We have been imagining and roughly engineering improved solutions to the "BP Oil Spill" with hopes of creating solutions which can be implemented quickly from existing equipment and materials. See our last posting.
Over the 6 - 8 May period, BP discovered that at the 5,000 foot depth of the leaks (now down to 2 leaks with 1600 feet between the 4,200 Barrels/D and 800 B/D contributors), their inverted box of steel and concrete allowed methane hydrates to form and fill up the box. Methane hydrates form at these ambient temperatures (0 to 5 degrees C.) and about 150 BAR (atmospheres) forming a slush and some larger crystals adhere to the box. Adherence is severe since the interior surface of concrete probably promotes crystal growth. Since the methane hydrates are less dense than seawater, the box is not only plugged up, but will tend to float as hydrates are formed. Whoops.
There is nothing new about methane hydrates: the ocean floor is teeming with them, mostly buried beneath softer surfaces. Anywhere methane and water get together at low temperatures and high pressures, you get the dreaded hydrates. So how can this method be improved to either not allow hydrates to form or to raise temperatures (and lower pressures) and both melt and prevent hydrates?
We recommend raising the altitude of the collection device ... get close to the surface, but well below wave depth. Capture the oil droplets and gas (at that altitude) bubbles where hydrates cannot form. Our "inverted tent" from the previous posting needs to be positioned in the sea at a depth of 100 meters or even less, where the rising plume of oil and gas can be captured in the tent. Rising to the top of our tent, the hydrocarbons will be drawn upward through large holes at the crown of the tent, along with a much larger volume of seawater. On surface work/tank barges, positioned by tugs, the stream will be phase separated into 3 phases. Gases will be flared until compression/collection shipping can be affected. Hydrocarbon liquids will float on the surface of a seawater phase, to be collected and tanked to shore facilities. Seawater, maybe saturated with hydrocarbons and perhaps with some fine hydrocarbon droplets, will be drawn from the lower phase, and pumped at low head for return under the sea to the bottom of the inverted tent.
Thus, we 1) establish a large flow of seawater upward with the hydrocarbon phases and 2) allow contaminated seawater to be re-exposed and re-equilibrated with hydrocarbons. If need be, we can haul off barges of contaminated seawater for treatment. More efficiently, we can install electrostatic/ chemical means of cleaning the seawater before it is recycled. The net result is to cut the pollution, with the goal that anything that floats to the surface in the plume will tend to be captured and used or treated.
The only problems we see in this approach are mechanical, to adapt to the laws of hydraulics and fluid flow. We have chosen ocean-friendly materials. There may be a current, which would tend to drag and distort our tent. The tent must have a large enough open mouth (viewed from the bottom) to capture the width of the hydrocarbon plume at this distance far above the bottom leaks (We don't have but someone knows the width and shape of the plume at 50 to 100 meter depth.) We expect that a rectangular tent or tents of between 120 and 200 feet per side will capture a great deal of the hydrocarbon plume. Reinforced, "rip-proof" nylon which has been coated by PVC seems to us to be an ideal off-the-shelf choice and is available in such sizes (e.g. revival tents or circus tents). Fabric construction allows easy modification and reinforcement.
We know of ways to adapt sea-water-powered cylinders made of coated fabric to holding the shape of the tents under the forces we anticipate. With a tent, these power cylinders can be stitched to the reinforced tent and recoated with coatings to provide a leak proof tent (perfection is not needed). The forces seem capable of handling with this construction.
See the attached artist rendering of one such configuration for our inverted tent collector. We welcome ideas for how to improve on this approach.
The tents, collection piping and supports for such a collector will not be under major wall stress, as the internal seawater and the external seawater have virtually the same hydraulic head. Pressure drops will be designed to be low. With surface tank barges fitted with working decks, the collector can be constrained between barges, which are rigidly attached to each other. This will help the collector maintain its horizontal location over the oil plume as tugs maintain the position of the 2 barges. We would envision flexible connectors between the barges and the riser or descender piping, so that the collector would be stable in the vertical dimension as the wave action caused the barges to rise and fall.
