How long should it take to pressure up 8000 ft of pipe to 10000 psi with a low pressure and high pressure pump
I am curently doing a test of Wellhead equip that takes 45 min. I fill it at 80 gpm and no pressure, then take it to pressure with a triplex pump putting out 10 GPM. If I instead fill the work with 18 GPM and 4000 psi, then take it to pressure of 10000 psi @ 5 GPM, will I cut my testing time at all. What is the formulae for this? I was told that water has a compression rate of .341 Gal per 1000 psi. Does that mean that it would only take 3.41 gal to take 1000 psi of water to 10,000 psi? How do I calculate this?
There are a number of things to consider in doing the
1. Water is considered to be incompressible. At 40MPa [5800psi] or a depth of 4km the change in density is only about 1.8% [1].
2. You also have to be concerned about the expansion of the pipe itself. The change in volume across that range will be even greater than the change in density of water.
– What is the diameter of the pipe?
– What is the wall thickness?
– You need to confirm your safety factors on the design before doing this test.
If the system takes 45 minute with a steady state rate of 10gpm to reach 10,000 psi and we assume no changes in volume due to the metal stretching or change in density of water.
It will take the 18 gpm pump 10 minutes to get to 4000 psi while the 10 gpm pump would required 18 minutes.
To increase the pressure from 4000 psi to 10,000 psi will take approximately 54 minutes. This is a 6000 psi change at one half the base rate.
So the simple appears to be NO!
This is because your are pumping at a much slower rate for the vast majority of the time necessary to achieve the final pressure.
As a side note to actually reduce the time pump at 18gpm to 7000 psi before converting to the 5gpm pump.
Niel Leon
Community Developer – Engineering.com
