Technology readiness assessment of ultra-deep salt caverns for carbon capture and storage in Brazil

Abstract

This article presents a Technology Readiness Assessment (TRA) of a new concept called the Salt Cavern Hybrid Subsea Carbon Capture and Storage (CCS) System, which performs all the offshore natural gas and CO2 separation process with subsequent storage in offshore underground salt caverns. Currently there is a demand for CCS of large quantities of CO2 associated with CH4 in the pre-salt offshore oil fields in Brazil. The pre-salt reservoirs have as caprock 2000 m of continuous rock salt. This hybrid system is expected to perform, at the same time, the separation between the natural gas and CO2, and Carbon Capture and Storage of CO2, allowing the monetization of the separated natural gas. The Technology Readiness Levels (TRL) approach is discussed in this paper for estimating the maturity of the CCS System. The TRL analysis concluded that no technological gaps were identified that would made the project unfeasible and the TRL level enables the project to advance to the field test stage within a reasonably short time horizon. Once implemented it could be one of the largest CCS projects in the world. Also, this paper describes the conceptual design of this hybrid system and presents the results of a TRA showing the methodology that was employed in the process, the technology critical items that were analyzed and the results obtained for each of them and the design of a salt cavern for the storage of 1 billion Sm3 (Standard cubic meter) of a natural gas stream with high CO2 content.