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Technical Paper: Determination of Load Effects on a Sealbore Packer with Floating Seal Assemblies During a Dynamic Underbalanced Perforation

Society: SPE
Paper Number: 185522
Presentation Date: 2017
 Download: Determination of Load Effects on a Sealbore Packer with Floating Seal Assemblies During a Dynamic Underbalanced Perforation (1.68 MB PDF) Login | Register

 

Abstract

Combining tubing-conveyed perforation techniques with completion isolation valves and sealbore packers enables multiple entries to the reservoir, with different production strings. It also avoids recurrent use of killing fluids because the packer and isolation valve mechanically protect the reservoir. The perforation technique also results in a dynamic underbalance, creating tunnels as clean as possible. However, it may generate a huge pressure differential between the upper packer annulus and the inner string below the packer, which causes the upper string to exert extra compressive force on the packer.

The presented workflow relies on new software solutions to ensure successful and safe operations. The dynamic underbalance perforation's effects are simulated in appropriate software, which are then integrated with tubing design analysis suites. The combination of both results provides a more conservative and complete methodology of possible events occurring in the completions, enabling the extent of the loads to be safely evaluated and specifically addressed. The analysis indicates possible job modification strategies, such as increase of packer to gun length, changing the perforation charges loading arrangement, modifying the production string seal length, or installation of a stiffer upper completion string.

For the present work, a study case was thoroughly explained, where excessive load of the packer could occur in result of the differential pressure across the elements and floating seal units. The above mentioned design changes are explored individually through the workflow and the results discussed. These changes can reduce the forces acting on the packer, prevent major mechanical failures, and ensure the job stays within operational limits.

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