PERFORMANCE OF CORROSION INHIBITORS FOR ACIDIZING JOBS IN HORIZONTAL WELLS COMPLETED WITH CRA LABORATORY TESTS

摘要

The search for oil has driven companies to explore and produce reservoirs located in deep waters. Sometimes these reservoirs produce corrosive fluids that lead to the use of expensive alloys. The high production costs sometimes can be minimized with the use of Extended Reach Wells (ERW), horizontal wells and the proper selection of corrosion resistant alloys (CRA). Horizontal wells have been used to allow higher production rates. CRA's are used either because it is absolutely necessary due to the corrosive environment or just to guarantee a longer time between work-over if the production fluids show moderate or even low corrosiveness. The economics of these expensive wells require high production rates. Therefore, acid jobs are often applied to remove reservoir damages produced during drilling or completion operations. Acid jobs are very aggressive to the tubing and down-hole equipment, so corrosion inhibitors are always used. This paper describes laboratory tests performed to verify the effectiveness of some corrosion inhibitors suggested for use with mud-acids to be injected in horizontal wells equipped with CRA tubing. For the conditions tested, no corrosion inhibitor showed acceptable performance for all materials tested if HCl was used as the base for the mud-acid generation. Better results, however, were observed if the corrosion inhibitors were used to mitigate corrosion of mud-acids that were produced from organic acids.