Airlifting well for redevelopment

[vwguygti]

Hello all,

In a previous thread of mine, I asked questions about developing my newer well that I don't believe was properly developed.

My latest theory is the 1/8" x 4" slots at the bottom 20' (280'-300') are clogged and water has to come up to near static and dump into the 4" casing at 22' from the surface (static 10'-15').

After discussing it with my well company who drilled it, they got back to me and essentially agreed and thinks the steps are to pull the pump, possibly lift the 4" PVC casing and do an airlift. The cost seems astronomical (T&M - estimate if all goes well 5-6k, and if they pull the casing and it gets stuck, they bring the driller back in, which could bring that cost to over 10k pretty quickly) I don't think pulling the casing in necessary. and an airlift alone could solve this and further develop the well.

I have done some research here and other sites and it seems like there are a couple ways to do this. Could either case around the 4" pvc temporarily with 5" PVC and drop a 2" inside the 4" and blow through the 2". Or drop the airline into the 4" casing directly and let it geyser. Is this accurate? Being a 300' well and 10'-15' static, what size compressor would I need? I should be able to get a large diesel tow behind locally, otherwise I'm not too far from Spokane to get something larger.

Any advice/information would be greatly appreciated! Thanks in advance.

Edit: see LINK for original post that better describes the well.

 

[Fitter30]

280'- 22'= 258'/ 2.31= 111.5 lbs of standing water pressure.
Sch 40 220lbs max working pressure
Sch80 320lbs max working pressure
Pvc pipe is not made for compressed air it's extremely dangerous can explode turn into shards of plastic.

 

[Sponsor]

 

[LLigetfa]

I am doubtful that air-lifting by itself would do a very good job of unclogging the screen. Ask the well company if they could run a surge block up and down to clean out the slotted casing prior to air-lifting. I have also heard of sewer jetting well screen and have worked with both small jetters on 2/8" pressure washer hose for residential and large jetters on fire hose for clearing industrial sewers. Fire hose bursting pressure can be as high as 1600 PSI.

 

[Reach4]

Air is sometimes used to blow sediment out of an older well.

You might want to edit in a link to your earlier post, or add a digested description of your well.

"My latest theory is the 1/8" x 4" slots at the bottom 20' (280'-300') are clogged and water has to come up to near static and dump into the 4" casing at 22' from the surface (static 10'-15')."

I mostly did not understand that sentence. I was thinking 1/8 (0.125 inch) slots in a well screen are bigger than usual.

 

[vwguygti]

Air is sometimes used to blow sediment out of an older well.

You might want to edit in a link to your earlier post, or add a digested description of your well.

"My latest theory is the 1/8" x 4" slots at the bottom 20' (280'-300') are clogged and water has to come up to near static and dump into the 4" casing at 22' from the surface (static 10'-15')."

I mostly did not understand that sentence. I was thinking 1/8 (0.125 inch) slots in a well screen are bigger than usual.

I will add a link in my original post of the thread that better describes my well.

As for the slots - per the drillers well log, they cut 1/8”x4” slots via skillsaw throughout the last 20’ section of casing. The well is in granite and has no screen

 

[LLigetfa]

From your description of the well in your other thread, my guess is it has a bad seal or no seal between the steel casing that is only 38 feet deep and the PVC casing. Possibly there is no seal or a bad seal between the bore hole and the steel casing and surface water may be contaminating the well.

 

[vwguygti]

From your description of the well in your other thread, my guess is it has a bad seal or no seal between the steel casing that is only 38 feet deep and the PVC casing. Possibly there is no seal or a bad seal between the bore hole and the steel casing and surface water may be contaminating the well.

I brought this up to the driller and they said they have a proper seal between the hole and 6” steel case. They drilled a 10” bore to 38’, set the 6” pipe and sealed between with bentonite. They said they hit granite at 30’, so the seal extends 8’ into the granite.

 

[Valveman]

If it is a rock well, drilled in granite, it should not need casing. I would just pull the 4" liner out, blow the well clean, and reinstall the pump without the liner. If the liner is needed because the well is collapsing the rock is not stable and you need to set the pump above that spot anyway.

 

[vwguygti]

I think their logic was it being decomposed granite and salt and pepper granite, it would keep the well going/pump protected in the event of collapse.

Problem is, the level in which they hit granite is 30’, I wouldn’t want the pump that high.

They want to do exactly what you are suggesting, just reinstall the casing after blowing the well out. Is there an available tool out there to be able to reach down to grab onto the 4” case?

 

[Valveman]

Yeah they will be able to get a grip on the 4" liner. If the granite started at 30' it should go all the way to the bottom. That means only 30' of casing is needed as the rest is drilled through rock and the pump can be set close to the bottom. If the granite is "decomposed" and caving in, it will keep caving in on the liner. A gravel pack in the annular space between the liner and well wall is how we keep the loose stuff from collapsing in. But the liner would need to go all the way to the top to be able to gravel pack.

 

[vwguygti]

Got it. So if in fact it is caving in around the 4” liner, it may either be difficult to pull or once pulled create a scenario where they would need to redrill?

The granite does go to the bottom (30-105’ decomposed granite, 105-300’ salt and pepper granite). And the 4” liner goes from 20’ to 300’

 

[Valveman]

Got it. So if in fact it is caving in around the 4” liner, it may either be difficult to pull or once pulled create a scenario where they would need to redrill?

The granite does go to the bottom (30-105’ decomposed granite, 105-300’ salt and pepper granite). And the 4” liner goes from 20’ to 300’

Maybe not re-drill just air-lift or bail. Liners always bothered me. If it needs lining, something is sluffing off. Just as well do it right and case to bottom and fill the void with a gravel pack so nothing can sluff off.

 

[vwguygti]

I wish that was an option presented to me when it was drilled!

 

[Valveman]

I wish that was an option presented to me when it was drilled!

Most rock wells stay open without a liner. It maybe a rare occurrence in that area so they just don't case to the bottom. Might be one of those occasions where they need to learn to case and gravel pack to keep the hole open. You paid for a good well. They need to provide you with a good well, no matter what it takes. Learning things in the drilling business is very expensive for reasons just like this.