Monday, May 31, 2010

Stopping the BP Oil Spill

Being from Texas, I have been distraught watching the environmental disaster that the Deepwater Horizon Oil Spill has become.  Being also an engineer, I can't help but start brainstorming ideas for how to fix the problem.  Below is a copy of a proposal I have submitted to the Mineral Management Website for technical proposals - it will be interesting to see if I get any response and if so what it is.  I highly encourage others that have ideas regarding stopping the spill or ways to manage the clean up to submit proposals.
While British Petroleum has tried several methods to mitigate or stop the flow of oil from the submerged vestiges of the sunken Deepwater Horizon offshore drilling platform, to date none have been successful.  It is believed highly likely that the relief wells being drilled now will permanently terminate the flow, but it is expected that this operation will not be complete for at least 4 more weeks during which time the size of the spill will double or more.  Below I roughly sketch out a stop-gap measure for significantly reducing the flow of oil form the well head by super-cooling the riser pipe using readily available and inexpensive liquid nitrogen.  British Petroleum most likely already has much of the infrastructure required to do such an operation and assuming the deep-water operations are successful the probability of a significant reduction in flow is high.
Brief Background




Crude oil and two-phase crude oil/gas mixtures have a very strong viscosity dependency on temperature.  At lower temperatures (especially below 0˚F) the viscosity of crude oil and its mixtures increase very rapidly.  As can be seen in the figure I generated below and to the left, the mass flowrate of a fluid through a pipe at constant pressure drop is a very strong function of the viscosity of the fluid flowing in the pipe.  Next to it is a plot of viscosity vs. temperature for a two-phase mixture of light crude and natural gas (as the flow coming out of the Deepwater Horizon wellhead is) at a bunch of different pressures.
Figure on left shows mass flowrate dependency on viscosity of fluid.  Figure on right shows the strong dependence of viscosity in oil/gas mixture on temperature (Right figure credit: Lyons, William C., and Joseph Zaba. Standard Handbook of Petroleum & Natural Gas Engineering. Houston, Tex.: Gulf Pub., 1996. Print.)


If one can control the temperature, and thus the viscosity, of the flow of crude from a well the flowrate can be reduced dramatically.
The Proposal

Using common and relatively low cost industrial materials, components and techniques, a cooling jacket can be applied around the broken riser in order to significantly lower the temperature of the oil flowing from the well.  This will increase its viscosity and lower the flowrate in an accelerating feedback loop:
Several companies make clamp-on liquid nitrogen collars for freezing fluids in pipes.  They are off the shelf cryogenic components:
Cryo-lator pipe freezing collar (courtesy www.cryolator.com)


An alternate method would involve pumping liquid nitrogen directly into the well head below the break in the hope of forming hydrate and extremely thick crude “sludge” that would plug up the riser, slowing or haulting flow:
This method would likely also be worth considering although it would require somehow breaching the riser pipe and installing a leak-tight connection to a very high pressure liquid nitrogen line which could be problematic at these depths.
Required Equipment
  1. Large, clamp-on liquid nitrogen circulator for the riser pipe.  This would probably be a custom component manufactured for the size pipe being used at the sea floor.
  2. Long stainless steel or cryogenic-quality aluminum pipes to transport liquid nitrogen from the surface to the sea floor.  Stainless steel or aluminum are required for cryogenic liquids as they don’t become brittle at low temperatures.  It is likely that much of the plumbing BP already uses is stainless steel so they probably have this available.
  3. Large cryogenic holding vessels for liquid nitrogen.  These are readily available from gas suppliers such as AirGas and could be plumbed together in a large array on a barge.  Alternatively, a cryogenic transport ship for liquid natural gas (LNG) could be filled with liquid nitrogen instead, storing huge amount.
  4. Large cryogenic pumps.  These are commonly used in industry for moving large quantities of liquid nitrogen and liquid oxygen.  They are also very commonly used in the petroleum industry so chances are that BP has ships with these already installed.
  5. Capable deep water ROV’s to install the collar and associated plumbing on the riser.  BP has already been using such devices to try their other fixes.  They should be capable of this operation.
Potential Problems

