Plunger lift is an increasingly popular form of artificial lift
that energy producers use to help lift fluids from their wells.
In this video I'm going to explain how plunger lifts work using this demonstration model.
Plunger lift is a great option for artificial lift. It's often the first form of artificial
lift producers use because they can employ it without a large expense or a workover rig.
It's more cost effective than pcp and rod lift and can typically be installed in about a day.
This model is simulating gas-assisted plunger lift.
First, let's identify what each piece on the model represents.
Above the surface would be the "Christmas tree." Then you have your lubricator
and right here would be the control valve.
This represents compressed gas being injected into the casing. So,
that pressure travels down the well and it enters the tubing through perforations.
It travels down the casing and enters the tubing, pressurizes the well.
In the state it's in now, the surface valve is closed.
The plunger is at the bottom of the well. There is some fluid that's on top of the plunger right now
so this would be considered a "loaded state," so the well is loaded with a column of fluid.
The style of plunger that we have in there right now - it's a dart style plunger - it's able to
fall against flow. So, if you have higher liquid rates you can use this style plunger.
As the surface valve opens that pressure is going to bring the plunger and this column of fluid
to the surface. So that valve opens up. That pressure that's built brings the plunger and
the column of fluid up. That plunger is able to still fall against flow so now
there's no column of fluid, uh, so, the valve shuts on the surface.
The plunger falls to the bottom of the well and you can see that column of fluid
and gas begin to come up and build on top of that plunger
so the producer would have a set cycle time for the plunger and that's just determined by
the fluid rates the pressures once the valve is opened and it brings that column of fluid up
as long as this valve is open it's called it's in free flow
or after flow and that's just how long that stays open before it then shuts again.
So now you can see that plunger falling back down to the bottom of the well again.
If it's a pneumatic valve they could still have electronics controlling it and determining when
it's going to open just using a solenoid valve but it could be looking at casing pressure.
When casing pressure builds to a certain point it's then going to open up the surface
valve allowing that plunger to come to the surface with that column of fluid.
They may also have it set up just on a timer
where it runs you know several cycles a day and stays open for so long for after flow
and that's really again just determined by the fluid rates and the the makeup of the well.
If a producer ever wants to change the type of plunger that they're using if fluid rates have
decreased or they're wanting something different out of the plunger lift system
there will be an auto catcher on the lubricator and so when the the plunger comes to surface
it will catch the plunger and not allow it to fall back down hole. That way they can
take off the top of the lubricator and retrieve that plunger and change it out for another one.
When the auto catcher is turned on, as soon as the plunger arrives in the lubricator the autocatcher
will catch it and not allow it to fall back down the hole.
So, you'll notice on the lubricator there's two outlets going into the flow line. That's
to allow the column of fluid on top of the plunger to escape and allow the plunger to
enter the lubricator fully. If if wasn't there, this top piece of tubing that column
of fluid would be stuck in the lubricator and it wouldn't allow the plunger to fully enter it.
So at the bottom of the tubing is the downhole spring assembly which is made up of a spring,
there's also a ball check at the bottom of the spring. It allows gas and fluid to enter the
tubing but it does not allow it to go back down and it's just a ball that sits on top of the seat.
So it allows things to come up through it but if flow goes the other direction it seats the ball
and keeps it keeps a column of fluid on top of the plunger and that just allows any gas that's
in the casing, if you're injecting gas, or even if you're not injecting gas, it just allows that
that pressure and that fluid to build on top of the plunger. That way when the the surface valve
or surface control valve opens up that column of fluid is there for the plunger to bring up.
I hope this was helpful in explaining how a plunger lift system works.
If you have questions about the controls or components of a plunger lift system
you can call your local Kimray store or authorized distributor.