

The major impact on the operations out there right now have to do with hooking up the third producing vessel the Helix Producer, which was anticipated to have been done right about now but has been delayed because of the ability to hook up to the flexible hoses been prohibited by the sea state. But we are able to continue the production that’s going on out there and last night over the 24 hour period that ended at midnight we produced 25,000 barrel—over 25,000 barrels.
And while I am becoming more cautious over taking a lot of the Admiral’s remarks with a great deal of confidence, I think that when he gives numbers these are more likely to be correct. And thus we learn that:
The Development Driller 3 is within 16 feet of the well bore continues to go down 2 or 300 feet at a time continues to close the well bore. Put electrical sensing device down to check the magnetic field to find out exactly how far they are away. They’re in their third series of what they call these ranging activities.

And they’ll continue to do that over the next several weeks as they get to the optimal point where they can turn and actually intercept the wellhead.
(As I noted yesterday BP say they are only drilling 125 ft before running another test and they will proceed until they are 5 ft away).

Once the wave action drops below about 3 – 5 ft then the cap on the well will be replaced. They have to undo 24 bolts to do this and that will need almost a calm sea to get the old riser end off the well, and the new cap in place – since it has to be lowered into place from a ship on the surface. Once the new cap is in place, the risers for additional collection are also available for hook-up. The new connections already in place will also allow the vents on top of the existing cap to be closed, at least partially, as oil and gas are diverted to the Helix Producer. (The decision has to be approved by Secretaries Salazar and Chu, however, before it can be implemented).

One thing that I think is worth mentioning over the change in cap designs is that the new cap seals at the BOP. Thus when the mud starts to flow into the well from the bottom, it will also flow up the riser pipes toward the surface. Thus the additional gain in pressure from that height of a mile of mud – over the seawater pressure at present – will act to help raise the pressure at the bottom of the well and kill it.

The Admiral noted that the Jones Act will only come into play if those vessels which are skimming out in the Gulf need to flee to an American harbor during a Hurricane. This only affects the 4 or 5 foreign vessels that are actively working. The speed of Government action is, however, illustrated by his remarks that:
Out of the 68, government-to-government offers to date 35 appear to be equipment or resources that we could use. We’ve accepted nine of those offers already and 24 of those offers are being processed right now through the State Department for acceptance. This is an ongoing process has been from the start but wanted to give you an update here.

Of the 39 private offers, it looks like 30 of those are equipment or types of materials that we could use. Those have been provided to our folks that are out there acquiring whatever it is booms, dispersants, or skinny material and they become part of the broader source of supply that we’re pursuing in trying to resource our operation moving forward.
The Admiral is now retiring, and returning, pro tem, as a civilian employee.

Yesterday I mentioned the procedures that John Wright, who is in charge of drilling the relief well, had previously used, and described in his company brochure.

His company (later sold to Boots and Coots) also put out a primer on blowout control. One chapter of this dealt with the use of relief wells, and explains how the development of detection technology and kill fluids has made the technique more viable and effective. It is noted that build rates of 20 deg/100 ft are now available, positional accuracy of 5% of the standoff distance are achievable. The RW will be 5 ft from the wild well (WW) so that this gives a precision of measurement of 3 inches.

There is not that much more on the tools to make the connection, however, so let me very basically comment on how a mud motor, or to give it the more technical name, a turbine motor works. I am doing this anticipating that there aren’t that many folks that have gone through the Tech Talks that have covered these issues in the past, and so there will be a little repetition from the talk on down-hole motors in what follows.

The idea of putting a motor directly behind the drilling bit is not recent, the first Russian turbine drill was designed in the mid 19th Century however it required a number of stages before the design could turn out enough power. And the first patent for an American downhole turbine was granted in 1873.

For those who are not familiar with a turbine drilling motor, essentially it consists of a set of fixed turning vanes at the top of the motor (the stator vanes) which direct the flow of mud going down the hole to flow onto a second set of vanes (the rotor vanes) which are pushed around by the flow, causing the drive shaft to which they are connected to rotate.

Single stage of a turbine motor, showing the stator and rotor vanes (Baker Hughes)

By combining a series of these stages together into a multi-stage turbine considerable torque, and speed, can be passed to the drilling bit that is attached to the rotating drive shaft.

Connection of a turbine drive to a drilling bit (Boraisegypt)

Putting the motor at the bottom end of the drill string had a couple of other advantages. One is that it allows the hole to make angle, i.e. to turn in a tighter radius than if the whole pipe were rotating. While conventional rotary rigs can build angle at only 10 degrees per 100 ft, with a down-hole motor the angle can normally build at 13-15 deg per 100 ft, and John Wright has been able to increase this to 20 deg/100 ft.

The Russian idea took a while to catch on in the West and to his credit, a guy in Houston called Bill Maurer, had a fair bit to do with that. Time and technology have however moved on a bit since then, and Bill’s company was acquired by Noble Drilling Corp so I can’t pass on links to the firm.

With the advent of down-hole motors there is no need to have the complexity of joining 30-ft lengths of drill pipe together to deliver power to the end of the bit. This had always been constrained by the steel strength and joint limitations. Now that could be designed out, and the power could be delivered to the bit hydraulically through the mud, since this could be used to drive the motor.

Later motors have included positive displacement designs, such as the progressing cavity motors which Dyna-drill illustrates with an animated figure at their web site.

For those interested in relative performance, and the gains that technology can bring there is a case study available of a well drilled with a down-hole motor and PDC bits with a rate of penetration (ROP) of 93.5 ft/hr.

Turbine motors work best at higher speeds, but to create the chips and achieve effective drilling with conventional tri-cones, rotation speeds had, historically been slow. And the problem remained of creating the high thrusts across the bit that were required for this type of drilling, when the motor turned faster.

One answer came in response to a second problem. As the rocks that have to be drilled become harder, so the forces used to cut through them also up, causing a materials problem. The materials used to make the drill bits were either wearing out, or teeth were being broken out as the bits pushed through the rock.

Worn out bit (Stavanger Oil Museum)

Drill with inserts knocked out (Stavanger Oil Museum)

But until now we had tried to break the rock in compression by pushing the tooth into the rock but if, instead we dragged the bit across the rock without trying to chip it, in the same way as a metal-cutting bit on a lathe peels off a layer of metal, maybe we could lower the forces on the bit.

