Hydrofracking question.

Discussion in 'Earth Science' started by bunnyversusworld, Feb 29, 2012.

  1. bunnyversusworld Registered Member

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    I know there's much opposition to hydrofracking but I read a post by an engineer claiming that hydrofracking happens far below the water table. But surely when they pump the gas back up the well it and the contaminants must pass through the water table again. Can someone explain this technology to me?
     
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  3. adoucette Caca Occurs Valued Senior Member

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    When they pump the gas back up the well, it will be inside a pipe.

    That's what they do when they drill an oil or gas well, they put a PIPE down the hole they drill.
     
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  5. arauca Banned Banned

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    As they blow up below the water table . Cracks will develop in the water table because of the organic pressure below it will diffuse into the water table and contaminate it specially if the water table is sand . Than as the well owner pumps water he will pump a mixture or oil with water .
     
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  7. billvon Valued Senior Member

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    Hydrofracking is intended to "blow open" pores in rock to allow gas to flow more easily, and also contains "proppants" like sand to keep the pores open. This makes the rock near the well more permeable - and thus allows both fracking fluids and methane to flow beyond the well itself. This has resulted in several cases of contamination of drinking water supplies and even one case where a well exploded due to high concentrations of methane.

    In addition, leaks and well explosions can result in the release of fracking fluids directly into local streams and lakes.
     
  8. adoucette Caca Occurs Valued Senior Member

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    Yes, but that's not typical.

    Typically gas wells are many thousands of feet below any groundwater supply, with many layers of impermeable rock between them.

    Indeed, if the rock layers above the gas were permeable, the gas wouldn't be there.

    http://www.energyfromshale.org/ground-water-protection
     
  9. billvon Valued Senior Member

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    12,806
    Agreed. But keep in mind that the purpose of hydrofracking is to make impermeable layers of rock permeable. Done correctly fracking increases permeability only in areas that contain gas and does not affect nearby water tables - but in many cases the effects have extended beyond what geologists predicted.
     
  10. adoucette Caca Occurs Valued Senior Member

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    Yes, but many THOUSANDS of feet below any water table.

    Gas just isn't usually found nearly that close to the surface.

    Most of the issues I've read about have been with surface disposal of the drilling fluids, not the actual wells.
     
  11. Trippy ALEA IACTA EST Staff Member

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    Incidents where hydraulic fracturing is a suspected cause of drinking water contamination

    State Report


    Addendum:
    Osborn, Stephen G.; Vengosh, Avner; Warner, Nathaniel R.; Jackson, Robert B. (2011-05-09). Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing. Proceedings of the National Academy of Sciences.
     
    Last edited: Feb 29, 2012
  12. adoucette Caca Occurs Valued Senior Member

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    And that had nothing to do with the process of Hydraulic Fracturing.

    Which is the problem.

    Just because a well that is using Hydraulic Fracturing causes a problem doesn't mean it is related to the Hydraulic Fracturing process itself.

    As the report states:

    Over 79,000 wells have been drilled to the “Clinton sandstone” in eastern Ohio.

    So yeah, occasionally there will be problems.

    Getting energy out of the earth, via well or mine is not totally without any risk.
     
  13. Trippy ALEA IACTA EST Staff Member

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    And yet it had everything to do with hydrofracking at gas wells.

    Also note in the portion you quoted.
    "This over-pressurized condition resulted in the invasion, or migration, of natural gas from the annulus of the well into natural fractures in the bedrock below the base of the cemented surface casing."

    In other words, a problem at the surface, caused over pressurization, that resulted in back pressure forcing the gas through the fracked region, and [then] through the natural fractures in the rocks to the water table.

    The contamination didn't occur at the surface, it occured through the bedrock.

    Any comments on any of the other incidents listed on that website? Or for that matter the PNAS article regarding the widespread contamination of groundwater above fracked shales in New York and Pennsylvania?
     
  14. bunnyversusworld Registered Member

    Messages:
    28
    So, what percent of hydrofracked wells cause contamination in the water table? How far does this contamination spread from the source? How long does it remain at toxic levels in the water table? How great is the area of a water table? Are they interconnected tables? Are there any substitutes for these proppants? What percent of natural gas wells are hydrofracked? thanks
     
  15. billvon Valued Senior Member

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    12,806
    Agreed. Looks like they have some work to do with hydrofracking to make it safe enough, though.
     
  16. adoucette Caca Occurs Valued Senior Member

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    Nope.

    BELOW THE BASE OF THE CEMENTED SURFACE CASING.

    Here's a diagram

    http://www.energyfromshale.org/sites/default/files/Shielding-Ensures-Safety.pdf

    The leak was just below the Surface casing, near the TOP of the well.

    (The Surface casing would be the one that extends just below the Aquifer)

    The Fracking is going on at the very BOTTOM of the well.
     
    Last edited: Mar 3, 2012
  17. adoucette Caca Occurs Valued Senior Member

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    Lisa Jackson on Fracking:

    “I’m not aware of any proven case where the fracking process itself has affected water, although there are investigations ongoing,” she said.
     
  18. arauca Banned Banned

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    From Poland with love
    Email


    WARSAW, Poland (AP) — A scientific study in Poland has found that shale gas extraction at one site produced some toxic refuse but that the waste was reused and didn't harm the environment.

    The report was presented Friday by the Polish Geological Institute, which carried out its study last year when a company, Canadian Lane Energy, began test drilling near Lebien, in northern Poland.

    Poland has some deposits of shale gas and is hoping to exploit them to cut its dependence on Russian natural gas. It hopes to repeat what has happened in the United States, where large shale gas discoveries in the past 10 years have given the country independence in the gas sector.