  1. The single largest reason why this proposal may not work is the two-phase nature of the flow coming out of the well.  Gas mixed with liquid behaves very different than pure liquids and some analysis would need to be done to show that cooling this mixture would reduce flowrate significantly.  It is likely that it would - the plot shown above for temperature vs. viscosity is for a methane/crude mixture with specific gravity .7 and it can be clearly seen that the viscosity is still greatly affected by temperature.
  2. Getting liquid nitrogen to the ocean floor a mile beneath ships requires a well insulated pipe.  Fortunately, this will happen naturally as ice forms on the pipe once liquid nitrogen begins flowing.  Initially only gas will reach the ocean floor as liquid nitrogen boils in the pipes, cooling them down.  This is actually beneficial as well since it will dry out the entire nitrogen circuit making internal ice build-up unlikely.  As the pipes cool and ice forms insulating their outer walls, the liquid nitrogen will stay in a liquid state to deeper and deeper depths until it reaches the sea floor.  Getting to this point will take time and significant amount of liquid nitrogen, but it is an extremely cheap substance as it is made of air.
  3. The ice buildup on the pipes could provide structural problems for them.  Ice is less dense than water so it would provide a buoyant force trying to pull the pipes upward.  Analysis would have to be done to show that the pipes are strong enough to withstand this.
    Conclusion
    While there are some potential pitfalls with this proposal, it seems to have enough merit to at least warrant further analysis by those in charge at BP and the federal government.  It is my hope that by writing this white-paper, someone will take notice and at least consider this as an option.



    48 comments:

    vaporland said...

    why aren't they using a form of inflatable plug?

    http://webstore.petersenresources.com/inflatable_plugs.aspx

    vaporland said...

    Petersen Inflatable Pipe Plugs, Grout Bags, and Packers are ideal for hot tapping, under water installation, insertion through confined areas, testing pipelines, and many other requirements.

    DJ said...

    Nice idea! Much luck to your effort to get it heard! Being on Hack-a-Day will help.

    TropicalSpeed@comcast.net said...

    There is no reason that both procedures couldn't be used. The BOP is still in place and it has connections for injection. BP is currently using one or more to inject an anti-freeze.

    I have seen the videos from the seabed and the riser has just been cut from the BOP stack. The only thing that now resides on top of the BOP is a flange. Why can't they remove the flange, install an open gate-valve in its place, and then turn the valve off? Probably for the same reason that they haven't tried nitrogen - either they are know something that we don't or they are just too stupid to think of trying it.

    JOHN said...

    What no one seems to realize is that BP's work on the well isn't about stopping the leak and never was. There work has ALWAYS been about repairing the leak so they can continue to recover oil from the site. Stopping the leak could have been successfully achieved within the 1st week.
    Now if the poor people of Louisiana and Florida would simple start using Microbes on the oil in the water/beaches then all the money wasted on extra manpower would be saved and the cleanup would go alot faster. Texas has successfully used them on oil cleanup in the past but for some reason they're not being used. http://www.youtube.com/watch?v=8VfypUzx1tI

    dlciii said...

    No the idea is not to recover the well. The relief well is the only way to fix this. Methane gas is crystallizing under the pressure and temperature of this environment. Liquid nitrogen will not have the effect you intend. But there are other options. None really feasible to your idea of putting a snow ball in the end of a jet producing as much fluid at such a high pressure as this leak is right now. The relief well will be the only way to fix this issue. It just takes time. I do commend your efforts. This is just not the way.

    jim said...

    The conspiracy talk
    is a distraction, and
    criminal charges are for later,
    as long as evidence is preserved.
    But thinking outside the box is good,
    and though petroleum engineers often do so,
    good efforts with foundation are good.
    Even I felt compelled to file a suggestion.

    The bottom of the BOP is at 7,000 psi, and the
    riser piping at the top of the BOP won't take that.
    So only a dynamic seal would keep the exit pressure
    low enough while holding high pressure lower in
    the BOP for the injection of concrete for well seal.
    If the mud flow stalls, the pressure spikes beyond
    the riser strength.
    But stopping the oil now is more urgent than
    sealing the well, so cooling could be helpful.

    Expansive freezing of seawater is to be avoided,
    as well as unwanted forming of methane hydrates
    that might stall flow and fracture the riser piping.

    Freezing steel reduces its strength, and sometimes
    uncertainties must be considered as prohibitive,
    since things actually could get worse.

    Using nitrogen phase change has potential to
    slow the oil flow as an assist for riser work, but
    it might better be done from tanks near the BOP.
    Chemical reactions, thermodynamics, and
    stresses can be messy down there.

    There should be sites, like this blog, where
    preliminary ideas are discussed, modified,
    and vetted; then passed to a higher level for
    another round of vetting; then to MMS.

    jonnyd said...

    Thanks for the comments guys. The purpose of this proposal would not be to stop the leak -only to slow it until the relief wells are drilled. I agree with the last post that thermodynamics are tricky at 7000 psi and below freezing temperatures, but liquid nitrogen is so cold, there is no doubt that it would significantly raise the viscosity of oil if it could be introduced to it effectively. I don't claim this is the only solution or even that it would work, but as the last poster says, it would be nice if there were places for open technical discussions about possible solutions. More ideas are always better and there are many many smart people in the world, most of which do not work for BP.

