Demonstration of Flow Assurance for CO₂ Transport Operations

Background and project purpose?
This project aims to provide technology development and demonstration to improve large-scale CO₂ transport and injection. The project will reduce the uncertainty for operations, flow assurance, and improve Health, Safety and Environment (HSE). The experimental results will be used to verify and benchmark simulation tools and models and, where possible, published.

What was the project objective?
The DeFACTO Project has four main objectives:
• Develop a design basis for CO₂ transport and its interfaces based on demonstration and experiments including:
o Design and construction of vertical demonstration well for transient flows of CO₂-mixtures
o Operation and improvement of existing horizontal CO₂ flow rig at SINTEF and originally owned and delivered by Equinor, for verification purposes
o Operation and improvement of heat transfer testing facility at SINTEF, originally owned and delivered by Equinor
• Increase the value of the experimental results through development, verification and benchmarking of numerical tools
• Seek opportunities for commercialization of the DeFACTO results within the partnership of the project or with other suppliers and operators
• Publish fundamental and commercially non-sensitive results for aiding general progress of CCS

What has the project done in terms of activities?
The major activities in this project are:
• Engineering study on the vertical well flow loop and connection to existing horizontal loop delivered to SINTEF by Equinor
• Construction of the well flow loop and integration as well as control system development
• Commissioning of the integrated DeFACTO CO₂ facility
• Experimental study within some selected topics

The DeFACTO facility is a vertical flow facility that enables the circulation of CO₂ through a 90 meters deep U-tube loop built by SINTEF Energy Research in Gløshaugen (Trondheim). The project team overcame many difficult technical challenges in completing this integrated facility modification project, this led to significant delays and cost overruns.

The following experiments with pure CO₂ fluid have been carried out within the DeFACTO project:
• Convective heat transfer of single-phase CO₂ flow in a pipe: heat transfer coefficient is estimated.
• Phase change process in a well: CO₂ condensation process in a downward pipe flow.
• Transient operations: shut-in and depressurisations

The experimental results (data and physical observations) have been quality-assured and documented. The results will be used to improve understanding of corresponding physical phenomena in CO₂ transport and injection system, and used along with a wide variety of other data for validation of flow assurance tools in the future.

What has the project achieved? Did the project achieve its objective?
The main objective of this project was to reproduce different operational scenarios of a real CO₂ transport and injection system in a laboratory facility. The DeFACTO facility can be used for experimental studies with CO₂ fluid with and without impurities (N2 up to 20% CH4) in a pipe of 16 and 32 mm ID. Experimental studies that can be carried out with this facility are: single and two-phase flow in pipeline and well, heat transfer, phase change, fluid hammering, depressurization, leakage and various transient operations for pipeline and injection.

The vertical flow facility was constructed and integrated into the horizontal loop delivered by Equinor. Selected tests with pure CO₂ have been carried out. The obtained experimental data will provide relevant knowledge on CO₂ behaviour in an injection well. The data will help to develop, validate and benchmark numerical tools. Additional efforts (not covered in the current project) are needed to digest the experimental results received so far.

Future plans?
The experimental results need further detailed analysis, once this is done some results can be disseminated in conferences or journals. The DeFACTO facility has already been utilised in a research project (SIGNIFY) and is also involved in several ACT proposals. In addition, SINTEF is planning to propose extended experimental campaigns in future industry CLIMIT Demo projects, as well as via other channels such as national and EU research programs.