    It is still unclear, however, how much shale gas there is in Poland, and the process of extracting it has come under fire by environmentalists.

    In hydraulic fracturing, or fracking, a technology developed in the United States, large quantities of pressurized water and some chemicals are used to break underground rocks and release gas trapped in them. Most of the water remains underground, but some returns to the surface and is toxic.

    "Cases of leakage and water contamination in the U.S. show that this is not a safe technology," Katarzyna Guzek of Greenpeace told The Associated Press.

    The report said the procedure at the site it studied produced some highly toxic liquid and some solid refuse, but that it was all either reused or utilized. Laboratory studies found no pollution to surface or ground water, soil or air, it said.

    "Soil, air, water — the studies show that all these elements of the environment are safe if exploration of shale gas is conducted in accordance with legal regulations," the study said.

    Guzek said the study was carried out at the start of exploration in Poland and does not reflect dangers from a long-term activity.

    Lane Energy is among more than a dozen international companies that have obtained licenses to explore for shale gas in northern and eastern Poland.
     
  19. Trippy ALEA IACTA EST Staff Member

    Messages:
    10,890
    Nope.

    Re-examine what I said.

    Now, take another look at the report I linked to - specifically the part where it states that the well casing went down to the bedrock (and indeed, some depth into it, as the bedrock contained a sandstone aquifer [Berea Sanstone] that is used for drinking water).

    Therefore this statement: "The contamination didn't occur at the surface, it occured through the bedrock." is completely accurate, and the only part of this statement: "In other words, a problem at the surface, caused over pressurization, that resulted in back pressure forcing the gas through the fracked region, and [then] through the natural fractures in the rocks to the water table." That I have yet to demonstrate is that the fractured region had anything to do with it in the way I have suggested.

    We also have this:
    "The industry standard for cementing production casing calls for sufficient cement to fill the annulus between the well bore and the casing 600-800 feet above the “Clinton”."
    So the production annulus (one part of the surface-production annulus) was supposed to extend down to within 600-800 feet of the Clinton sandstone.

    We also have this:
    "When a well is properly constructed, the hydraulic fracture is confined between the permitted reservoir formation and the production casing. The abnormal circulation that was observed during the stimulation of the English No.1 well indicates that the frac communicated directly with the well bore and was not confined within the “Clinton” reservoir. This communication could also have provided a conduit for “Clinton” gas to enter the annulus of the well."
    The well was improperly constructed.
    Because the well was improperly constructed, it was improperly fracked.
    Because it was improperly constructed, and improperly fracked, parts of the well bore that would ordinarily not have been fracked, were fracked.

    Because part of the well bore was fracked, that was not supposed to have been fracked, gas built up in the annulus that was not supposed to be in the annulus, and the pressure in the annulus reached levels it was not supposed to. These pressures allowed allowed the gas to infiltrate the natural prosoity of the remaining bedrock, resulting in the groundwater contamination.

    So in any meaningful way, it was caused by the fracking.

    Improper well construction resulted in improper fracking.
    Improper fracking resulted in excess gas buildup.
    Excess gas buildup, compounded by human error, resulted in groundwater contamination through the natural porosity of the rock.

    Note that the formation that was improperly fracked, that resulted into the gas leaking into the well - the fracking that the bore casing was in direct communication with, was into Newburg Dolomite, as evidenced by the fact that in all cases of contamination, its distinctive smell was noted. Note that Newburg Dolomite is a member of the Lockport group.

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  20. Captain Kremmen All aboard, me Hearties! Valued Senior Member

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    The Oil industry doesn't want to undermine its investment in oil at the moment.
    When it wants to turn to fracking, we will have our fuel supply from fracking.
    It is not necessarily polluting, any more than oil exploration.
    If the fines for pollution are set high enough, the level of pollution will be limited.
    You can be damn sure there will be no pollution in the Gulf of Mexico again.
    As usual, poor countries will suffer far higher levels of pollution than rich ones.
     
    Last edited: Mar 3, 2012
  21. adoucette Caca Occurs Valued Senior Member

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    7,829
    I have looked at it.
    And the Fracking wasn't done wrong, the problem was in the well that was improperly cemented, and the "communication" would have happened regardless if the gas was from a normal zone or a fracked zone.

    As you diagram says, you can't frack upward to the groundwater layers.

    Which is why, 3 years AFTER that report was issued the head of the EPA said: I’m not aware of any proven case where the fracking process itself has affected water
     
  22. Trippy ALEA IACTA EST Staff Member

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    10,890
    No it wouldn't, because once they get the casing in place in the bore, they perforate the casing in a controled fashion, so that only the target zone gets fracked.

    The problem was a lower layer was naturaly fractured and ended up theiving the concrete, they new this, and went ahead with the fracking regardless, and consequently ended up fracking the wrong layer. Therefore the well was by any reasonable definition improperly fracked.

    This is only true if the well is fracked properly, or the fracking is carried out appropriately. If either, or both of these should be false, it is physically impossible to prevent it from happening.
     
  23. adoucette Caca Occurs Valued Senior Member

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    7,829
    If you were right then Lisa Jackson is a liar.

    Don't think she's a liar.

    And the report doesn't agree with you either and the only issue with the Fracking is it was done when there was minimal Cement behind the production casing.

    Indeed, the Corrective action was simply a new Cement job:


    1. Inadequate primary cementing of the production casing has been remedied by the
    subsequent squeeze cementing operations;
    2. The deep high-pressure gas zones that were the source of over-pressurization of the
    aquifers have been isolated and sealed from the well bore through the squeeze cementing
    procedures;
    3. The confinement of annular gas, which caused the build up of pressure, has been
    eliminated.
     

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