And if we used a diamond tool to do this, then while each diamond insert would only remove a very small amount of rock, we could impregnate a whole bit face with small diamonds ( much cheaper than the single stone you buy for the intended, since they are much smaller, and more common). These diamonds can be dragged over the rock face and slice off very thin layers, but can do so when moved at a very fast speed. Putting the two together meant that a new drilling concept could be developed, and a new drilling bit.

Diamond drilling bit (Stavanger Oil Museum)

The next development came about with the development of larger polycrystalline diamond compacts (PDC's or PCD's depending on your level of technical correctness). By making these larger diamond coated discs and setting them on the drill bit it was easier to circulate the mud so that it kept the diamonds cool. The diamond is a thin layer on the face of the disc, that is formed at extremely high temperature and pressure, at the time that the small cylindrical insert itself is formed from tungsten carbide powder. The cylinders, and their distribution can be seen in this typical bit layout.

Used PDC bit (Stavanger Oil Museum)

This is important since, if you get the temperature of the inserts (which might each be quarter to half-an-inch in diameter or more) above about 3-400 degrees, the diamond starts to soften a bit and wears faster. In this regard the design of these bits is still not perfect, but it has become better.

In particular PDC bits can cut through metal as easily as they cut through rock. And thus they have been used, for example as “junk mills” tools specially designed to cut up metal pieces that might, for one reason or another fall into, or break-off in, a well. It is this metal cutting ability that will be used in the Deepwater Horizon application.

The bit that will be used appears to look a lot like the one I illustrated last, and will be run into and along the old casing and cement, at a high enough intercept angle that it won't bounce off (greater than about 15 deg) but grind through both to open a window of access for the mud in the RW to flow into the WW and kill the well. This is the initial plan. If it doesn't work, for whatever reason, possibly not getting the RW into exactly the right alignment and distance, then the intercept could be carried out from the RW using the shaped charges on a wireline, that I mentioned in the earlier posts on the topic.

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Tuesday, June 29, 2010

Deepwater Oil Spill - making the connection

The Deepwater Horizon relief well is approaching the point where it will intersect the original well bore. At the moment production is being maintained through the existing riser remnant and overlying cap and LMRP. The latest figures are:
For the first 12 hours on June 29 (midnight to noon), approximately 8,475 barrels of oil were collected and approximately 4,130 barrels of oil and 28.7 million cubic feet of natural gas were flared.

On June 28, total oil recovered was approx. 23,395 barrels:
approx. 16,275 barrels of oil were collected,
approx. 8,175 barrels of oil were flared
and approx. 56.2 million cubic feet of natural gas were flared
As the well continues to descend there will likely be an increased focus on determining exactly where the two wells lie, one to another. This requires a process that pulls the drill string each time, and so progress is likely to be slow as the RW reaches the level at which the entry into the original well will be first tried.
Kent Wells has described the process. But he does not describe how the wells will be connected. And I will make a little more detailed description of a possible way of doing this, that John Wright has used before, at the end of the post.

Note that Kent Wells points out that the ranging runs do not start until the final set of well casing has been set. (And this was completed on June 19th). Once the casing has been set, the procedure calls to drill 275 ft of MD (measured depth), and then pull the drill.

The instrument package is then run into the hole with a Vector Magnetometer, which is mounted on a wire to carry it in and out (known as a wireline). The process of drill and test, using the Magnetometer, continued until the steel casing in the original hole had been detected.

The process is illustrated a little better in the video of the visit to the relief well team:

Once the initial well has been found the procedure changes. Now after the well has drilled down an additional interval (a distance decided by those monitoring progress) instead of pulling the string all the way out and running the wireline in open hole to find the casing, the bit is only retracted to the cased section, and the magnetometer package is wirelined down inside the drill string.

At present they have made two ranging runs, and have found the initial casing, so that then know that they were 55 ft from it, and they have 16 degrees to turn the well through yet to get it parallel to the original. They have decided that this “additional interval” will be 125 ft, and then they will make another ranging run.

But the process is now changed so that in the new run this will be where the instrument is run inside the DP (drill pipe) instead of pulling it to the surface. After making a measurement it is pulled back out on the wireline. And then the drill can advance the hole a little, it then is backed off the bottom, and the magnetometer again is lowered and locates the original casing, this is plotted and the process repeated. Only the wireline was pulled to remove the magnetometer from the well during drilling (to allow mud to the bit to cool it and remove drill cuttings).

Once the RW passes the original well it will be turned to drill parallel with it and drill down its own 10 1/8th inch hole until it reaches a point just above where the 9 7/8th inch casing liner ended at the bottom of the original hole.

With the new well 50 ft above this point, and 5 ft from it, the relief well will be reamed at the bottom using a 12 ¼” reaming bit to widen the well at the bottom.

A 9 7/8” steel liner will then be run into the hole and cemented into place in the relief well, running back up to the 11 7/8” casing that was set at the beginning of the process.

The relief well will then end 50 ft above the bottom of the 9 7/8” liner length in the original well and 5 ft from it. (Remember that there are questions as to whether the oil is flowing up around the outside of the steel tube inside this one, or up the middle of it).

Now what is interesting, and missing from the presentation, is how the connection between the two wells is made. There is also a little discrepancy over where the hole will be reamed and the 9 7/8” casing will be run to. In the animation it is shown as 17,050 ft (above) and in the visit to the rig, at 17,758 ft. (I think, based on looking at the log that that number should be 17,158 ft, for the top of the 7” x 9 7/8” casing, which is the problem length.

So the BP discussion ends with the RW 50 ft above, and 5 ft over from where the problem might be located (at the bottom of the lined well length) where the oil and gas may be seeping up the outside of the production casing and entering the well.

Let’s remember what the well liner and casing look like, down at the bottom of the hole.

So the question is, once the well is at the bottom of the lined section, are they going to:
a) try and drill down into the leaking zone below the last liner section, intersecting this to use the channels created to carry the mud from the RW into the original well.
b) Mill over to the liner segment of the well and through it into the annulus between the production casing and the liner, and try bottom kill from there.
c) Drill further down and over to mill through and access the production casing, and inject the mud into this to kill the well.

I suppose it depends on what they find at the point where they set the casing at the bottom of the next interval. (I had planned to talk about the bits they planned to use for the milling, but 5 ft is a long way between the two wells to establish a connection, though presumably this was the distance that has been used in the past when wells were killed this way. John Wright has previously done this by attaching a milling bit to a mud motor and drilling over into the casing and down along it. These are illustrations from a brochure of previous jobs:

And the illustration of the milling bit (which can make the cut in only a few seconds).

