Gas well flooding 1

[MrHitman]

History- I am a civil engineer working on an old lanfil which is now used as a methan plant and distributor to frito lay. we began well maintainance here this month for the first time in several years and we are having a few problems with pumping out the wells.

Problem- these gas wells are ranged from 25 -65 feet of depth and some of them are flooded with rain water from over the years and also muck from the garbage it is getting methane from is mixed in the water. standard sump pump will work for a moment but will almost instantly clog with muck.

Question- What kind of pump or method may we use to get water out and Keep water out of the wells, (especially the ones to which consistantly let water in), so that the quality of methane stays it's best

 

[MrHitman]

um... ya so thanks for ya'lls comments lots of help guys

 

[Ussuri]

Assuming your water is just groundwater, and you have a permeable surrounding soil have you thought about external dewatering.

You get resuspensioning pumps (the tend to be used in strom tanks to stop solids settling out) which might be used to get your muck into suspension so it can be pumped out by a submersible. Dont know what effect that will have on your methane.

Alternatively you might be able to use a positve displacement, sludge pump, type of arrangement. But that will depend on consistancy. This could be a diaphragm pump or a piston pump.

Is this permenant or temporary works? By the way, I have no idea on what affects quality of methane.

 

[MrHitman]

the only concern we have is getting water and in some cases about 20 foot a sludge out of our wells. that alone will improve the methane quality, other wise the only thing that will hurt it from pumping is if the pump makes sparks. but we try to avoid such things.
thanks tho for your help, I'm researching into them and will draw a conclusion from that. I just needed a starting point

 

[soiledup]

This is a 'bull in a china shop' approach, but if you really need to clear the wells, have you considered 'air'lifting' them with a lance and big air compressor. It will make a hell of a mess at the surface and is very very hard to control the arisings (if pollution is a concern), but it would certainly clear the wells.

Regards

Soiledup

 

[Ussuri]

Can you modify the bottom of your tanks so they have a conical bottom, at say 60 degrees. You can then have a pipe exiting at the bottom which is pumped with a diaphragm pump. This is a typical arrangment for removing sludge from primary tanks.

Not ideal when man entry is required but I imagine that with methane you wont have anyone in from a confined space point of view.

 

[MrHitman]

soiledup could u elaborate on what a "lance" would be in this situation. and how that mite work

Ussuri, I am trying to clean out gas wells that is only about 6 inches in diameter and 25-100foot depth which we would have no access too. we have a small diaphram pump which we've used for pumping out of our leachate tank and also used it on our smaller well but not for any of our deeper wells

 

[soiledup]

There are acouple of methods. The cheapest and easiest is to buy a large cylinder of compressed nitrogen (non reactive obviously) with a gas regulator, then attache a thin air line to the regulator and feed the line into the borehole. the benefit of this is that it is quick and cheap. A site technicain can do this. Remember to pump the air line up and down. As the air line is very thin, maybe half inch diameter and quite rigid it is possible to push it into the stiffest of blockages / slurrys. Then release the gas and stand clear. I've used this technique many many times here in the UK to re-instate old boreholes that have silted up / blocked up.

Try typing 'air lifting on boreholes' into the google to see what comes back.It is abit more complecated and would involve positioning a drill rig back over the borehole to lower in metal rods through which we feed the compressed air. Again, this is obviously one step further involving more cost. It can be cheaper just to redrill a well adjacent.

 

[cvg]

why don't you ask a well driller to come out and look at the problem. They should have numerous methods they can use to rehab the wells. Some ideas might be surge block / surging; backwash using compressed air (airlift); hydraulic jetting; swabbing; and chemical treatment for deflocculation/dispersion of clays and silts.

 

[jmrosell]

I would suggest getting a non-clog solids pump that is used all the time for sanitary sewer bypassing. It should be able to handle the sludge and garbage as long as it isn't anything too large. as for your worry of spark, you should be able to get hose long enough to get you out of the range of fumes. however, this will increase your head loss. as for keeping the water out, first you need to determine where the water is coming in from. if there are only a few spots you can drill and use and injectable foam to help seal the area. if it is a larger area there are sprayable coatings that help keep water out. also, there are plastic infiltration covers that you can put on the top of the well that work very well at keeping rainwater out.

 

[MrHitman]

Cvg, a good idea you have, interestingly enough we contacted a vacuum company, the same people that clean pipes for oil company's and such, and their equiptment wasn't designed to go as deep as our wells are unfortunately. as far as well drillers I will look into that more with my supervisor although I believe he's considered the idea. my belief is that the reason we haven't done that yet is due to the reason that our county is under a budget cut rite now so we are having to maintain these wells with very few funds.

 

[MrHitman]

Jmrosell, could I ask u to provide a little more information, and possibly your recomendation of a company that sells these, or brand names so we can research these pumps.

 

[jmrosell]

we use godwin pumps. here is their website.

http://www.godwinpumps.com/

i believe they can give you more direct information for their area.

 

[MrHitman]

do u know if they are effiecint for going down a 4-6in diameter, vertical pvc pipe, possibly bent, with 25-105 feet of depth?

 

[jmrosell]

it would make the job tougher, but i think they should be able to do it. you would have to check with the manufacturer to make sure.