How do you calculate velocity
How do you calculate velocity
(OP)
I have a 4 inch cup pid behind it I have 7500 kpa.In front of it I have 2500 kpa. when i start the well up it takes some time before the pressure on the 2500 kpa side reaches 6500 kpa so you still have a diffrental of 1000 which pushes the pig but until that happens I would think the pig is moving quite rapidly? 2 phase flow of gas and fluids.





RE: How do you calculate velocity
With your rapidly increasing downstream pressure, the constant acceleration assumption is even worse than normal. Another twist is that the mass of the stuff in front of the pig is also ever changing, but you can make assumptions about the rate of change that aren't horrible.
I've been doing this silly arithmetic for years and have never been close to predicting an actual duration (an therefore a velocity). I keep trying because my clients expect it, but I always start with a serious disclaimer.
David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com