Incidentally the company is now part of Boots and Coots.

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Monday, June 28, 2010

Deepwater Oil Spill - closing in on the well

Well with Alex trundling off towards Mexico, the second area of concern having dissipated, and the two +3 earthquakes in Iceland being North of the island, or up around Loki, the worry over the impact of natural hazards can be set back just a little today. Which is helpful, given that the relief well is approaching the point where it might soon bring this sorry episode a lot closer to the end game.

Total recovery from the BP site has been relatively consistent in the immediately recent past:
For the last 12 hours on June 27 (noon to midnight), approximately 8,340 barrels of oil were collected and approximately 4,100 barrels of oil and 28.8 million cubic feet of natural gas were flared.

On June 27, total oil recovered was approx. 24,450 barrels:
approx. 16,275 barrels of oil were collected,
approx. 8,175 barrels of oil were flared,
and approx. 56.2 million cubic feet of natural gas were flared.

Total oil recovered from both the LMRP Cap and Q4000 systems since they were implemented is approx. 438,000 barrels. An additional 22,000 barrels were collected from the RIT tool earlier in May bringing the total recovered to approx. 460,000 barrels.

Connections for the first free standing riser have been completed and this will be connected to the Helix Producer – “a redundancy measure also taken under the direction of the Federal Government.”

The first relief well has now drilled to a depth of 16,545 ft – which puts it within about 150 ft of the point where the first connection may be tried, so I suspect the drill might be being turned horizontal. (Remember that it has to hit with an accuracy of about an inch). They may be steering it with a device called an Autotrak system where, just behind the drill bit (which is rotating – as are the main pipe segments – yellow in the picture below) a non-rotating piece of equipment is located (blue) that has three small rams that can push out against the well bore and direct the drilling head over in the direction required.

Autotrak assembly (Oil Museum in Stavanger) – you can see one of the pads pushed out as though it was pushing the head over.

This also implies that the last cement job was tested out satisfactorily, after the cement had set.

Read more!

Sunday, June 27, 2010

Coal Mining - robbing the pillars

In recent posts I have written about room and pillar mining, where the miners drive tunnels through the relatively horizontal coal seam, until they come to the edge of the property. Depending on the accuracy and honesty of the mine surveys, they then stop. I mention this latter because, on occasion, miners who later worked in an adjacent mine, thinking that they have plenty of room, have worked close to the boundary on the other side, and suddenly, and often tragically, have found that they were too close. Water or gas that had collected in the old workings flooded into the new ones, with usually fatal results. (The Quecreek Mine Rescue was an exception).

Once the mine has reached the boundary, there is still a lot of coal left in the pillars. If the mine tunnels are 15 ft wide, and the pillars are 45 ft wide and the coal is 6 ft thick, then using a rough rule that a cubic yard of coal weighs a ton, gives that the original tonnage between the tunnel center-lines, assuming square pillars, would be 800 tons (20x20x2). The pillar left contains 450 tons, so that the initial extraction only removed 44% of the coal and 56% remains in the pillars. So, providing that the mine does not have major surface construction that would be harmed if the ground subsided, the miner might choose to remove some of that coal, as he retreats back from the boundary. (Although David Kuchta will tell you of times when folk were less fussy about worrying about the houses on the surface).

This practice is known as “pillar robbing,” though to get away from the negative picture that this raises, it may be called “pulling” or “drawing” the pillars. Essentially the miners will start at the boundary and work back towards the shaft, removing coal from the pillars in a systematic pattern as they go. And if you pull out the supports that hold the roof up, then that roof will collapse into the opening beneath it.

This is where there is some skill and forethought required in planning how to mine out the pillars, and to control the way in which the roof breaks. If the pillars are pulled properly, then the coal that is left, because some is, will crush sufficiently slowly that the miners can have enough warning to be out of the way, and it will control the way that the roof breaks.

The process can be illustrated by first showing the layout I used earlier for the development of the mine:

Overview of a working room and pillar section

And then look at a mining plan after the mine has pulled most of the pillars from a section.

With 80% extraction the mine is now only leaving 160 tons of coal behind in the fenders or stumps. Fenders are usually the larger pieces of pillars that are left along the edges of the path the machine must move along, stumps are the residuals in the body of the pillar.

As the miner removes the coal, to keep the operation safer, while the coal is being removed, wooden props used to be installed that would hold the roof in place.

That practice, with the men under unsupported roof is no longer used. Now the coal is extracted using, increasingly, remotely operated mining machines, with the supports more closely located around the mining area and increasingly being hydraulic.

Pillars can either be mined very simply, by cutting into the side of the pillars left in initial mining:

Simple pillar removal sequence SME handbook

The small black circles are where the props (historically wood but now hydraulic props) are located.

Pocket and wing mining – the pockets are removed in sequence, the wings are left to hold up the roof.

In stronger coals or where the roof is better more of the coal can be removed.

Sequence of coal removal (SME Mining Engineering Handbook Vol 2)

The reason that the props are located close together at the edges of the remaining rooms, is that the roof layers above the area will start to break after the coal is removed. By establishing the props along the edge of the pillars the breakup from the previous coal removal will be stopped at the edge of the existing pillars.

The roof breaks into fragments as it falls, and will bulk into the space left by the coal removal. This bulked up rock provides some support to the roof overlying the area where the coal is then removed in the next sequence of mining. And so the process retreats.

It is not as effective as getting all the coal out, and can lead to more difficult problems at the surface than an alternate method of mining called longwall, and we’ll come to that next. But pillar robbing requires a great understanding of the geological conditions before it can be safely carried out. Unfortunately when this is not the case then we get disasters such as that at Crandall Canyon.

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Saturday, June 26, 2010

Deepwater Oil Spill - a little more progress

Travelling today we discovered that all the hotels in Urbana are full, due to a softball tournament, so this will be short. One thing that a couple of relatively gentle Hurricane seasons lulls us into forgetting, is that when the nucleating storms start to crank up, they can come quite regularly for a significant period of time. Back in 2005, for example, the National Hurricane Center ran out of normal alphabetical names for the storms. I mention that because, while Alex, the first storm of the season, is now landing and crossing the Yucatan Peninsula, there is already another area of concern forming in the Atlantic.

Back in the Gulf,
For the first 12 hours on June 26 (midnight to noon), approximately 7,570 barrels of oil were collected and approximately 4,070 barrels of oil and 28.3 million cubic feet of natural gas were flared.

