Tech Report

Novel scale dissolver removes calcium carbonate scale in deepwater well

Published: 10/13/2023

Plot of pH and calcium content shows effective noncorrosive dissolution by CAL-Acid scale dissolver.
SLB proposed CAL-Acid scale dissolver as a viable fast-acting, noncorrosive alternative to conventional mineral acid treatments of carbonate scales. After a stringent qualification covering corrosion measurements; crude, fluids, and material compatibility testing; and assessment of emulsion and asphaltene tendency, the operator approved a 50% CAL-Acid scale dissolver solution for the descaling operation. After three consecutive placements of 125 bbl of the 50% CAL-Acid scale dissolver solution, the carbonate scale blockage was successfully removed, as confirmed by a wireline inspection performed by the operator.
Location
Gulf of Mexico, United States, North America, Offshore
Details

Technology
CAL-Acid scale dissolver

Background

A customer operating one of the largest deepwater producing fields in the Gulf of Mexico was preparing for a significant intervention for water shutoff and asphaltene removal when CaCO3 scale was discovered just below the subsurface safety valve (SSSV). The scale blockage prevented the use of downhole tools to mitigate the effect of increased water production and sampling for assessing asphaltene onset conditions. Corrosion experts were against pumping HCl downhole to remove the scale because of corrosion concerns for the completion.

Products Used