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?
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.
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