Quote Originally Posted by dipak_m View Post
Dear Yengineer and other members,
Thanks for you valuable responses. My reservoir is purely depletion drive reservoir, so pressure become low. Water injection started after 10 years of production but due to water injection not much pressure is jacked up. Clay is the main problem. Some wells HF was done but result is not encouriging. In some wells decline data is available.
First off - please ensure that your drop in productivity is not primarily attributed to simply drop in reservoir pressure

If your reduced Pr cannot be responsible for majority of your PI reduction, then next step is figuring out what is.

With water production, you often have migrating clays - what sorts of clays do you have?
Did you do water compatibility checks on your injected water? How have your injector pressures been trending?
Would simple reperforation with big charges benefit?
Have the PI's always been poor? (ie could your understanding of your KH simply be wrong)
If your PI's have changed, has it been gradual, or abrupt? Can you link it to (for example) water breakthrough?
Could it be rel perm behaviour as your watercuts have changed?

My take is that IF you have some migrating clay fines, and IF those clay fines can be partially dissolved and/or immobilized with clay/mud acid then you may have an application for acidizing in your case - but there are a lot of if's there. There are many causes of PI reduction for which acidizing will do nothing, and quite a few scenarios in which the wrong acid job will actually ruin your well.