Successful Execution of First Coiled Tubing "Shoot and Pull" Underbalance Perforation in Pakistan

Abstract

Over the past 80 years, various perforation systems have been developed to cover wide range of perforation applications and demanding reservoir conditions. Clean and effective underbalance perforations have a direct influence on reservoir performance. New perforation technologies and conveyance methods have developed, including Coiled tubing CT perforation. OMV had a requirement to perform additional perforations on one of their land wells, which was producing from a depleted zone. Well head shut in pressure had dropped down from an initial pressure of 3000psi to 1400psi. Pressure of zone of interest was in a range of 4700psi, which entailed that an underbalance at time of perforation would be more than 2700 psi. With such a high value of static underbalance, conventional wireline perforation application had its limitation and CT perforation seemed to be an ideal solution. OMV and Schlumberger experts collaborated to execute the high underbalance perforation with CT as the conveyance method. This required meticulous job design and planning as well as fabrication of a customized platform to safely run and retrieve guns in live well before and after perforations. Schlumberger CT firing head with 2.88" high shot density guns were used to perforate the zone of interest with a high underbalance of over 2500 psi. This marked successful execution of first CT shoot and pull perforation job in Pakistan where perforation guns were successfully conveyed and pulled to surface without killing the well, followed by well cleanup and testing. Post perforation results were very encouraging as OMV observed significant production increase where all objectives were met with no HSE/SQ incident.