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A challenge!

  1. Mar 25, 2006 #1
    Hi experts!

    As you will see I am NOT one but I have a rather unique problem in search of a solution.

    I have a natural gas well that runs 11psi but has little volume because it is only 412 feet deep. Rather than pay thousands to drill to approx 850 feet to improve volume, I thought it might be possible to store additional natural gas from the well in a propane tank.

    Current flow from the well provides enough gas to run the hot water tank and gas range only all year. I had the well bailed of water last summer. But, when I turned on the boiler this winter, the flow depleted the well in just one heating cycle. The boiler runs at 145-degrees farenheit. The thermostat is set at 68-degrees all winter. We are back to running the boiler off the gas company supply. Our annual gas company bill averages $1,200.00 with the latest (2005/2006) hikes.

    We are in the Northeast. We use an average 1,000 cubic feet of gas company gas in a 12-month period at 4oz gas company line pressure. The gas company supply is shut off June/July/August/September.

    If a tank is possible, how large a tank would be necessary to store enough gas well gas to be virtually free of the gas company supply?

    Any help will be appreciated.

    jimoferie
     
  2. jcsd
  3. Mar 25, 2006 #2

    Astronuc

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    Well if one uses about 1000 cuft of natural gas (mostly methane) from the gas company, then to be virutally free, one needs about 1000 cuft of gas from the well. The size of the tank would depend on demand, but the maximum size would be 1000 cu ft or ~7500 gallons for storage at atmospheric pressure. As you indicated the gas is supplied from the gas company at 4 oz or 1/4 psig (or about 14.95 psia). Integrating the production rate - consumption rate over a year should give some idea of the storage volume required. Find the point of maximum surplus and that is the size of the tank.

    Bear in mind natural gas is mostly methane, as opposed to propane or butane.
     
  4. Mar 25, 2006 #3
    I really am a "dummy" when it comes to Physics & Math. How does one (figure) integrate the "production rate - consumption rate" over a year?
    I chose a propane tank because they can be found rather inexpensively in our area, even though the psi from the well has never been above 11psi in the 10 years we have been using it. Refurbished tanks can be had between $500 & $750. To re-drill the well to 850 feet would be nearly $6,000.00.

    A well driller said I could try a compressor and drying tank to suck more gas out of the well at a cost of $800.00 for the setup but there is no guarantee that the well won't fill again with water. Bailing the well costs $800.00 alone.

    I certainly have a dilemma!

    jimoferie
     
  5. Mar 26, 2006 #4

    Q_Goest

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    If you use 1000 cubic feet of gas in a year, that is the volume the gas will fill at atmospheric pressure and temperature.

    So in one day, you will use roughly 2.7 cubic feet of gas. To store that amount of gas (enough for a day) and still have roughly 1/4 psig when starting at 11 psig, you need aproximately 3.7 cubic feet of volume or about a 28 gallon tank.

    Get a 50 gallon tank and allow it to fill to 11 psig and you should be good as long as you are regulating the pressure down to 1/4 psig to feed to your appliances.
     
  6. Mar 27, 2006 #5
    Thanks for staying with this problem. I really appreciate it. I apologize for not having all the information to make a sound decision. The Gas Company bill shows CCF as "One hundred cubic feet of gas; a measure of quantity".

    Let me give you our latest gas bill info and a historical perspective.

    In the last 33 days (approx 16 days in February and 17 days in March) we used 174 cubic feet of gas company gas at a cost of $286.00 for a 1,000 sq. ft. well-insulated ranch. That's an average of 5.27 ccf per day. We live by Lake Erie. It has been colder than normal.

    Here is a breakdown of the last 12 months:
    2005: Jan/Feb 28 days:176 ccf . Feb/March 30 days:177 ccf . March/April 28 days: 114 ccf . April/May 35 days:72 ccf . Gas Off: May/June . June/July . July/Aug . Aug/Sept . Sept/Oct 27 days: 17 ccf
    Oct/Nov 29 days: 61 ccf . Nov/Dec 31 days: 144 ccf . Dec'05/Jan'06 34 days: 153 ccf . Jan/Feb 27 days: 129 ccf . For all of 2005 we used 996 ccf, for all of 2004 (a warm Winter) we used 864 ccf.

    Problem: The well will drop to nearly zero from 5psia on the well guage when running the boiler off the well for just one cycle to bring the boiler temp to 145 degrees. The wall thermostat stays at 68 degrees. The boiler eats the gas pretty fast. Now, when it gets down to zero, I shut off the well to allow it to build back up. It took 21 days to build back up to 8-1/2 psia on the well guage. I switched the well back on today to handle the water tank and gas range again.

    I have so many questions: Because it takes 21 days to recover just 8-1/2 psia maybe I need a much much bigger tank? Do I need a tank that can store much more than 177 cubic feet if the boiler burn rate is 5.27 ccf per 24 hours of boiler operation?

    Maybe this is just not economically practical?

    Thanks again for looking at this.
    jimoferie
     
  7. Mar 28, 2006 #6

    Q_Goest

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    The well has a certain volume in it that's able to provide for this surge of gas you need. The volume your well has was sucked dry in a matter of minutes or hours. It took a few weeks for the well to bring the pressure in that volume back up. The conclusion from what you just said is that the flow rate of gas coming from the well is an order of magnitude or more lower than you need. It doesn't matter what volume you put in the system. From what you just said here, the well is incapable of providing sufficient flow regardless of the volume. Putting in a 50 gallon volume might suffice for a day or so but obviously the well would never be able to fill it in that amount of time, it would take weeks or even months to fill that volume to a few psi.
     
  8. Mar 28, 2006 #7
    Thanks Q_Goest.

    I figured as much too. Every 21 days the well would recover only 8 psi or so. The boiler needs more than 5 ccf for one day's heating cycle. It's impossible. I would need a HUGE tank, maybe 10,000 gallons. It would be cheaper (but a gamble) to re-drill the well deeper. My only other option is to try a compressor to literaly suck more gas from the well's underground supply formation. That's an $800 deal by itself.

    Anyway, thanks so much for your input. I will keep this post open for a week or so in case you (or someone else) has a better idea.

    jimoferie
     
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