TABLE OF CONTENTS As discussed in the previous chapter, there are a limited number of reasons why sandstone acidizing treatments do not succeed. Understanding this is the first step in overcoming the perception that risk taking and frequent failure are inherent in sandstone acidizing. Such an understanding is also needed to recognize the exciting prospects of acidizing. To make the most of acidizing, treatment design must be approached as a process, rather than as an afterthought or as a last resort, as it often is.
The general approach to sandstone acidizing and to all acidizing treatments is as follows:
Select an appropriate candidate well for acid stimulation.
Design an effective treatment.
Monitor the treatment for subsequent improvement.
In selection of a candidate well, it is important first to analyze well performance and reservoir properties. In analysis of well performance and assessment of a well as an acidizing candidate, the following sequence of questions should be answered:
Is the well performing poorly?
If so, is poor reservoir quality the cause?
Or is formation damage the cause?
If so, what are the types of damage (damage contributors)?
What is the severity of the damage (skin)?
What is the location and depth of penetration of the damage?
Can acid remove the damage?
If so, what type of acid will remove the damage?
Will the formation be compatible with this acid?
If not, what alternative, non-acid treatment might remove the damage?
Well performance is largely dependent on reservoir quality and the nature of the formation matrix, as well...