Not that cost of a fix is the top consideration, but this approach is not capital equipment intensive. As we envision this component-based approach being built and stockpiled near all potential leaks, or installed on structures for deployment, low capital cost will become much more important.
Since this BP accident is 50 miles offshore from Louisiana, and the next accident is Zeus-knows-where, we have given thought to transporting this rig from where major fabrication is to occur. We would fabricate the reinforced tents and truck to a nearby boatyard. We would assemble the subsea piping around the tents. All piping would be sealed, all reinforcing cylinders would be sealed, and both would be filled with low pressure (say 1 BAR) nitrogen, making the subsea assembly float. Once in the water (built on inflated rollers, say, and pulled into the water) the assembly would be towed to the site and connected to the other equipment delivered on 2 barges, all away from the plume. Seawater under pressure would displace the transport nitrogen, allowing the rig to sink to desired depth. Flows would be established using seawater only. Then 2 or more tugs would reposition the entire rig with the tent over the plume, where oil and gas would begin to accumulate. Voila!
That will work for Phase I: if we are correct about the horizontal extent of the plume, we can establish 95+% recovery of floating crude hydrocarbons. If the plume is wider, use more tents, since everything else expands linearly. If needed, we can increase the re-circulating flow of crude oil, since this will reduce the forces on our piping and our tent. At some difficulty, the rig could be lower in the water if that worked better.
When BP succeeds in stopping the leak, we can disassemble the parts, float the rig back to shore and await the next time we need to catch a deep bottom leak of oil or gas.
Did you notice that we had no problem with hydrates?
Did you notice that we did not use one of the worlds most sophisticated and expensive drill ships for several months?
Did you also notice that we did not purposely (or porpoisely?) disperse toxins into the ocean?
So there you have it. We wonder how long it will take to hear from someone at BP! Did someone copy Bill Maher on this?
Over the 6 - 8 May period, BP discovered that at the 5,000 foot depth of the leaks (now down to 2 leaks with 1600 feet between the 4,200 Barrels/D and 800 B/D contributors), their inverted box of steel and concrete allowed methane hydrates to form and fill up the box. Methane hydrates form at these ambient temperatures (0 to 5 degrees C.) and about 150 BAR (atmospheres) forming a slush and some larger crystals adhere to the box. Adherence is severe since the interior surface of concrete probably promotes crystal growth. Since the methane hydrates are less dense than seawater, the box is not only plugged up, but will tend to float as hydrates are formed. Whoops.
There is nothing new about methane hydrates: the ocean floor is teeming with them, mostly buried beneath softer surfaces. Anywhere methane and water get together at low temperatures and high pressures, you get the dreaded hydrates. So how can this method be improved to either not allow hydrates to form or to raise temperatures (and lower pressures) and both melt and prevent hydrates?
We recommend raising the altitude of the collection device ... get close to the surface, but well below wave depth. Capture the oil droplets and gas (at that altitude) bubbles where hydrates cannot form. Our "inverted tent" from the previous posting needs to be positioned in the sea at a depth of 100 meters or even less, where the rising plume of oil and gas can be captured in the tent. Rising to the top of our tent, the hydrocarbons will be drawn upward through large holes at the crown of the tent, along with a much larger volume of seawater. On surface work/tank barges, positioned by tugs, the stream will be phase separated into 3 phases. Gases will be flared until compression/collection shipping can be affected. Hydrocarbon liquids will float on the surface of a seawater phase, to be collected and tanked to shore facilities. Seawater, maybe saturated with hydrocarbons and perhaps with some fine hydrocarbon droplets, will be drawn from the lower phase, and pumped at low head for return under the sea to the bottom of the inverted tent.
Thus, we 1) establish a large flow of seawater upward with the hydrocarbon phases and 2) allow contaminated seawater to be re-exposed and re-equilibrated with hydrocarbons. If need be, we can haul off barges of contaminated seawater for treatment. More efficiently, we can install electrostatic/ chemical means of cleaning the seawater before it is recycled. The net result is to cut the pollution, with the goal that anything that floats to the surface in the plume will tend to be captured and used or treated.
