RE: Hmmm, sounds interesting!31 Jul 2025 14:37
Hi gmed,
Basically they "could" say run coil tubing (your hosepipe) into the wet section of the wellbore to drain as much of the condy/liquids out, BUT the issue with that is that it would likely fail, why ? because what you would end up with is the coil tubing filling with "just" liquids, and the only driving force for that liquid column inside the coil tubing is reservoir pressure.
It is almost nailed on, that the density of that liquid column inside the coiled tubing to surface, would be greater than the pressure trying to drive it out.
For example, typically condensate has a ballpark gradient of +- 0.2 psi/ft, so if you had a piece of pipe 5ft long stood vertically with a cap on the bottom, and filled it with condensate, then the pressure/weight of that 5ft column would be +- 1psi, the wells at SLBY are give or take 7000 - 7500 ft deep, so if you had a coiled tubing filled with condensate from bottom of well to surface, the pressure/weight of that column at the bottom of that tubing would be +- 1400-1500 psi, so the natural reservoir pressure at say 7000ft would need to be greater than the weight of that column, meaning greater than 1400-1500psi, which is almost certainly a bit more than the current reservoir pressure.
Lets assume the current reservoir pressure is 90 barg or around 1300 psi, then this means the reservoir pressure is short by 100-200 psi driving pressure to push that liquid out at surface, the liquid top in the tubing would be something like 1000 ft below surface. and the pressure in the tubing above the top of liquid would be zero.
So how do you overcome this ? you run a "velocity" string. which is a much smaller production tubing than what is inside the well right now, this means that when you open the well the same amount as with the older & larger tubing, the gas travels at a much greater speed on route to surface, and what that does is it helps to bring stored/banked liquids out with that high speed flowing gas, likely as a mist and slugs of liquid.
By doing it this way, the column inside the velocity string weighs much less than a column of just liquid, because it is a combination of gas AND liquids, therefore if 1/3rd of the column was liquid and the rest was gas, the same 7000ft column would be around 500 psi of liquids weight and the rest as gas which is next to nowt, so now, if you have 1300 psi reservoir driving force/pressure, and the mixed gas & liquids column in the tubing is say 500-600psi weight, you have a driving force excess of around 600+ psi, meaning it can easily continue to healthily produce with a good surface flowing pressure.
You may be thinking, well in that case pump/lift the liquids out, but this would be hugely difficult to manage as it is highly reliant on how quickly the liquids in the near wellbore reservoir can replenish/flow into the wellbore to the lift pump, and is highly likely to be almost impossible to work long term.
I have tried to keep it in "layman's" terms to unde
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