Plunger lift safety

considerations

• Presentation is meant to bring awareness to safety set points and shut

downs

• Is it ok for “heavy” plungers to be “allowed” to travel as fast as light ones?

• Should metal selection play a role in shut down settings?

• Are your shut down settings enabled?

• Are your shut down settings “blanket ordered”?

Every time a plunger well is shut in for whatever the reason – the situation is

worsened the longer the well is shut in.

800.0

1000.0

1200.0

1400.0

1600.0

1800.0

2000.0

2200.0

-1.5

-1.0

-0.5

0

0.5

1.0

1.5

0.000 13.889 27.778 41.667 55.556 69.444 83.333

Is your logic set up ok?

Is this why plungers break?

Hydrates

Too Slow Target

Gas Slips By Plunger

May Never Reach Surface

Too Fast

Wastes Well psi

Damages Equipment

How fast is too fast for the lighter plungers?

How fast is too fast for the heavy plungers? Arrivals faster than 1000 ft./min is mostly a waste of energy not necessarily a

point of damage.

Gas velocity/pressure Velocity increases

significantly as pressure is

reduced

Point – If it becomes

necessary to blow the

well be aware of the

impact that has on the

velocity of the gas and

therefore the plunger.

Point – If the well has

been shut in for an

extended period and is

going to be brought on

to a low pressure

system be cautious of

the plunger travel

speed

Things we can control to Reduce Impact

Energy

1. Mass (Reduction in Mass = Reduction in Impact energy)

2. Ensure your well is “optimized”

3. Improvement to materials and springs

4. Preventing “lifts” during high energy situations

5. * mass reduction is often overlooked as a means of impact force reduction

Assessing Dangerous

Arrival Speeds

• In order to assess when an arrival is going to cause damage

or a catastrophic failure we should consider

• Spring in Lubricator/Spring in Bottom Hole

• Weight of Plunger (focus area)

• Material of Lubricator

• This will become important in the case that the spring is

damaged

Assessing Dangerous

Arrival Speeds Example

Operating

Window – In

this case the

spring is

collapsed at 14

m/s and force

on the

Lubricator

begins, this ties

directly to the

weight of the

plunger.

Assessing Dangerous

Arrival Speeds Once the Spring has

been damaged you rely

on the yield strength of

the material which can

vary from manufacturer,

best practice is to

contain the Kinetic

Energy of the plunger

by reducing speed and

weight where possible

however for safety

lubricator material

should be reviewed.

Weight vs velocity

A 9.8 Lbs plunger @ 1000 Ft/min has the same Kinetic

energy as a 3.2 Lb plunger @ 1700 Ft/Min

1700

ft/min

1000

ft/min

psi

Do plungers need “speed limits” specific to mass?

Presentation is centered on mass and not specific to

lubricators or liquid brought to surface. It is about

the “ones that get away”

2000

ft/min

600

ft/min

A 30 Lbs plunger @ 600 Ft/min has the same Kinetic

energy as a 3.2 Lb plunger @ 2000 Ft/Min

Should plunger mass be considered in determining

shut down settings? Red Line represents constant

energy.

psi

Similar looks Some plungers may look the

same but different metals “can”

equal impact force reduction.

1000 ft./min = 2282 lbs. impact force [steel]

1000 ft./min = 1548 lbs. impact force

[titanium]

Different looks 1000 ft./min impact force 2338 lbs

2 7/8 Venturi ti

1000 ft/min. impact force 8510 lbs

2 7/8 triple pad

800.0

1000.0

1200.0

1400.0

1600.0

1800.0

2000.0

2200.0

-1.5

-1.0

-0.5

0

0.5

1.0

1.5

0.000 13.889 27.778 41.667 55.556 69.444 83.333

Pressure required for

large slug

Large slugs can promote high energy situations

Pressure required for

“optimized” slug

SCADA systems and stand alone controllers have shut down

settings in place that address fast arrival conditions. Should 1000

ft/min apply for everything including 2 1/16 – 3 ½ inch plungers?

Below is a list of average plunger weights traveling at 1000ft./min

• 2 3/8 Venturi ti – impact force = 1337lbs

• 2 3/8 viper – impact force = 3317lbs

• 2 3/8 dual pad – impact force 4257lbs

• 2 7/8 triple pad plunger – impact force 8510lbs

So what can you do to

minimize impact forces?

• Ensure your well is optimized. Maintain small liquid slugs and only shut in long enough

to meet the MINIMUM pressure required for a lift.

• Consider metal specs on surface facilities. Sometimes you get what you pay for.

• Consider plunger mass when setting your safety shut down settings. Mass reduction

alone can have positive impacts on production if liquid slugs are kept small, as well as

having drastic benefits to arrival impact forces.

• Make sure your safety shut down settings are “enabled”

• Regarding high speed shut down settings – is the concern the number? Consecutive

values? Or cumulative values?

• Is shutting the well in required?

Safety/profit

• With plunger lift wells – “the lower the flowing

bottom hole pressure, the more gas you make”

• With plunger lift wells – “the lower the flowing

bottom hole pressure, the SAFER you system

is”

• With plunger lift wells – “optimization and

safety work well together”