Publications

XY-302 is an ESP well produced from limestone reservoir. In March 2018, this well was shut in for two weeks after rig job due to operational issue. Production welltest showed a significant decrement from 640 BLPD to 190 BLPD and Productivity index (PI) decreased from 4.1 bbls/psi to 0.29 bbls/psi with suspect severe formation damage due to unclean killing fluid. HCl acidizing is common practice at carbonate but with several challenges such as instant reaction, corrosion issue, iron precipitation and hazardous chemical handling issue. From the study, Chelating acid system was then selected due to several considerations such as no issue of face dissolution problem, deeper penetration due to slow reaction, downhole metal equipment friendly for long exposure time, less hazardous than HCl, and have fairly cost compare with HCl acidizing. First attempt was conducted on May 9th, 2018 with 3 ft matrix penetration with 200 pptg concentration of Chelating acid system, and then soaked at top of perforation for 24 hours. From this stimulation, production increased from 190 BLPD to 400 BLPD and PI increased from 0.29 bbls/psi to 1.3 bbls/psi. However the result was still below expectation. Second attempt was conducted on June 5th, 2018 with 5 ft matrix penetration with 200 pptg concentration of Chelating acidizing and soaked for 48 hours. The result is satisfying with 984 BLPD and WC 93%. PI increased from 1.3 bbls/psi to 3.68 bbls/psi. From this result, slow reaction in Chelating acid has advantage to form a deeper and sufficient wormhole to overcome the damage. It also supported by sufficient soaking time period from 24 hours to 48 hours. Chelating acidizing have no issue regarding ESP metal equipment even at long exposure soaking period. This Chelating acid system open a new way to overcome many challenges in the future acidizing treatment.