    TropicalSpeed@comcast.net said...

    Here is a simple containment idea. But, now that it has been brought to light that the wellhead pressure could be as much as 7,000psi, this may not be a viable solution after all. But, here it is anyway:
    What if a large dome were fabricated and then lowered onto the seabed over the wellhead. Then, cement is pumped into the dome to displace the water and seal the well.

    Laura said...

    I like your idea. I wonder if instead of a collar or injection into the side of the pipe, if the N2 pipe could be shoved into the oil pipe.

    Scott said...

    Ignoring the wellhead pressure, the water column pressure down there is >2000 PSI, at which point even at 32F, you're above nitrogen's triple point. It's not going to boil, so heat transfer will be pretty minimal. If you try to keep the jacket pressure below nitrogen's supercritical pressure, your jacket will have to withstand 1500PSI, because nitrogen's supercritical pressure at 32F is only 500PSI.

    Venting LN into the wellhead wouldn't cause the effect you're looking for because the LN wouldn't boil.

    Heat transfer wouldn't be that great in a jacket, either, because of wall superheat.

    dlciii said...

    Ok, so this idea won't work. BUT, I think the idea that is important here is a forum for presenting and debating random ideas and solutions to the teeming masses. I know there are a bunch available. But I love this public question answer thing that happened with this idea. I need more. Again three cheers for putting your neck out and tossing your hat in the ring.

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    TropicalSpeed said...

    ames Cameron was on CNN yesterday and explained to the viewers that a simple shut-off or a plug at the top of the well is not possible because of the extreme pressures. His group estimated the pressures at the bottom of the well to be 12,000psi. Cameron went on to say that the top of the well can be throttled with a valve but as the valve is closed further, the pressures will build up in the the casing causing leaks elsewhere. If that be the case then, how can a BOP which is nothing more than a valve at the top of the well, be used to shut down the flow? There seems to be a conflict here regarding this. Anyone care to shed some light on this?

    jonnyd said...

    Scott,

    You're correct that nitrogen is supercritical at these pressures but that doesn't necessarily mean heat transfer is very low. Yes, boiling helps (or can hurt if you get into film boiling regime) but many heat exchangers don't rely on boiling and often actively avoid it. Pumping liquid (or supercritical) nitrogen into the spout may not work, but I disagree that it would not be effective at cooling the flow - mixing two fluids at drastically different temperatures will cause both fluids to change temperature.

    Anyway, I agree there are problems with the idea - I never said it was a silver bullet. I was more interested in starting discussion by proposing it.

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    scott took the words from my mind

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    mnemosynthe said...

    they are looking for submissions for ideas. you could try a submission with them rather than just waiting. :)

    http://www.deepwaterhorizonresponse.com/go/doc/2931/546759/

    ze said...

    Thanks Scott for this great post. Great to see ideas being exchanged and the Internet being used for an important cause -- science.

    I have started a website to help share and discuss the idea of using ice or freezing to slow and eventually stop the flow of oil. I recognize that overcoming the extreme pressure that deep in the ocean will be a challenge and that there are risks with this proposal, but I passionately believe this idea is worth vetting.

    Please check out my website freezeoil.com and participate in the conversation.

    Please contact email me at zach at freezeoil dot com if you are interested in helping with this project and vetting the idea.


    I too have grown tired of not being able to find adequate technical details of the subsea oil leak. All of BP and the fed agents have for fact sheets are how to file claims and for surface recovery. Similarly, it is equally challenging to find any relevant leaks in google (ie. pressure, freeze, temperature) without being overwhelmed by news and emotion about the spill.

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    Liam Scully said...

    Here is a forum on bp website for suggestions, whether they take good ideas seriously is another thing but keep up the good work and lets help clear up this mess.
    Liam

    http://bpoilnews.com/gulf-oil-spill-response/more-gulf-oil-spill-suggestions-from-our-readers/

    jim said...

    The main problem seems to be that the
    casing has been damaged deep down,
    and the back pressure cannot be increased
    to avoid blowouts in the seabed.

    Then there is the flammable methane hydrate
    problem, where highly-compressed methane
    gas is trapped inside structures of water ice.
    And also the problem of 8,000 psi or so into
    the BOP/casing string.

    I saw a video that indicated heavy shocks on the
    seabed; maybe in early June. I wonder if methane
    or crude-oil fraction vapors had some explosive
    events.

    My impression is that the 8-inch drill string is still
    inside both BOP and much of the well, which
    interferes with some options.

    If the casing is badly damaged at a very deep
    level, then using mud to set a cement plug through
    a relief well could be trouble.
    It might become an explosives issue;
    conventional explosives if possible; nuke if must.

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