DEVELOPMENT OF A SYNERGISTIC BLEND OF CORROSION INHIBITORS FOR ACID CLEANING

Abstract

Mineral scale, such as calcite, can build up on the walls of
production wells when calcite inhibition is not used or is
poorly designed or managed. When this occurs, flow is
restricted leading to reduced efficiency or possibly complete
loss of production. Scaled wells can be cleaned using acids
such as hydrochloric acid. While acids are great for dissolving
scale, they are very aggressive to the underlying metal.
Corrosion inhibitors are used to prevent damage to the metal
during acid cleaning.
A synergistic blend of inhibitors was developed which
provide corrosion protection for well rejuvenation with
hydrochloric acid. Initial screening began with jar tests at 95
oC and 15% hydrochloric acid. The most promising
candidates were blended together and reevaluated. A
combination of inhibitors provided superior protection to the
individual inhibitors alone. Subsequent tests in 10% HCl at
150 oC showed that a formulation provided excellent
protection even at higher temperatures.