On June 25, total oil recovered was approx. 24,550 barrels:
approx. 16,340 barrels of oil were collected,
approx. 8,210 barrels of oil were flared,
and approx. 54.5 million cubic feet of natural gas were flared.

Total oil recovered from both the LMRP Cap and Q4000 systems since they were implemented is approx. 391,000 barrels. An additional 22,000 barrels were collected from the RIT tool earlier in May bringing the total recovered to approx. 413,000 barrels.
And your Federal Government want you to know that they are in charge:
BP has finished installing the first free standing riser, which has greater survivability than a fixed riser and will be connected to a third vessel arriving at the site of the wellbore next week, the Helix Producer—a redundancy measure also taken under the direction of the federal government.
The relief well has reached a point where the well needs to be cased and lined, and that is in hand. As the depths get closer to that of the original well (RW at 16,400 ft original well 18,000 ft) I suspect that there may be a little more care than usual taken to ensure that this cement job is good. And once that is complete, then as the drill begins to advance further the “ranging”operation will continue.

Given stated concerns over the use being made of foreign aid, the Coast Guard Joint Command also wants you to know that
To date, the administration has leveraged assets and skills from numerous foreign countries and international organizations as part of this historic, all-hands-on-deck response, including Canada, Germany, Mexico, Netherlands, Norway, the United Nations’ International Maritime Organization and the European Union's Monitoring and Information Centre.
And finally (in more senses than one) the Solar Car Race is over. The results for today were:

Results for the last stage of the Solar Car Race.

These numbers should be added to those after the second stage. They show that Michigan won the race. Minnesota was second and the German team from Bochum third.

And so, as the ROVs work to attach new risers to the well, and prepare for a cap change later in the week, we will move on.

Sorry that the temperature data is missing again this week, but now that the RAW data is available I would like to more closely look at it before putting another post up on the topic.

Read more!

Friday, June 25, 2010

Deepwater Oil Spill - Weather looks worse, as the solar race goes on

The weather situation in the Gulf is getting a little worse, as the National Hurricane Center has now classified the wave I have been writing about recently as Tropical Depression 1, with a second area of low pressure forming further out into the Atlantic.

Once the storms are identified this way, then the NHC begins to provide tracking information, and this is the current prediction for the storm track. I have put a red square where the Deepwater Horizon well is roughly located.

The white zone around the path shows where winds will rise to over 50 knots. At the briefing today Admiral Allen noted that when the winds are predicted to reach 40 knots in the area, then 120 hours before that occurs the rigs will be disconnected and moved to a safe area.

Also in the briefing the Admiral explained the location of the initial well and the relief well (RW) (one relative to the other) in a little more detail. Now that the initial location of the well has been established, the RW is drilling back downwards. But every so often it will stop and:
This is where they withdraw the drill pipe and put down an electrical cable into the end of the wellbore, and they put out an electrical signal, and they actually could pick up the magnetic field around the wellbore. This tells them how close they are getting.

They have made contact with this electromagnetic field. What they will do is continue to drill down in short intervals, withdraw the pipe, put that sensing device down, and slowly close on the wellbore to the point where they're ready to do the intercept drilling.

This last part takes some time, because they only do several hundred feet at a time, withdraw the drill pipe, and then put the sensor down to figure out how close they're coming. After a series of these readings, they can have a very precise idea of how close they are to the wellbore and then how to actually turn the drill in and make the intercept. But then we'll get much slower, because they have to basically drill, withdraw the drill pipe and put the sensor down.
They also have a vessel standing by that's full of mud on the top, in the event they get really close, they could potentially knick the wellbore they could actually put mud down to control any hydrocarbons that might come out.

Regarding the longer-term containment, we should by next week have the additional vessel in place to start producing off of the kill line. That's the other line that's available to bring oil to the surface. That will bring us the three production vessels and the 53,000-barrel capacity we were looking for by the end of June.
In the change to a new cap that is planned for next week, there are three different designs that are being considered for installation. The ROVs are currently hooking up the hoses to the new distribution system that will ultimately feed four risers.

The recovery operation has returned to collecting about 24 kbd:
For the first 12 hours on June 25 (midnight to noon), approximately 7,870 barrels of oil were collected and approximately 4,230 barrels of oil and 27.5 million cubic feet of natural gas were flared.

On June 24, total oil recovered was approx. 23,725 barrels
• approx. 15,785 barrels of oil were collected,
• approx. 7,940 barrels of oil were flared,
• and approx. 54.7 million cubic feet of natural gas were flared.

In the solar car race, the final staging stop before the final tomorrow has been reached in Normal, OK with the official times for the first two stages being posted at the race website .

The current times are (unofficially from the Michigan web site

Michigan . . .25:15 (hours and minutes)
Minnesota . . . . ..27:27
Bochum . . . . . . 27:37
Stanford . . . . . . 28:52
Missouri S&T . . 29:40
Calgary . . . . . . .30:21
Kaohsiung . . . . 32:48
New Platz . . . . . 41:37
Kentucky . . . . . 42:00

And these are the only cars to complete the third stage.

Posting will be a little shorter over the next few days as we drive East, but I will try to at least include the daily oil production, the end of the solar car race and further developments if relevant in the weather (but hopefully not for the volcano).

Read more!

Thursday, June 24, 2010

Deepwater Oil Spill - Future storms, current production, the relief well and the car race

Perhaps the most worrying thing that has happened in the past 24-hours is the change in designated color of the storm moving through the Caribbean towards the Gulf of Mexico. It is not that long ago that the National Hurricane Center had colored it yellow, but now, more ominously it is red. (Which indicates a greater probability of bad weather). This is unfortunate given that it appears that almost all the oil from the well is now being captured.

Storm potential over the Gulf - 24th June

The discussion of this developing problem will, however, become more pertinent once the storm enters the Gulf, and so I will leave the topic until then. In the meanwhile the collection of oil from the cap seems to have returned to the status before the cap was removed.
For the first 12 hours on June 24 (midnight to noon), approximately 7,215 barrels of oil were collected and approximately 4,040 barrels of oil and 27.2 million cubic feet of natural gas were flared.

On June 23, total oil recovered was approx. 16,830 barrels:
• approx. 8,300 barrels of oil were collected,
• approx. 8,530 barrels of oil were flared,
• and approx. 36.7 million cubic feet of natural gas were flared.
However when the cameras on the ROVs are examined the picture is a little different from earlier.
The camera on the Enterprise ROV2, for example at 9:50 pm is showing no oil leaking from under the cap.

