Remove debris from existing perforations in permeable rocks and increase productivity or injectivity.
Perforating an existing producer with a completion in place would typically be limited in terms of gun size and perforation cleanup ability, hence affecting the well performance. This paper is a case study of a through-tubing additional perforating job, its performance analysis, and finally the implementation of a wellbore implosion technique for perforation tunnels cleanup. Job design and the well performance analysis are also presented.
The zone selected for the initial additional perforation was analyzed and a gun system simulation was performed. After the initial perforating job, surface and downhole surveillance data were collected for perforation performance analysis. Based on this analysis, a wellbore implosion technique was selected for perforation tunnels cleanup to enhance their productivity. Several wellbore implosion job simulations were performed based on various design scenarios. The optimal design was selected and executed successfully. Postjob well performance was then analyzed and compared with earlier performance. Although this implosion technique cannot improve or alter the reservoir rock deliverability, its ability to perform perforation cleanup is expected to be evident from the well performance analysis.
Analysis of the well performance after initial perforations showed a lower productivity index (PI), which was expected considering that the perforating job was conducted through-tubing while the completion was in place. The subsequent well implosion technique was executed successfully, and after that operation, the PI of the well improved, indicating the success of the technique to clean the perforation tunnels.
Because many wells suffer from improper perforation cleanup, this case study provides an important example for such wells, whether old or new, to replicate and instantly enhance their productivity. This technique can also be implemented in injector wells to enhance their injectivity.