Decarbonisation Technology - February 2025 Issue

Key elements of flow assurance in carbon capture and storage The challenges and strategies involved in optimising CO 2 flow for safe and effective storage

Abbey Grant Belltree Group

E merging technologies such as carbon capture and storage (CCS) are crucial for reducing and removing anthropogenic carbon dioxide (CO₂) emissions from the atmosphere. Since the Paris Agreement in 2015, countries worldwide have set targets to limit global average temperatures from reaching 1.5°C above pre-industrial levels. The urgency to meet these targets has driven the development of CCS projects from previous concepts of CCS, such as enhanced oil recovery (EOR), which began in the 1970s. There are now 50 commercial-scale CCS projects operational and 534 in development worldwide (Global CCS Institute, 2024) . Flow assurance plays a critical role in the CCS process, ensuring that CO₂ can be transported from its point of capture to its permanent storage site without disruptions. This involves maintaining CO₂ in its supercritical state during pipeline transport, managing pressure and temperature to prevent phase changes, and addressing potential risks like corrosion and blockages. New and developing CCS projects can anticipate and mitigate these challenges by making flow assurance a key factor in the successful deployment of CCS at scale, drawing on decades of experience with CCS in the oil and gas industry. Selecting the appropriate subsurface storage location is also a crucial component of any CCS project. Using data-driven tools such as bMark can allow screening of potential storage prospects to help identify the optimum storage site. This article explores the intricacies of flow assurance in CCS, highlighting the challenges

and strategies involved in optimising CO₂ flow for safe and effective storage. Supercritical CO₂ CO₂ can be transported in any form, but it is often compressed into a liquid because it occupies significantly less volume compared to its gaseous form. When transported via pipeline, it is most efficient for CO₂ to be in its supercritical state with pressures higher than 74 bar and temperatures higher than 31°C. This represents highest point in which it can exist as a vapour and liquid in equilibrium (TWI, 2010) . In this state, CO₂ has

Dense phase

Supercritical

Pipeline

73.8

Liquid

Critical point

Solid

5.18

Triple point

Gas

-56.6

30.98

Temperature (˚C)

Figure 1 Phase diagram of CO₂, showing the estimated areas of operation for transport via ship, truck, and pipeline Source: Simonsen et al., 2023