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Perforation without surface Indication and Losses
02 October 2019
I would like to know if anyone has ever experienced perforating a reservoir sand without any surface indication nor losses into the formation after monitoring well for over 5hours, perforating guns were spent on POOH to surface.

If you have could you help answer the following questions?

1. Were you able to produce from the reservoir sand in question?
2. Would you advise a second perforation run?
3. Could it be an indication that we likely perforated a shale formation
4. Any other explanations you have to why we had no losses into the reservoir?
6 answer(s)
Kaluk
Well Site Drilling and Completion Supervisor
Greene's Energy Group
Total Posts: 7
Join Date: 12/10/19
Please note this typographical error... Drawdown the well to the required underbalance for inflow production test. IIf DP and extreme overbalance perforation, then pressure up the well to circulate perforation debris deep into the formation and create fractures around the perf tunnel. If DP but underbalance perforation, then flush the tunnels through cycle loading and unloading then drawdown until the well begins to flow.
Kaluk
Well Site Drilling and Completion Supervisor
Greene's Energy Group
Total Posts: 7
Join Date: 12/10/19
Please note this typographical error... Drawdown the well to the required underbalance for inflow production test. IIf DP and extreme overbalance perforation, then pressure up the well to circulate perforation debris deep into the formation and create fractures around the perf tunnel. If DP but underbalance perforation, then flush the tunnels through cycle loading and unloading then drawdown until the well begins to flow.
Kaluk
Well Site Drilling and Completion Supervisor
Greene's Energy Group
Total Posts: 7
Join Date: 12/10/19
It will be important to verify your drilling logs,RFT/DST to ensure you perforated the target sand interval The shape of the gun charges matter will determine how deep the perforation tunnel will penetrate the formation past the damaged near wellbore region. BH charges will create big exit hole in the casing and around the casing may not penetrate beyond the damaged zone. So may require some clean up, acid stimulation/fracking/packing. But deep penetrating slim hole charges may penetrate deep and connect the undamaged zone. All you need to do is to clean up/flush the tunnels with filtred brine and then drawdown the well to the required overbalance to initiate flow. Your inflow test will show if you had perforated the gas cap instead of the producing sand face. I have done a couple of inflow test/completion jobs in Nigeria. I will like to get more information with regards to the status of the field development.
Scott_McNeil
Consultant
SPREAD Associates
Total Posts: 140
Join Date: 05/03/08
Hi Johnson,

Might not be relevant, but it would be worth also checking on how old the charges were.

Some that have been sitting on the shelf for a long time can loose their effectiveness, so you might not be getting as much of a bang as you think.

All the best

Scott McNeil
JimCarr
Retired
SPREAD Associates
Total Posts: 9
Join Date: 27/08/09
Hi Johnson,

Yes, I've just had this happen to us.
We perforated a 12m interval and then went straight to an injectivity test.
Couldn't get any injectivity and were considering re-perforating.
Decided to under-balance the well and flow back.
This was successful in cleaning up the perforations.
The injectivity test was repeated successfully and we didn't need to re-perforate.
The bottom-line is that perforation debris was totally blocking well-bore communication with the reservoir.
Hop this helps.
admin
Managing Director (rp-squared.com)
Relentless Pursuit Of Perfection Ltd.
Total Posts: 449
Join Date: 10/01/05
Hi Johnson

My first suggestions / questions would be:

1.  Double (then triple) check the correlation used for perforating - did the guns fire on depth?
2.  What static under-balance did you apply?
3.  Have you tried to flow the well? If not, why not?
4.  What fluid was adjacent to the perforations when you fired the guns? Type, composition (any additives)
5.  What is the drawdown you are applying (compared to pore pressure)?
6.  Is this an exploration or development well? i.e. how sure are you that the interval you have perforated is CAPABLE of unassisted flow?
7.  If a development well, how much depletion have your experienced/recorded?
8.  Whilst drilling (and completing) the well, were there any "events" that could indicate the formation has been impaired?
9.  How does what you have done/experienced compare with observations/actual events at offset wells?

I am sure that our esteemed membership could possibly add to this, but spending time and effort on addressing the above is a simple desktop exercise that is far cheaper than dashing into a second perforating run.

I hope this helps

Dave
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