The Impact of H2S in Repurposing Carbon Steel Pipelines for CO2 Transmission

Abstract Carbon capture and sequestration (CCS) and carbon capture utilization and storage (CCUS) projects continue to develop rapidly, and repurposing existing pipelines is an economically attractive option over the construction of a new pipeline. However, the transmission of gaseous and supercritical CO2 requires special design considerations rarely included in the original pipeline design. In addition to issues associated with incomplete records and overall pipeline integrity, internal scales from previous service can interact with certain CO2 streams to create corrosive conditions. This paper explores considerations for two scenarios: a pipeline that had not previously been exposed to H2S repurposed for a stream of CO2 now containing H2S and a pipeline that had been previously exposed to H2S repurposed for use with a clean CO2 stream without H2S. For the former case, this paper explores the specific impact of H2S within CO2 streams, which requires definition of the CO2 stream composition with respect to H2S concentration as well as other impurities. For the latter case, this paper explores how the initial design and prior H2S service may have affected a pipeline and how new CO2 service could be impacted.