View of the cap 9:50 pm June 24, showing no leak on the Enterprise ROV side of the cap.

In contrast there is still some volume leaking on the Skandi ROV2 side of the cap – but the body of the cap can be clearly seen, suggesting that the draw-off of the oil and gas is reaching the totality of the flow.

View of the cap and leak from the opposite side (Skandi ROV2) where the body of the cap can be clearly be seen, suggesting that almost all of the flow is now being captured, since the oil and gas leaking out are much reduced in flow.

However both these views do not show what is happening at the top of the cap, where the vents are that allow oil and gas to escape from the top of the cap. But this suggests that the well flow is coming more under control, and that as the four new riser pipes are put into place, and more flow is extracted through the choke and kill lines, that the leak into the Gulf can be reduced to almost zero, which will then happen as the new cap is put into place next week.

I wanted to clarify a little more what I am referring to as the End Game for the drilling of the relief wells. In his remarks the other day, Admiral Allen said:
they're going to try and intercept somewhere around between 16,700 and 17,000 feet. We will confirm that for you and put out a statement tomorrow. They don't have to go clear to the reservoir, which is at 18,000 feet, and what they're going to do is they're going to close in and very slowly close to that point where they will then drill through the wellbore casing, and if they need to, drill through the pipe itself. But you are right; they'll be slightly above the level of the reservoir.
And subsequently he talked about “ranging” to find the exact position of the original well. To do this the relief well has come in relatively horizontally and electrical pulses have been sent down the casing of the original well. I believe that the connections to allow this were being monitored by the Skandi ROV1 until earlier this evening when it moved away.

Skandi ROV1 showing the electrical connections (lhs) to the plate allowing the electrical pulses to be transmitted down the casing.

As the electrical current flow down the casing it will (as Faraday demonstrated, as you no doubt all remember from High School Physics – grin) generate a magnetic field around the path. By including the appropriate instruments on the relief well drill string, it is possible to therefore locate the original well with a much higher degree of precision than from the original dead reckoning of the well location.

Once this has been done, then the well will swing back down to vertical and drill down until it is close to the desired depth, when it will again turn horizontal and drill over to intersect the well. At this point they hope to hit on the centerline of the casing so that they can mill through it, although should they be slightly off they can (as I noted earlier use penetrating charges to create the flow path for the mud to enter the well.

Projected future path of the relief well

On a lighter note I went over to the start of the solar car race today, and there was a little excitement, first the car from Bochum had a tire problem and could not leave the gate on time, and thereafter a second car had a problem just after leaving the gate. Much excitement for a few moments, and then the Germans had their car fixed and were away about 15 minutes behind the pack.

The next stop was Alton and the times for the cars making it there are reported to be:

1) Michigan . . . . 20:27 (hours and minutes)

2) Minnesota . . . . 21:33

3) Bochum . . . . .22:29

4) Missouri S&T 24:31

5) Calgary . . . . 24:43

6) Kaohsiung . . 27:03

7) Kentucky . . 35:53

The cars had made it to Alton by 2 pm, (first 5 cars in Michigan, Minnesota, Stanford, S&T, Germany.) but there was some problem with the road, because of earlier flooding. Following that check-point the cars have continued, with Missouri being close to Springfield, IL. There is a rumor that Minnesota has passed Michigan. Northwestern have yet to make Alton and are 260 miles from the next stage stop, at Normal, IL, which they need to reach within the 7 hours of racing tomorrow.

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Wednesday, June 23, 2010

Deepwater Oil Spill - Problems with the LMRP cap

BP issued a press release this morning that read:
NEW ORLEANS -- This morning at approximately 8:45 a.m. CDT, a discharge of liquids was observed from a diverter valve on the drill ship Discoverer Enterprise,which is on station at the MC252 well-site. As a precautionary measure,the lower marine riser package (LMRP) containment cap system, attached to the Discover Enterprise, has been moved off the Deepwater Horizon's failed blow-out preventer to ensure the safety of operations and allow the unexpected release of liquids to be analyzed.

Capture of oil and gas through the LMRP cap is therefore temporarily suspended until such time that the cap can be re-installed. Capture of oil and gas through the BOP's choke line to the Q4000 vessel on the surface continues.

LMRP cap floating free 4 pm June 23, 2010 (Enterprise ROV2)

UPDATE: The cap was replaced at around 6:30 pm and appears now to be working as before the event. The standings in the Solar Car race have been added to the end of the post.

Unfortunately the severe weather in the area today is not helping the effort either.
Due to severe weather conditions expected across southeast Louisiana today, June 23, regularly scheduled cleanup and response efforts may be impacted/halted as weather systems move through the area. These efforts include controlled burns, dispersant flights, and booming operations. Source efforts and some skimming vessels may be operating as long as conditions do not exceed their operating limits. Protective boom is in place along many miles of Louisiana’s coastline. Crews will resume cleanups as soon as safely possible. Safety of all personnel is important to the success of this operation.
At a press briefing in Washington on the event Admiral Allen blamed the event on an ROV hitting one of the valves on the vent at the top of the cap and causing it to close. With the vent closed the pressure under the cap would increase (since the flow would have a smaller area to escape through). That increase in pressure was enough to reverse the flow through one of the lines that send warm water down to the cap to keep it warm enough that hydrates don’t form.

It appears, from Joel Achenbach's Washington Post report that oil and gas was found coming out of a line that was pumping the water down, which raises a little question over the flow circuit being used that would allow that to happen? That discovery led to the cap being removed from the well for inspection. Any gas outlet at the surface would pose increased risk to those running the operation and had to be dealt with immediately.

The current plan is to replace the cap later this afternoon, presuming that the blockage has been removed. Unfortunately, without the pressure gage recordings from inside the cap it is not possible to know if the pressure build-up was gradual, which could be explained by this deposition of material in the flow path, or if it was a step-function which would more likely result if an ROV had nudged a valve closed.

As I mentioned earlier the alternate hypothesis is that there has been some crystal growth within the flow path through the cap, which caused crystals to grow, constricting the channel and thus raising the pressure in the cap itself. The pressure jump cannot have been too rapid if the indication of the problem came from the backup of oil and gas out of a water line. And crystals can form either quickly, in large size, or more slowly and insidiously.

Barium Sulfate Crystals growing in a 3-inch I.D. pipe that carried oil from the deposits under the North Sea. (Scale is in cm) (Growths of this size can occur in less than 24 hours).

