ESP issue

[BA Joe]

Hi Folks,

Just installed an ESP after a workover for a heavy oil reservoir. Upon turning on ESP, the Pi and Pd increased and THP stabilized, after 1 hour, THP suddenly dropped gradually to Zero in 15 mins.

Turned to gas lift and the well flowed though at low rates. What could be wrong with the ESP?

Thanks

 

[LittleInch]

It's broken?

Has the motor tripped?
Cable fault?
Pump clogged with sand, rocks, dirt??
what's Pi and Pd?
What instrumentation do you have downhole or no the ESP itself?

Give us something to work with here.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[BA Joe]

Thanks for the response.
Pi is intake pressure, Pd is discharge pressure.
I doubt its cable because upon turning on ESP, we are able to receive data from the ESP gauge.

Can it be sand clogging? we do have screens at the intake.
Can it be the fluid is too heavy? But ESP has been used for such heavy fluids successfully

How will you know when the pump impeller is broken?

Please, What other details do you need?

 

[LittleInch]

Can you give us the time plots for Pi(I assume this is pump inlet) and Pd (Pump discharge) so we can see any trends. And THP.

voltage and current measurements for the pump.

The pump curve wouldn't go amiss as would the fluid data ( SG, water cut, gas fraction, bubble point, BHP, that sort of thing)

Sand or rock clogging of the impellor sounds like the most likely at the moment.

Broken impellor is more like when you're fairly certain the motor is going round, but nothing is happening fluid wise.

A diagram always helps.

How easy is to pull the ESP out?





Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[BA Joe]

Thank you for the insights thus far.
Sand clogging & broken impeller are plausible reasons.

It is a newly installed ESP after a workover, hence pulling out the ESP will call for another workover .

Thank you.

 

[waross]

THP suddenly dropped gradually to Zero in 15 mins.

Is it possible that the pump was passing sand that has built up a column of sand in the discharge tubing?
If the sand is not being carried completely out of the tubing with the hydro-carbon flow it may have blocked off the flow.
Is the ESP at exactly the same depth as it was before the workover?
Has the ESP been re-installed lower than before the workover?
BTW, what were the Pi na the Pd after the THP dropped?

Turned to gas lift and the well flowed though at low rates

This suggests a restriction more than a broken impeller.
Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[BA Joe]

Hello, thank you for the response again.
* There was no ESP prior to workover, it was producing on Gaslift, but client wanted higher rates.
Even now, without ESP, it is still able to produce oil with gaslift at low rates and sometimes intermittent.

See below snapshot of data

Pi Pd THP(psi)
1770.6 2571.3 580 100% BSW
1799 2571.9 580 100% BSW
1806.4 2564.8 0 100% BSW
1849.5 2567.7 0 No fluid on surface
1867.3 2570 0 No fluid on surface
NEXT DAY
1537 2514.2 0 No fluid on surface
1562.8 2553.7 0 No fluid on surface
1505.7 2527.2 0 No fluid on surface

 

[waross]

* There was no ESP prior to workover, it was producing on Gaslift, but client wanted higher rates.

This may be similar to a failed SAGD operation some years ago.
Management wanted higher rates, and kept posting production targets.
Over-pumping to meet unrealistic production targets destroyed the formation.
In a SAGD operation the result of over pumping may be a destroyed sand formation, excess produced water and poor production.
A similar problem may occur in deep water wells when over pumping starts to move sediment towards the well and the sediment eventually plugs off the water flow.
The higher pumping rate may have moved sand ahead of the pump and blocked off the flow to the pump.
Does this correlate with your field data?

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[BA Joe]

Thank you.

A suggestion we got is to bullhead the column with diesel and xylene (mutual solvent), then start up pump again.
It is hoped that the fluid will help the pump to pick up and start pushing out hydrocarbon.

How realistic is this? Will it achieve the objective?

Please, What solutions can you propose to the whole situation?

