help in wonderful results of acidizing!

**mohsen2396** · 06-12-2011, 01:56 PM

Dear guys please help me

There is one well which its water cut increases after carbonate matrix acidizing. before acidizing its drawdown was 600 psi with low permeability(2.6 md), high drawdown (600 psi) and a negative skin. Distance to water is 120 m. After acidizing the water cut increases from zero to 10 percent!! drawdown decreases to 300psi . So, How the water cut increases? (in acidizing we use 15 and 28% HCL with benzoic acid as divertor )

**ELgharib** · 06-13-2011, 09:56 PM

First, I assume the actual BSW you have is correct since you may have quality checked to make sure you really observe an increase in BSW.
Second, How long did you measure your water cut before the acid job? one, two or three months before? May be the well was producing a small water cut before the acid job.
Third, the acid will soak preferentially the water layer=> probably during the acid job a water prone layer helped to establish the commucation and propagate towards the water prone zone.
Last, make sure you are not back-flowing the water you pumped into the well during the acid job.

**Yengineer** · 06-13-2011, 10:49 PM

Yep, difficult to believe that the acid might have reached the water bearing zone 150m away. Have you got all the spend acid back? In adition to ELgharib I would say: What about cementing? can it be that hydraulic isolation was not so good and the acid might have damaged it further, creating communication with a water bearing zone.

**mohsen2396** · 06-14-2011, 07:52 AM

Dear Guys, Thanks for your reply

The last measured water cut in this well was one month before acidizing which was 0.5% ! At now one month elapses from acidizing. So I think all the spent acid came back. I said The distance to water is 120 m. but It's not really believable. It is maybe incorrect. Because there is no any other reason for water cut increase! Is there any other reason guys?

**ELgharib** · 06-16-2011, 10:36 PM

Your water leg could be at 120m, but the water production was trigerred by a fracture you cleaned with acid during ur job!!! I would suggest you observe for some time the production, how the WOR behaviour when you shut the well in or choke back will help you to understand if the water is coming from an underlying or overlying water layer !!! By the way carbonates reservoir usually exhibit fractures!

**Lawrencee** · 06-17-2011, 07:05 AM

i am lucky to see such professional things here.

**mohsen1919** · 06-17-2011, 08:46 AM

Thank you Elgharib and Yengineer

You are very professional in your field. but I have less than 1 year experience. So please explain in detail. you said what should we do? how we can realize the source of this water?from fracture or underlying/overlying water layer? At now the well is closed. so how we can observe the WOR behavior? How we can detect the fracture?