abandoned water well useable?

Discussion in 'Geothermal Loops' started by SolarSPOT, Nov 26, 2011.

  1. SolarSPOT

    SolarSPOT New Member

    I've discovered an abandoned water well on newly acquired land in south central New Mexico. Hearsay is that it was drilled 4 or 5 years ago and was abandoned because of insufficient water production. The 7-in-diameter borehole does not have a casing, and goes down 720 feet. Water starts 230 feet down. Overburden is minimal/shallow.

    What's the best way to tap this great resource for heating and cooling a new house near the borehole? Open loop, closed loop, one closed loop, two closed loops, etc.?

    What's the easiest, quickest, but accurate way to determine the capability of this resource? rules of thumb like 1 ton per 200 vertical feet? or field testing? What are the costs?

    I will need to compare the costs of additional boreholes vs. reducing the building loads by changing the design to include more insulation, better windows, air sealing, passive solar, etc. How close must the rating of the well match the building heating and cooling loads?

    If an additional borehole is needed must it be the same depth? or can I drill it shallower, say to 400 feet, and balance the flows with a header approach?

    Can I avoid the cost of drilling additional boreholes by going to a dual-source (ground and air) system? Who makes such units?

    Who can do the analysis, and who can do the work for me in the Truth or Consequences to Las Cruces area of south central New Mexico?

    Thanks.
     
  2. Forum Admin

    Forum Admin Administrator Staff Member Forum Leader

  3. Blake Clark

    Blake Clark Member

    Lots and lots of variables, but this might get you started.

    With a standing column configuration, a gross rule of thumb is roughly 100 ft of water per ton. So, maybe 4 to 5 tons capacity. Standing column is a semi-open system that circulates the ground water from the bottom of the well to the top. With a well that deep, you'd probably need a porter shroud rather than placing the pump all the way at the bottom. With the static head at 230 feet, though, you're looking at 1.5 to 2.0 kw minimum for pumping energy for a 5 ton unit, which would take a significant bite out of your system COP.

    With an open "pump and dump" system, the capacity is entirely dependent on what the well can produce, with a rule of thumb at 1.5 gpm per ton. Again, with a high static head, you'd lose quite a bit of efficiency to pumping energy.

    Another option is vertical closed loop. Usually vertical boreholes are grouted after the U pipe has been inserted. As for capacity, someone more familiar with local soil conductivity would need to chime in on the capacity of a 750 ft vertical loop. My guess is that it would be significantly less than standing column, but I'd guess you'd be in the 2 to 3 ton range. Pumping energy would be minimal with a closed loop.

    Hope this helps think about your options.
     
    Last edited: Nov 30, 2011
  4. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    I have never had my boots on a job

    in NM. In fact I have only flown over it. From what I have learned it is warm and dry.

    I, living with Lake Erie as my back yard do not like to pump and dump or otherwise mess with aquifers for heating and cooling. Water will be the next oil or food if we keep bio-engineering the planet without it's permission. Have no fear for the Planet as it will protect itself, instead worry about the inhabitants.

    [ Gets off soapbox ]

    If I get your climate correctly, you would be cooling dominate.

    Do you have a building or just the hole in the ground?

    What ever your answer unless you have a working domestic water well you will want one. So if the first 7" hole does not provide enough potable water you are going to need at least one more hole. It would seem to me if this is a relatively new hole the JHA would have a record of the hole and maybe a drillers log. Go ask them.

    If you have a building, (with or without) domestic water then we can modify the building to match what the hole can do with a closed loop, or build the building to that capacity. We can as you noted take what we get from the hole and add more.

    I know of a guy in NM that cools with solar panels. Google Bristol Stinkney. If you can not find him let me know.

    What the hole will provide in BTUH depends how much pipe can be cramed in the hole. I am not a well guy but I do get heat transfer. I would think with a fused U-bend one could cram 1" or 1 1/4" pipe to the bottom of the 7" hole and back. That is 1,440 feet of pipe with most of it wet plus the header to the building. That gives you a lot of BTUH available. Not being a well guy I would think you might need to grout and case parts of the system.

    I do not know of a combination air/water source heat pump, but I do not know everything.

    Since the hole is there I would plan on using it. What it will gain vs cost to improve is just arithmetic. If you wish I can help you crunch the math.

    Your screen name says it all, but I agree that hole in the ground can be helpful.

    I hope I hit all your Q's but if not type back.

    I seem to remember a place in NM called Quartzsomething that turns into an winter haven for boon-docking RVers in the winter.

    Good luck

    Mark
     
  5. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    We just recieved a memo from MDE maryland department of the enviroment laying out new rules for class 5 injection wells. This includes geo return wells. The new rules specify that another layer of permiting must be done to get authorization, as well as engineered drawings and specifications. This will kill open loops in MD. No PE is going to stamp a design and be held accountable for a widgit that has so many variables that they can not control the outcome of.

    I am neither a proponant or detractor, but if one state at a time moves in this direction due to pressure from the feds who regulate clas 5 injection wells the pump and dump we all love to hate and its associated benifits and risks will soon go the way of the dinosaur.
    Eric
     
  6. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    I'm a P.Eng.

    And I would sign it (exceptfor the border between our countries):)

    Those of us that are confident in what we do, make money taking on risks. That is the entire point I believe. Take the risk away from the regulators that don't have a clue. Buy some expensive insurance policies. And begin signing. Well...not quite that simple.:D

    Don't find a big company engineer. They won't be allowed to do anything outside of established (ie conventional 30-year old thinking) doctrine. Find the small firm guys.
     

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