That having been said, and recognizing that Occam’s Razor may well cut my hypothetical throat one of these days, the transcript of the press conference is now available. The Admiral clearly blames the ROV for the incident
Out of abundance of caution the Discover Enterprise removed the containment cap with the riser pipe and moved away until they could assess the condition.

They have indicated that the problem was a Remotely Operated Vehicle that had been around the (inaudible) package that bumped into one of those vents that allows the excess oil to come out. They actually closed it thereby creating pressure and the backflow potentially off the water vent.

They are checking the containment cap right now that there are no hydrates in the containment cap. They will attempt to reinstall the containment cap and begin producing later on today. If there are hydrates they will probably have to rerun the pipeline, and that will take a considerable amount longer.
At present it appears that they are lowering the cap back into position. The specific event was described as follows:
My understanding was they noticed there was some kind of a burp in the line where there was either natural gas or some reason. They thought they had product—or hydrocarbons coming up through the water line that's usually meant to carry hot water down, which is to heat the pipe, as you know to do away with the hydrate problem.

When they thought that that line might have been compromised, or they have the chance that they might have hydrocarbons coming up through that vent into the Discover Enterprise, which is flaring right now, over an abundance of caution they elected to remove the cap and move the riser pipe and the cap away.

When they moved it away then it's open to seawater. And they said if there is any product there you have the chance for hydrates to form. So before they decide to move it back in they have to check and see if there are any hydrates there. If there are hydrates they are probably going to have to pull the drill pipe and reinsert it once the hydrates are cleared.

And again, the initial indications were that one of the vents, which is allowing the oil to vent so the cap will stay on will somehow might have been dislodged by coming in contact with our ROV. But I think they are trying to validate that right now. They do know that one of the vents was shut when they set the second ROV down to take a look. That's all we have right now. We're continuing to look into it.

But then there was also this
they found this out after the fact when they set their ROV down after they had removed the containment cap that it appeared that one of the vents had been closed. Now the assumption is that was a result of an ROV bumping into it and actually closing the vent. We don't know that for sure. I think we're still developing the facts associated with it. I don't think it's any problem in putting on an exact timeline when we get all that stuff together.

The Admiral also updated the schedule for drawing oil from the BOP through the kill line. The riser to carry that has been installed, and they are now hoping to have that hooked up to a second vessel by next Tuesday. This will increase the production capacity from the well to 53,000 bd.

Given the concern that has been expressed about hazardous vapors being given off over the clean-up site, the Admiral also brought an OSHA representative to the meeting, and he noted:
We have been taking samples again, of worker chemical exposures. Again, on the beaches, in the swamps, on the boats, everywhere that workers are. And I will just let you know, we can discuss this a little more, that we have found no exposure levels to any chemicals that are of any concern.

The main problem we've been seeing down there, the main concern that we've had for worker health and safety has to do with heat. As you know, people are working in very high heat conditions. Very often they are also working with Tyvek suits with chemical protective suits, gloves, which exacerbates the heat problem.

Finally there was this interesting teaser about the possibility of running the production from the well to an existing platform.
I believe BP is in discussion with other industry producers that have rigs in the area that might be useful for that. I don't think they concluded those yet. I just mentioned it yesterday because I was asked about whether or not there were any redundancies or any recourse if we had a hurricane or heavy weather that allowed us to move—or required us to move all of the vessels from the scene.

This would be one way if you are actually connected to another drill site, you would not have to rely on service vessels.
There is more on what would be involved at Upstreamonline (who asked the question).

The update on the solar car race, with the teams resting in Rolla overnight, and leaving at 9 am in the morning:

1) Michigan . . . . .15:48 (hours and minutes)
2) Minnesota . . .17:06
3) Bochum . . . . . 17:28
4) Calgary . . . . . .19:08
5) Stanford . . . . . 19:23
6) Missouri S&T 19:47
7) Kaohslung . . . 22:01
8) New Paltz . . . 25:27
9) Northwestern 27:43
10) Kentucky 28:05

And as I drove home from work car #5 the entry from Illinois State, rolled past me and on to the finish line.

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Tuesday, June 22, 2010

Deepwater Oil Spill - Entering the old well, and the solar car race

UPDATE 3 pm: I have looked at the fuller comments that were apparently made at the phone conference this morning about the need to remove the plug from the Blow-Out Preventer (BOP) (sorry I missed it since I was watching MO S&T pass Calgary in the solar car race) and I am not sure that it was necessarily an ROV bumping the cap that closed a valve and caused the problem. For those reading earlier posts I have commented on how, even in fast flows, precipitation can close nozzles, and back on May 10th I posted pictures showing how precipitation can close pipes and nozzles. The blockage that caused the removal of the cap may thus have a similar cause, and can, in the short term possibly be remediated best by just pulling the cap to the surface, cleaning it and the feed lines and sending it back down. I'll put up a separate post as soon as I can check some more, and then get it written. end UPDATE

As the fleet above the Deepwater Horizon well begins to build, the new daily production total for oil has almost reached 26 kbd.
For the first 12 hours on June 22 (midnight to noon), approximately 8,195 barrels of oil were collected and approximately 5,045 barrels of oil and 27.2 million cubic feet of natural gas were flared.

On June 21st, total oil recovered was approx. 25,830 barrels:
• approx. 15,560 barrels of oil were collected,
• approx. 10,270 barrels of oil were flared,
• and approx. 52.2 million cubic feet of natural gas were flared.

• The fleet above the well as the collection system begins to change.

The Helix Producer will be collecting oil from the BOP and feeding it to the Loch Rannoch for storage. Note the preparation of underwater dispersant tanks, in case the fleet has to abandon the site due to an approaching hurricane. Speaking of which, the picture of the Gulf hasn’t changed much since yesterday, questions on the possibility of a hurricane being formed by the end of next week remain in the air.

BP is giving the money from the sale of the oil to the National Fish and Wildlife Foundation, with the first check (for $5 million) already on its way.

I was asked today why there need to be two different ways of getting into the casing at the bottom of the existing well. And why the relief well had to make a bend to come into contact with the original well at right angles. Well the reason that this is so, is that the initial intent is to use a milling or drilling tool to go through the steel casing. Now the casing is not that large in diameter, and so the surfaces curve away from the closest point of contact. As a result, if the relief well does not come in so that it is aligned with a diameter of the old well, then it will strike the edge of the casing at a very shallow angle.

