Hello, we are about to perforate a sandstone reservoir around 5000ft deep. However the hole condition is not good therefore perforating efficiency is questionable. What do you recommend as actions to ensure maximum efficiency from these perforation?
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Dear Ahmed,
Many thank for posting your question. The problem you have stated is a very common issue faced in well engineering. More than often bad drilling & cementing practices lead to enlarged wellbores that cause perforation efficiency to reduce significantly. Fortunately, we can mitigate this problem through multiple techniques:
1. Use a deep penetrating gun. Perforating guns are designed either to penetrate deep into the formation or make large entrance holes. Choosing the right gun may considerably increase your perforation efficiency
2. Conduct Perforation gun efficiency analysis specifically for your formation/rock characteristics. This simulation will help you select the most appropriate gun. ProPetra have developed a unique perforation efficiency tool called PerfECT which you can review. It free to use. Other service providers also offer perforation gun comparison and analysis. Schlumberger calls their tool SPAN.
3. Use abrasive jetting perforations, a new technique of perforation that utilizes high stream of fluid with sand to create holes in wellbore and cement. Penetrations achieved through this technique is significantly higher.
4. You may consider conducting a small frac treatment such as a skin frac. Although not exactly designed for this kind of appilcation, a frac can provide excellent communication between wellbore & formation.
I hope this provides some options and clarity to your question. Feel free to let us know if you need more support.
Thank you,
Imran