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Pressure drop issue

Pressure drop issue

Pressure drop issue

(OP)
I´m having an issue on a job we ran involving hydraulics and leak pipe.

We ran a pipe downhole 10,000 ft, once reached bottom we tried to pressure up the pipe to 3,500 psi so our tool (located at the bottom end of the pipe) could be activated and setup. We noticed the pressure dropped instantly once we stopped pumping.

We noticed there was a leak 4,500 ft (+/- half distance), and tried to pressure up to 5,500 psi with no sucess. We pumped fluid (1 BPM) for an hour holding the pressure to 5,500 psi and still didnt notice our tool being activated, somehow the pressure didnt reach bottom.

Can anyone tell me what happened? Is there any theory or mathematical explanation I could relay on?

RE: Pressure drop issue

I will exhaust all logic before trying for a mathematical explanation. You are trying to pressurize a system with leakage in place and that is the issue or I terribly missed something.

 

RE: Pressure drop issue

From the description you provided, you have a relatively large "hole" somewhere down your pipe. By "hole," I mean a gap, crack, break, or other fissure in the pipe that is allowing your fluid to escape the pipe.  This "hole" is large enough that pressure is not being maintained, resulting in your equipment not being activated. The size of the "hole" apparently is large enough that the fluid you're pumping can't seal it and is just running out the "hole."

Unfortunately, your options are rather limited. You could try continuing to pump your fluid in the hopes that you will eventually be able to pressurize the system.  However, there is no guarantee on this and you could end up creating a much bigger problem.

Not being familiar with your industry, I'm not sure if it is even possible to repair the pipe.  If not, hopefully you can at least retrieve your equipment.

In any case, I'd suggest a rigorous review of what happened that caused the leak so as to prevent this problem from recurring.

Patricia Lougheed

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RE: Pressure drop issue

I assume what you are getting at is even though there is a leak, if you put enough flow in (and build suitable pressure), then the tool should work.   This is similar to why water flows out the end of a garden hose even though there are leaks all along it.

I would start by doing a pressure drop calculation based on flowrate for the length of hose to the leak.  This will calculate the pressure immediately next to the leak, and hence the pressure to the tool.  If this comes out higher than the pressure to activate your tool then this is why.

RE: Pressure drop issue

As cpretty says, your first check should be to calculate the expected pressure drop you get by flowing 1 BPM along 4500 ft of pipe.  That will tell you how much of your 5500 psi is reaching your tool down at 10,000 ft

It might help if you tell us what pressure your tool needs to be activated ?  Is it reasonable to assume 3500psi should be enough ?

RE: Pressure drop issue

Maybe im missing somethign here, but assuming water is the fluid your looking at about 4350 PSI of pressure if you just pour the water into the pipe, you should not even need any pumping cause gravity should do the job for you. unless of yourse you meant you need 3500-5500 PSI in addition tot he static head.

Again as a few people ahve said though its the gaping hole int he pipe thats causing your problem, id pull that string out and find out what ahppened.

Either that or your tool fell off the end of the string, one of those options is my best guess.

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