The only problems we see in this approach are mechanical, to adapt to the laws of hydraulics and fluid flow. We have chosen ocean-friendly materials. There may be a current, which would tend to drag and distort our tent. The tent must have a large enough open mouth (viewed from the bottom) to capture the width of the hydrocarbon plume at this distance far above the bottom leaks (We don't have but someone knows the width and shape of the plume at 50 to 100 meter depth.) We expect that a rectangular tent or tents of between 120 and 200 feet per side will capture a great deal of the hydrocarbon plume. Reinforced, "rip-proof" nylon which has been coated by PVC seems to us to be an ideal off-the-shelf choice and is available in such sizes (e.g. revival tents or circus tents). Fabric construction allows easy modification and reinforcement.
We know of ways to adapt sea-water-powered cylinders made of coated fabric to holding the shape of the tents under the forces we anticipate. With a tent, these power cylinders can be stitched to the reinforced tent and recoated with coatings to provide a leak proof tent (perfection is not needed). The forces seem capable of handling with this construction.
See the attached artist rendering of one such configuration for our inverted tent collector. We welcome ideas for how to improve on this approach.
The tents, collection piping and supports for such a collector will not be under major wall stress, as the internal seawater and the external seawater have virtually the same hydraulic head. Pressure drops will be designed to be low. With surface tank barges fitted with working decks, the collector can be constrained between barges, which are rigidly attached to each other. This will help the collector maintain its horizontal location over the oil plume as tugs maintain the position of the 2 barges. We would envision flexible connectors between the barges and the riser or descender piping, so that the collector would be stable in the vertical dimension as the wave action caused the barges to rise and fall.
- The fabrication of this rig would be facilitated by using goods and methods readily available on the U.S. Gulf Coast.
- Off-shelf "revival" tents of rip-resistant nylon fabric coated with PVC, reinforced by stitching industrial straps and power cylinders to the inside or outside surface of the te
- We believe that high strength tubing is available, since pressures will be low.
- Piping is low head, either PVC pressure pipe or glass-resin composite piping is widely available.
- Typical ocean-going tank barges for support/receiving/work can be used; cranes, pumps, compressors, and other equipment can be located on a steel deck
- Underwater work can be either robotic or human divers, as appropriate, if depth is small enough.
Not that cost of a fix is the top consideration, but this approach is not capital equipment intensive. As we envision this component-based approach being built and stockpiled near all potential leaks, or installed on structures for deployment, low capital cost will become much more important.
Since this BP accident is 50 miles offshore from Louisiana, and the next accident is Zeus-knows-where, we have given thought to transporting this rig from where major fabrication is to occur. We would fabricate the reinforced tents and truck to a nearby boatyard. We would assemble the subsea piping around the tents. All piping would be sealed, all reinforcing cylinders would be sealed, and both would be filled with low pressure (say 1 BAR) nitrogen, making the subsea assembly float. Once in the water (built on inflated rollers, say, and pulled into the water) the assembly would be towed to the site and connected to the other equipment delivered on 2 barges, all away from the plume. Seawater under pressure would displace the transport nitrogen, allowing the rig to sink to desired depth. Flows would be established using seawater only. Then 2 or more tugs would reposition the entire rig with the tent over the plume, where oil and gas would begin to accumulate. Voila!
That will work for Phase I: if we are correct about the horizontal extent of the plume, we can establish 95+% recovery of floating crude hydrocarbons. If the plume is wider, use more tents, since everything else expands linearly. If needed, we can increase the re-circulating flow of crude oil, since this will reduce the forces on our piping and our tent. At some difficulty, the rig could be lower in the water if that worked better.
When BP succeeds in stopping the leak, we can disassemble the parts, float the rig back to shore and await the next time we need to catch a deep bottom leak of oil or gas.
Did you notice that we had no problem with hydrates?
Did you notice that we did not use one of the worlds most sophisticated and expensive drill ships for several months?
Did you also notice that we did not purposely (or porpoisely?) disperse toxins into the ocean?
So there you have it. We wonder how long it will take to hear from someone at BP! Did someone copy Bill Maher on this?
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