Vertical turbine lineshaft pump for deep well

[ccc123]

All,

I have a new project at which we have to install a vertical turbine line shaft pump for deep water well , the design condition for pump is : 450m head and 200m3/hr capacity . The well is drilled before two months , the contractor who driiled the well performed a pumping test at 60m3/hr and from the data of this test they got the values of specific capacity and transmassivity, depending on the test data, the owner of the well did his calculation and correlation to specify the above desing condition. My question : Can we depend on the data of the 60 m3/hr pumping test to specify a pump with much higher capacity (200m3/hr) or we have to conduct a pumping test at 200m3/hr and then to check the data if it's ok or not.

 

[d23]

If the 60 M3/h test was operated long enough to obtain a stable fluid level you should be able to calculate it however; if it was a short test you will need to retest the well.

 

[ccc123]

The test is operated long enough and they obtained stable fluid level , abouit 48 hours . So u think the data is enough to uggest the 200m3/hr capacity pump ?

 

[EdStainless]

You might be able to estimate from the well recovery after the pumping. Be careful, 3.5x is a stretch.

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[ccc123]

Dear EDStainless ,

Can you explain to me what do you mean by 3.5X is a stretch

Thanks

 

[d23]

ccc123

A 48 hour test should be enough to calculate flowing conditions at various rates.

I would suspect that the reference that "EdStainless" makes to 3.5X is the test at 60M3/hr verses the design rate of 200 M3/hr. Not knowing the reservoir that you are producing he may be correct that a calculated TDH for a 200M3/hr flow may not respond in a straight line or as a fixed productivity index (PI). Regrettably Darcy’s law for radial flow into a wellbore is a little beyond the scope of this forum.

You should be able to make several assumptions about your design without using Darcy’s formulas. You say they calculated that you will require 450 meters of lift at 200M3/hr. I don’t know the wellbore or test data you have, so the most simple thing that I can offer will be in the form of an example. As an example lets assume the static fluid level is 250 meters the design data becomes:

Static FL = 250 M
Producing Fluid Level = 310 M
Test Q = 60 M3/hr

To predict the fluid level at 200 M3/hr it becomes:

PI = 60 M3/hr / (310m – 250 m) = 1m3/hr per 1 meter drawdown

200 M3/hr = 250 M static + (200 M3/hr Desired / 1 M PI) = 450 M net lift required

For this example I assumed a PI of 1 and designed the pump net lift based on this. Once you select a pump and number of stages required for the actual design data, recalculate the lift required if the actual PI is only half of the actual design PI. Using your pump curve see what the flow would be with the higher net lift requirement.

In most cases you will find that a pump designed for a well or formation that is capable of producing a rate of 200 M3/hr will most likely not change much once you make several “what-if” comparisons or iterations because the PI will be an extremely high number or ratio.

FYI:

You do need to account for any casing pressure or tubing pressure they may have had during the operating test and/or static test. If there is any gas you will need to account for the gas volume or area required in the pump.

TDH is the sum of net lift, friction loss and surface pressure required. You will need to consider friction loss and new surface pressure requirements too.

 

[ccc123]

D23 , I would like to thank you a lot for your help , because you gave me good information.

I know I bothered you alot , but in case u have any PDF files regarding the calculationS of pumping test or any good information , especifically the mathmatical examples , that can help in assumption and calculations ,can u please send it to me.

Again , I appreciate all you help

Regards,

CCC123

 

[Artisi]

To be able to establish if 200m3/h is possible from your well we would need a lot more information than what you have given other than the well driller has pumped the well at 60m3/h for 48 hours and has advised you that 200m3/h is possible.
The basic info. required would be
1. is it a confined or non-confined aquafier?
2. what is the standing water level?
3. what is the draw-down level after 48hrs of pumping?
4. were any observations wells drilled to monitor drawn-down away from the pumed well?
5. what is the depth of the well and what is the pump setting?
6. what is the well-screen capacity?

I have attached 2 links for you to better understand what is needed to calculate the flow into a well etc.

In both these links it mainly addresses shallow multi well-point installations but you can modify the cals. to suit a single well installation at any depth.
There is a lot of overlap between these links and possibly a few differences in the formulae - I haven't compared them so can't comment.
The first paper from Ciria was authored by a very experienced engineer with an extensive background in deep-well pumping.

http://www.ciria.org/acatalog/r113.pdf#search="wellpoint dewatering calculations"

http://www.broward.org/pprd/exhibitiiirev.pdf#search="wellpoint dewatering calculations"

Trust this helps to expand your understanding to your question.

Phitsanulok
Thailand

 

[Artisi]

One other comment worth a mention is, if the well driller has experience in the area where your well has been drilled - he might have enough prior knowledge to advise on the expected flow rate.

Phitsanulok
Thailand