Reservoir productivity restoration in dual-string completion well using perforation method

Abstract

A sudden drop of production rate can happened due to formation damage, mechanical failure and others unprecedented problems. Selecting the suitable well stimulation method to treat the unproductive reservoir or to restore the reservoir productivity for a dual-string completion well which have multiple production zones becomes a challenge as there is no direct access to the problem production zone to investigate the root cause of the problem. Conventional method such as acidizing and hydraulic fracturing not an option for this situation, therefore re-perforation the production zone method have been decided to restore back the reservoir productivity. The case study have showed that a deep penetrating charge perforating system is required for this perforation method as the perforation need to penetrate the blast joint, annulus material, casing, the formation damaged zone and the formation. Further perforation analysis has been done to analyze the perforation designs which produce optimum penetration. Several parameters that expected to affect the perforation performance have been selected to simulate the perforation process using SPAN software. The result shows that the formation rock strength have a significant impact to the penetration length. Meanwhile, annulus materials slightly affect the perforation performance. A detail design of perforation gun system properties such as standoff position, shot density and shot phasing able to produce an optimum performance as each parameters have its own impact to the perforation performance. Further study on the others option of remedial sand control for the unconsolidated formation and the integrity of the blast joint after perforation is recommended to improvise this method.