Rotation and balance of oil effecting Earth's rotation

[Gedanken]

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?

 

[jim mcnamara]

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.

 

[davenn]

Lastly, do you know of any concrete observations that support your claim?

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

shouldn't that affect Earth's rotation on its axis?

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

 

[jim mcnamara]

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

Okay by me. Let's wait and see.

 

[Gedanken]

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.

 

[jim mcnamara]

@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.

 

[RogueOne]

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.

 

[Gedanken]

Thank you Mr. McNamara for the advice. I will probably propose more scenarios in the General Discussion. Why not? Thanks again!

 

[backspace]

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 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-Earth's-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

 

[jim mcnamara]

@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.

 

[backspace]

@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.

 

[rbelli1]

I like that the system is designed with "fuzzy" information

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

 

[jim mcnamara]

@rbelli - In that link, I do not see a discussion of a fuzzy signal, like the weirdness DOD (selective availability) 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?

 

[rbelli1]

I do not see a discussion of a fuzzy signal

Intentional Errors!

As hard as it may be to believe, the same government that spent $12 billion to develop the most accurate navigation system in the world intentionally degraded its accuracy. The policy was called "Selective Availability" or "SA" and the idea behind it was to make sure that no hostile force or terrorist group can use GPS to make accurate weapons.

Basically the DoD introduced some "noise" into the satellite's clock data which, in turn, added noise (or inaccuracy) into position calculations. The DoD may have also been sending slightly erroneous orbital data to the satellites which they transmitted back to receivers on the ground as part of a status message.

Together these factors made SA the biggest single source of inaccuracy in the system. Military receivers used a decryption key to remove the SA errors and so they're much more accurate.

Turning Off Selective Availability

On May 1, 2000 the White House announced a decision to discontinue the intentional degradation of the GPS signals to the public beginning at midnight. Civilian users of GPS are now able to pinpoint locations up to ten times more accurately. As part of the 1996 Presidential Decision Directive goals for GPS, President Clinton committed to discontinuing the use of SA by 2006. The announcement came six years ahead of schedule. The decision to discontinue SA was the latest measure in an on-going effort to make GPS more responsive to civil and commercial users worldwide.

?

BoB

 

[jim mcnamara]

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

 

[davenn]

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

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

In GPS technology, the term "COCOM Limits" also refers to a limit placed on GPS tracking devices that disables tracking when the device calculates that it is moving faster than 1,000 knots (1,900 km/h; 1,200 mph) at an altitude higher than 18,000 m (59,000 ft).[2] This was intended to prevent the use of GPS in intercontinental ballistic missile-like applications.

Some manufacturers apply this limit only when both speed and altitude limits are reached, while other manufacturers disable tracking when either limit is reached. In the latter case, this causes some devices to refuse to operate in very high altitude balloons.[3]

Dave

 

[jim mcnamara]

I knew about COCOM. Thanks.

 

[Baluncore]

When oil is taken from the ground, it leaves a cavity that doesn't get backfilled.

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.