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Rotation and balance of oil effecting Earth's rotation

  1. Apr 29, 2017 #1
    When oil is taken from the ground, it leaves a cavity that doesn't get backfilled. If material were taken from anywhere on a billiard cue ball, it would throw it out of balance. Trillions of gallons of oil have been displaced over roughly 100 years, shouldn't that affect Earth's rotation on its axis?
     
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  3. Apr 29, 2017 #2

    jim mcnamara

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    We do not do personal theories. PS: please do not do this because it normally results in thread closure.

    First off, Earth's crust is not of consistent density - you can walk around and find small anomalies in the acceleration of gravity due to less/more dense material way underground. So, Earth does not compare well to a billiard ball. At all.

    Next, compared to the mass of the earth, the amount of oil is trivial. Detecting anything would be really, really hard - see below.

    Next, consider the fact that tectonic plates exist of vastly greater mass than the oil. Continental areas on the plates do have more mass than ocean bed - sometimes piled up into large mountains. And changes to them have very tiny effects on the earth's period of rotation. For that matter, huge subduction quakes also impact period of rotation. Plus the Earth is a pain in the butt astronomically because the duration of every day varies from every other day by a millisecond or so.
    See what that sneaky ball of a home, Earth, did to today - you can lookup earlier data if you want.:
    https://www.timeanddate.com/time/earth-rotation.html
    The point of this: the change from day to day is normal, so spotting the incredibly tiny effect you stipulate is more than hard, it is very close to impossible, IMO.

    Lastly, do you know of any concrete observations that support your claim? I can provide textbook geology citations for all of those things I mentioned.
     
    Last edited: Apr 29, 2017
  4. Apr 29, 2017 #3

    davenn

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    I don't really think he/she is making a claim/personal theory

    maybe wouldn't instead of shouldn't may have been a little better
    I still just see it as asking a simple question to which you have given a clear answer that should satisfy him/her

    that is, that compared to the mass of the earth, the mass of oil removed is tiny

    Dave
     
  5. Apr 29, 2017 #4

    jim mcnamara

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    Okay by me. Lets wait and see.
     
  6. Apr 30, 2017 #5
    First of all, I apologize for not reading the "agreement" before posting my question. As a former oilfield worker I have thought about this for years and couldn't find a good answer. I found Physics Forums and thought this would be a good place to submit my question, which has finally been answered logically and objectively. Thank you for not booting the thread! And I won't ask anymore uneducated questions! Thanks.
     
  7. Apr 30, 2017 #6

    jim mcnamara

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    @Gedanken You can ask 'sort of" questions in general discussion. Say something like "I need help understanding this idea: blah blah" You will get an answer like the one I gave. And nobody will have a problem with the question. The reason for the rule is that people tend to think up something in the shower and then can't find it on google - cause it does not exist - then ask here in these forums. "Because."

    We get about 2-3 questions every day very like what you asked. It is impossible to see intention or forethought in a post, especially from cell phone app users and their terse approach.
     
  8. May 2, 2017 #7
    Yes it will affect earth's rotation about its axis. That is basic physics. However, the effect is negligible. This is even more so when you consider the fact that oil is drawn world wide. So there is some counteracting happening.

    I look at this the same as I look at a person's effect on earth's orbit when they jump up and down. Equal and opposite reaction has to happen, obviously. However, it is minute.
     
  9. May 2, 2017 #8
    Thank you Mr. McNamara for the advice. I will probably propose more scenarios in the General Discussion. Why not? Thanks again!
     
  10. May 7, 2017 #9
    Rule break!!
    Gedanken,

    Well, I hope this is kept in this discussion and that you are still watching it!

    The answer to your 'improper forum' question is yes.

    "Raising 39 trillion kilograms of water 175 meters above sea level will increase the Earth’s moment of inertia and thus slow its rotation. However, the effect would extremely small. http://www.jpl.nasa.gov/news/news-print.cfm?release=2005-009 [Broken]calculated that shift of such as mass would increase the length of day by only 0.06 microseconds and make the Earth only very slightly more round in the middle and flat on the top. It would shift the pole position by about two centimeters (0.8 inch). Note that a shift in any object’s mass on the Earth relative to its axis of rotation will change its moment of inertia, although most shifts are too small to be measured (but they can be calculated)."
    http://www.businessinsider.com/chinas-three-gorges-dam-really-will-slow-the-earths-rotation-2010-6

    also:
    http://www.physics-astronomy.com/2014/05/how-infamous-hydroelectric-dam-changed.html#.WQ9MsYWcHIV

    So sucking oil out of the ground does have the same effect but due to location, the numbers would be different from the Chinese dam figures obviously.
    -regards to all
     
    Last edited by a moderator: May 8, 2017
  11. May 7, 2017 #10

    jim mcnamara

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    @backspace - are you aware of the variation in rotational period of the earth from day to day? The numbers are correct, but measuring the actual (not calculated) effect is difficult. See ephemeris software ftp://ssd.jpl.nasa.gov/pub/eph/planets/other_readers.txt This is also a big deal for GPS, as corrections to their ephemerides are needed.

    Here is a discussion of ephemeris errors and their effects by Trimble http://www.trimble.com/gps_tutorial/howgps-error2.aspx
    @davenn can provide good information on this, I believe.

    Good post BTW. Thanks.
     
  12. May 7, 2017 #11
    @jim mcnamara

    Thanks,
    Interesting about the variations and the difficulty in calculating them.
    the trimble tutorial is good. I like that the system is designed with "fuzzy" information and needs a special code to find the real point.
     
  13. May 8, 2017 #12

    rbelli1

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    They shut off the fuzzy 17 years ago. New GPS satellites aren't even being equipped with the fuzz generators.

    While fuzzy sounds good why do you like degraded signals?

    BoB
     
  14. May 8, 2017 #13

    jim mcnamara

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    @rbelli - In that link, I do not see a discussion of a fuzzy signal, like the weirdness DOD (selective availablility) mandated up until about the end of 1999.
    I think. At least I am trying to direct attention to variations in Earth's rotational period. We are discussing the fact that all kinds of factors mess up the accuracy of GPS, one of them relates to the required hourly updates of ephemerides due to earth slowing down & speeding up and other physical effects, like WAAS information.

    I thought the Trimble article was okay. Just the right level. MAybe not?
     
  15. May 8, 2017 #14

    rbelli1

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    ???

    BoB
     
  16. May 8, 2017 #15

    jim mcnamara

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    Yes. I do not see that SA is active. And you are right it is mentioned. I originally thought you meant the article implied SA was still up. My bad. @rbelli1
     
  17. May 9, 2017 #16

    davenn

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    whilst we are still a little off the original topic....
    as far as I am aware, this is the only limitations imposed on today's GPS operations
    from Wiki .... and I have seen this written in the Trimble GPS articles at work for various receivers


    Dave
     
  18. May 9, 2017 #17

    jim mcnamara

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    I knew about COCOM. Thanks.
     
  19. May 17, 2017 #18

    Baluncore

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    I would expect the reservoir to be backfilled with water to assist in the removal of the oil. If not, ground water would be expected to flow into the area from which hydrocarbons were removed. Since the density of water is greater than the oil or gas, the mass of the reservoir may actually increase.

    Where the surface sags due to the removal of hydrocarbons, much of the product will be burnt as fuel. It will make atmospheric CO2 and atmospheric water, which quickly becomes surface water that can go back down a hole. So the mass distribution does not change by as much as you might at first have expected.
     
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