 

[LittleInch]

Well from that data if indeed Pi and Pd are taken from inlet and outlet of the pump then it looks like your pump is working well, though where the fluid is going or whether your pump is dead heading isn't clear.

However we know virtually nothing about your well so it's impossible to second guess remotely.

Is there maybe a leak from your tubing back into the well? is your annulus pressure changed?
Where is the packer?

If you're getting some flow via gas lift then I don't think it's blocked so much anywhere that forcing a mixture of diesel and Xylene (horrible stuff) is going to do you any good.

I think you need more experienced help on the ground.

Or give us lots more information

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[waross]

What is the static head at the pump?
Can you check the discharge fluid on gas lift for sand content and Specific gravity.
If over pumping has moved a lot of sand, the entrained sand may have raised the SG to the point where you don't have enough head pressure to move fluid.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[sraesttam]

I recommend the following:

Gather wellhead amps and volts or VFD output volts and amps. Multiply them together and divide by 746. HP = (Volts * Amps) / 746

Now plot your horse power as a function of time.

By looking at any common radial flow or mixed flow pump curve, we can see that if fluid flow through the pump also increases, the brake horse power also increases for the majority of the operating range.

Therefore, if you have a hole in your pump housing, discharge head, or tubing, the flow rate is going to increase and motor horsepower will increase regardless of surface flow rate changes.

If you have a plugged pump discharge or tubing, your flow rate going through the pump will be zero, and the motor HP will decrease.

If you had a twisted shaft and not able to develop enough head to lift the fluid to the surface, the flow rate will be zero the motor HP will also decrease.

I would ASSUME that since you have a higher end sensor with discharge pressure, you also have a motor oil and possible motor winding temperature sensor. What are these readings telling you?

The motor controller is usually designed to shut down the ESP in a high temperature condition. If you have no flow through the pump, and no auxiliary recirculating equipment, your motor temperature is going to spike up and the pump will shutdown on over-temperature. If you never had an over-temperature shutdown, it is likely that you have a hole in your tubing.

When you say tubing pressure do you mean actual tubing pressure on top of the well or do you mean flowline pressure? Another small thing that can happen is that you can have a casing check valve that gets stuck open allowing fluid to circulate from the christmas tree on the surface back down the annulus. Though, I'm not really familiar with running gas lift and packers in combination with ESP equipment. If you had a packer above your ESP, I can't envision that you would also have a casing check valve.

There are a whole lot of problems that can occur when running ESP equipment. They can accidentally run the wrong pumps with the wrong stage design, run the wrong number of pump housings, or switch the order of the pump housings on tapered ESP designs.

 

[waross]

Actually the formula for HP is:
Root [(Amps x Volts)[sup]2[/sup] minus (Magnetizing Amps x Volts)[sup]2[/sup]]/746
The Magnetizing Amps change very little with load and will cause significant error at low loads.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[BA Joe]

Hello everyone,

I really appreciate your posts on this issue. I did the above calculation as suggested.

The results seen is "NO FLOW with DECREASING HP". Also I noticed the temperature spikes but yet to confirm if it led to the shut down.

Like I said earlier, it is not likely a hole in tubing because the well was able to produce on gas-lift. It is more likely a plugged pump discharge or tubing.

Please kindly recommend possible solutions.

Thank you.

 

[LittleInch]

Pull the ESP out.


Anything else is a sticking plaster.

Keep it on gas lift while you bring the rig in.

Any drawings of what the bottom hole structure looks like?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[BA Joe]

We will get a sample of sludge and crude, send to a Lab to see what chemical can dissolve it and also compatible with the crude.

Hopefully we get a solvent than can dissolve whatever is blocking the pump disharge/tubing. RIH, Pump down and soak.

If it does not work, then we will have to pull out ESP.

Thank you all for your opinions and suggestions.

 

[waross]

Please share your findings with us, Joe.

Bill
--------------------
"Why not the best?"
Jimmy Carter