The analogy that I used was to consider that you want to drill a hole through a piece of wood. Normally you set the drill up so that it drills down perpendicular to the wood, and the hole is made. But if the drill was set at a very shallow angle to the wood (say 10 degrees or less) then as you tried to push the drill into the wood, it might bend along the wood surface instead. Push hard enough and you will break the drill bit. Starting a hole in rock is often referred to as “collaring” the hole. In jack-leg drilling, which often occurs on a relatively rough rock surface, the drill bit is held against the rock with one hand, while the other slowly starts the drill, until the “collar” is established. It is very difficult to establish a collar on a very shallow angle, particularly if the drill bit is at the end of a three-mile long piece of pipe.

This is why, if the relief well drill comes up against the side of the casing, and it is not aligned so that it can drill into the old well without glancing off the casing, that the crew has another string to their bow. (And this is taken from an earlier Tech talk on Completing and Perforating a Well)

And this is where Her Majesty's Explosive (HMX) comes in. Small, specially designed, explosive charges, known as shaped charges are now put together into specifically designed charge packages, and lowered down into the well into the completion zone.

Arrangement of shaped charges (the yellow cylinders) – when the explosive goes off the cones collapse and small liquid metal jets shoot out of the open end, through the casing, concrete and into the rock, creating a channel. (Core Labs)

Here they are detonated, sending small jets of metal against the wall of the casing and perforating the steel and concrete into the surrounding rock. There is an animation that shows the jet being produced (see also information here) .

Representation of shaped charges firing and penetrating the casing, cement and wall (OSHA

As I have described it, this normally gives the passage for the well to flow out of the rock and into the well bore. In this case it has, instead, opened a path from the relief well into the well, rather than the reverse. It will be through these vents that the high density mud will be injected into the well to start the kill.

Looking at the ROV cameras tonight just as I go to post this it seems as though they are starting to hoist the old broken riser to the surface, unless they are examining the riser that is currently coming out of the Enterprise – but this has been embedded in sediment, and so is likely to be the old riser. Seen through Enterprise ROV 1). The flow out of the bottom of the LMRP cap continues to get less. I can now see considerably more of the wall of the cap through Skandi ROV 2 than I have been able to see in the past, because the cloud of oil and gas is diminished.

For those interested in Iceland, there was a 3-point trembler up by Loki but there is something of this size several times a month, and otherwise the island is relatively calm.

And as for the solar car race (and I might have some pictures tomorrow) there has been a little change in the order. The cars raced to Jefferson City – where they arrived over the course of the afternoon, had to wait for a while and then the leaders took off for Rolla – where they should arrive at about 10 am in the morning. The current order at the Jefferson City checkpoint is unofficially the following - times are total driving time to Jeff from Broken Arrow:

1) Michigan 12:18
2) Minnesota 13:12
3) Bochum 13:21
4) Calgary 14:30
5) Missouri University of Science and Technology 14:58
6) Stanford 15:312
7) Kaohsiun 16:51
8) Northwestern 22:17

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Monday, June 21, 2010

Deepwater Oil Spill - The Admiral on casing and connections, and an update or two

I am following a number of different events this week, and so today is as much a set of updates, as anything. Firstly the oil in the Gulf.
For the first 12 hours on June 21 (midnight to noon), approximately 8,410 barrels of oil were collected and approximately 5,015 barrels of oil and 25.3 million cubic feet of natural gas were flared.

On June 20, total oil recovered was approx. 23,290 barrels:
• approx. 14,570 barrels of oil were collected,
• approx. 8,720 barrels of oil were flared,
and approx. 48.3 million cubic feet of natural gas were flared.

Total recovery was slightly down on June 20 due to shut-ins from a lightning storm in the area of the Enterprise and Q4000 heading changes to accommodate wind shifts.
One of the concerns in the Gulf relates to the arrival of a hurricane, and the National Hurricane Center is showing the development of an area of low pressure that could cause problems later in the week. It has changed from yellow to orange in the past day.

National Hurricane Center

Admiral Allen held a telephone conference call today. In this he mentioned that the deeper relief well has now reached 10,677 ft. They intend sending electrical pulses down the casing of the existing well (WW), which will induce an electro-magnetic field that will help locate it and allow the relief well (RW) to be steered towards it. This will start about now, and will allow a much more accurate estimate of position than they now have. The RW operation is currently scheduled for the second week of August

Given concerns over the integrity of the borehole, Admiral Allen specifically noted (in response to a question from the AP) that during Top Kill they had evaluated the highest pressure that they could use in injecting mud, without impacting the integrity of the casing. When they reached that pressure, without being able to kill the well, then they stopped the operation. But that did not damage the wellbore, and though there may be a problem with the wellbore near the top there is no way to check it, and thus they will rely on the bottom-up filling with mud. This will exert less pressure on the casing, and if, at that time, there is a casing failure it will be with the well full of mud, and thus of less consequence. It is also why they don’t want to cap the well at the surface now. They are capturing the oil and gas, and the RW will be able to perform a safer kill.

Apparently the vents on the top of the LMRP cap are still open, and the 23,000 plus bd that is being produced does not count the amount that is still being vented. However they are bringing in another vessel so that they can tap into the kill line out of the BOP (they are currently only producing through the vent and the choke lines). That will allow an increase in volume collected to a capacity level of 53,000 bd sometime next week.

Following the tests on unbolting with the ROVs the new plan is to unbolt the current cut riser segment and then bolt the new cap onto the top of the BOP. That will then produce through 4,000 ft-long flexible risers (rather than the current rigid pipe) and should be in place by the middle of July. (With a capacity at that time in the 60,000 to 80,000 bd range). This will give the flexibility of totally sealing the end and directing the flow up the risers. BP has been tasked to put instruments that will measure flow into the new cap. The current intent is to carry this change through in the next 7 – 10 days.

He noted that there is no sign of ongoing erosion, and that the BOP is tilting at an angle of 10 - 12 degrees.

In regard to the fielding of the suction barges he said that the Coast Guard had carried out a safety inspection and found some safety issues with electrical grounding, and the barges were kept in port until those had been fixed. Which they now have been, and the barges are being used.

Two different procedures are also now being described for connecting between the RW and the WW. In one option the RW will intersect the well, and break through the rock wall of the well. Then a path will be milled through the casing to inject mud to fill the well, before pumping in cement, at the bottom of the WW to totally kill production.

If there are problems with the connection, and it is not a good intersection, then perforating charges will be used to penetrate between the two wells and provide the pathways for the mud and then the cement. This process also allows the area around the bottom of the RW to be separated from the main well with a packer, if it is needed, as extra protection.

