CCUS Technology Gap: Review of Existing Methods for Chemical Control

Abstract Early CO2 flood systems were initially built using corrosion resistant alloys (CRAs). Operators and chemical companies had success switching downhole tubulars to carbon steel in the 1980s using chemical inhibitors. These CO2 flood systems are very different from carbon capture, utilization, and storage (CCUS) due to the high-water content which allows for near homogeneous distribution of the film-forming CIs. Scavengers have been used to remove hydrogen sulfide from carbon dioxide used for tertiary oil recovery. While some inhibitors have been developed and patented for combustion gas or high CO2 content not all are for scCO2, and none exist for controlling NOx and SOx. The corrosion challenges with CCUS are due to even smaller amounts of water contamination (1000s of ppm) as well as of small amounts of NOx and SOx (1000s of ppm) which are extremely aggressive in supercritical CO2 conditions with low water content. Impurities such as H2O, CO2, O2, H2S, NO2 can form strong acids or deposit sulfur that can greatly impact pipeline integrity. In this paper existing methods of chemical control will be reviewed with the view of developing chemical methods for controlling the challenges of CCUS asset integrity.