Study and Application of a Corrosion Inhibitor Used in Self-diverting Acid

Horizontal wells completed with screen pipes are generally acidized with diverting acids, a method with which acid can be evenly distributed in a target zone with ease and effectively. Corrosion inhibitors, an important insurance for safe operation of acidization with diverting acids, are not compatible with most of the self-diverting acids presently in use, therefore the diverting action is negatively affected, and the corrosion inhibitive efficiency is remarkably reduced. A self-diverting acid, ZXHS, has recently been developed aimed at addressing these problems. Laboratory evaluation showed that the corrosion rate of ZXHS can be controlled within 5 g/(m²ws) at 90℃, and within 20 g/(m²ws) at 120℃, all conforming to the industrial requirement of "Grade 1" product. A selfdiverting acid treated with ZXHS had viscosity of greater than 160 mPa·s, and good corrosion inhibition and diverting performancecan be achieved with the diverting acid. ZXHS has been used in Dagang oilfield and Al-Ahdab oilfield (Iraq), gaining good operation achievements.