To complete the updates for the evening: The Solar Car race had a slight change in order as they reached the Topeka checkpoint: (The times taken to get there from Broken Arrow are, in hours and minutes)

1) Michigan 7:25
2) Minnesota 7:50
3) Bochum 8:05
4) Calgary 8:41
5) Missouri S&T 9:21
6) Stanford 9:50
7) Koahsiung 10:31
8) New Paltz 11:44
9) Kentucky 12:30
10) Northwestern 13:22

Iowa and Texas-Austin are still in the race. After getting to Topeka the teams rested, and then tomorrow will leave Topeka and head, via Jefferson City, to Rolla, where they will rest on Wednesday evening.

And for those who wonder about the volcanoes in Iceland, the areas of concern are, at least for the last few days, relatively quiescent.

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Sunday, June 20, 2010

Deepwater Oil Spill - Improving the Clean-up

Flow recovery update from the Gulf:
For the first 12 hours on June 20 (midnight to noon), approximately 6,790 barrels of oil were collected and approximately 4,280 barrels of oil and 23.2 million cubic feet of natural gas were flared.

• On June 19, total oil recovered was approximately 21,040 barrels:
• approx. 11,050 barrels of oil were collected,
• approx. 9,990 barrels of oil were flared,
• and approx. 43.4 million cubic feet of natural gas were flared.

One of the more innovative recent technical advances that you have likely never heard of is called Hydro-excavation. It combines the use of a water stream of the sort you find at a car wash (i.e. 2,000 psi water at about 2 gpm) with a vacuum hose attached to a vacuum truck. It turns out to combine into a new tool that is quite effective for disaggregating soil and removing it to leave a relatively dry cavity down to significant depth, quite fast. It has a lot of advantages if you are excavating in an area where there are fiber-optic cables and other underground conduits that might take unkindly to the use of a back-hoe, (Including gas lines).

I mention this, because there is a certain amount of the clean-up now going on in the Gulf that can be done with waterjet lances, and some parts of the spill can be cleaned up with suction hoses. (And I have some experience with both, courtesy of helping in the development mentioned in the first paragraph). One of the classes that I have taught involved the use of pressure washers in a demonstration laboratory that supported the class lectures. So I thought I would take a moment to mention some of the things that need to be considered when using pressure wands and suction hoses.

The first obvious, but neglected point, is that the operator rarely can judge exactly where the tip is relative to the surface being cleaned. This is actually quite critical because the average pressure wand comes with a fan tip on the end. The tips come with different angles of dispersion of the jet, and having photographed a fair number, most jets are about 5 degrees broader than the jet pattern stamped into the nozzle. The second point is the one that is usually missed, but which relates to the distance of the nozzle from the surface.

When the jet comes out of a fan jet nozzle, the shape of the nozzle forms the stream into a sheet that gets wider with distance. Because the volume of water coming out at one time doesn’t change, the jet therefore gets thinner the further that it gets away from the jet.

Flash Picture of a fan jet

With a typical nozzle (usually called a tip) the sheet gets thin enough somewhere between 2 and 4 inches that the sheet perforates, and just as with a balloon when it pops, the material pulls back from the hole. In the case of the water sheet, this creates circles of larger droplets that continue to move forward. It is at this point that the jet is at its most effective, in many applications.

However, those droplets that are moving originally at about 550 ft/sec are moving into air that is relatively stationary. It breaks these large droplets up and decelerates them over the next couple of inches. As a result, the jet becomes virtually powerless within about 6-inches of the nozzle. (The distance varies with nozzle manufacturer, design flow rate and operating pressure – but that distance is typical). If you hold the nozzle further away from the target than that you are merely getting the surface wet, and not moving anything but surface dirt.

The problem that you, as an operator, have is that it is very difficult to judge that 6-inches. (Making it easy to “catch the student in error” at the beginning of the lab and reinforce the lesson). So the simple way to resolve the problem, is to touch the target surface before you start, position your feet accordingly, and then back the lance off a little and you are likely to be much more effective.

Having cleaned a wall of my house with an 18-ft extension lance to the normal pressure washer last week, I can also add that trying to maintain a 2-4 inch standoff while holding the lance above your head is an art that has to be learned.

OK, now the next problem is that most of the material being removed is going to be some form of hydrocarbon (oil. Oil emulsion or something similar). Some of these are quite sticky and hard to remove with just water pressure. In this case if the water is heated to about 185 deg F it will cut through and remove those coatings a lot more easily than at a lower temperature. You don’t want to heat it all the way to steam, since that loses the pressure of the jet at the nozzle too quickly, but with hot water the range can be extended.

One other way to extend the range is to use a spinning round jet nozzle (sometimes called a 0 deg tip). There are a number of these on the market and the cone of the jet is created by rapidly spinning the cylindrical jet that comes out of the nozzle. Depending on the quality of the nozzle (and diameter and pressure) these can increase the jet range to a foot or more. If you work out the amount of energy and water required to clean a surface both ourselves and some folks in Germany have shown that using this rather than a fan-jet can drop the amount of energy and water that you use to clean that surface by up to 90%.

The final point I want to make deals with the use of suction hoses. These are now appearing more frequently in some of the locally made systems being fielded along the Gulf. While the same basic argument about the operator not knowing where the tip is, still applies, there is a different reason as to why this is important.

In most cases the object is to pull a relatively thin film of oil from the surface of the water. The ideal place to hold the end of the hose is just above the oil: water level (less than half-an-inch). The air drawn into the gap helps pull the surface layer into the hose, and you don’t pull in a lot of water.

Unless you have really good control of your position (bearing in mind you are looking along the hose at the water) this is very hard to sense. If you push the hose into the water hardly at all then you pull in too much water and not that much oil.

If you tilt the hose then it tends to pull in a lot of air, and not a whole lot of water or oil.

The best way to control the position is to have the end of the hose attached to a piece of foam that will float and in this way the mouth of the nozzle can be placed where you want it. It is easier to do this if you bend the hose so that most of it is lying on the foam, and not pushing it into the water, but in this way, depending on the amount of oil, you can slide the nozzle up and down in the foam to get the best distance to recover the oil.

That half-inch distance is fairly critical for best performance, especially if you can keep just below it. (Yeah we actually did experiments where we adjusted it).

There are now whole books on this technology, and some safety recommendations on how to use some of the equipment, as the industry continues to grow. Hopefully this has been of some help. What one learns in one application can be quite usefully applied, often in others.

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