Call 2 – Storage

For a wide adoption of the Carbon Capture and Storage (CCS) technology, it is essential to provide a commercial operator with a reassurance of the predictability of their proposed site for CO₂ storage through geochemical monitoring techniques. This is particular important for assessing residual and solubility trapping, which are more secure than structural trapping of free-phase CO₂. It is difficult to quantify how much CO₂ is stored by residual and solubility trapping across an entire storage site. Hence, there is a need to develop a test which can be performed at a single injection well during assessment of a potential site for CO₂ injection. CO₂CRC, one of the world-leading CCS research organisations, conducted the Otway Stage 2B Extension residual saturation test in December 2014 to determine residual trapping at their Otway test site in Victoria, Australia, using a single-well field setting. In direct collaboration with CO₂CRC and other global research institutions (CSIRO Energy, University of Melbourne, Simon Fraser University, Lawrence Berkeley National Laboratory), we use water and gas geochemistry to establish the fate of CO₂ injected into the Paaratte Formation at the Otway test site. More specifically, we study the application of oxygen isotopes and noble gases to reconstruct levels of residual trapping of CO₂.

Main project funder category: UKCCSRC – Call 2
Funder name: UKCCSRC
Project date: Mar 2019
Lead institution: University of Edinburgh
Principal investigator(s): S. Gilfillan
Co-Investigator(s): G. Johnson, S. Haszeldine
Category: Storage/Monitoring
Primary research theme: CO₂ Tracers

We combine pore scale digital rock physics, reservoir condition special core analysis, and reservoir simulation to evaluate the performance of CO₂ storage for the major target storage regions of the UK.

Key objectives:

• Develop a dataset of relative permeability and residual trapping for major storage targets in the UK (Fig. 1), obtained experimentally at reservoir conditions
• Identify the contribution of pore scale rock morphology to multiphase flow dynamics and dissolution trapping
• Use the data in reservoir simulations to update dynamic capacity estimation for UK reservoirs

Main project funder category: UKCCSRC – Call 2
Funder name: UKCCSRC
Project date: Mar 2019
Lead institution: Imperial College London
Principal investigator(s): S. Krevor
Co-Investigator(s): G.A. Williams, M.J. Blunt
Category: Storage/Appraisal & Site Evaluation
Primary research theme: Generic Techniques/Site Specific

Highly-depleted gas fields represent prime potential targets for large-scale storage of captured CO₂ emitted from industrial sources and fossil-fuel power plants. Given the potentially low reservoir pressures as well as the unique thermodynamic properties of CO₂, especially in the presence of the various stream impurities, the injection process presents significant safety and operational challenges.

In particular, the start-up injection leads to the following risks:

• blockage due to hydrate and ice formation following the contact of the cold CO₂ with the interstitial water around the wellbore;
• thermal stress shocking of the wellbore casing steel, leading to its fracture and ultimately escape of CO₂;
• over-pressurisation accompanied by CO₂ backflow into the injection system due to the violent evaporation of the superheated liquid CO₂ upon entry into the wellbore.

Aims and objectives

The aim of our work is two-fold:

• to develop a homogeneous relaxation flow model for the numerical simulation of the highly-transient phenomena taking place in wells accounting for variable cross-sectional area during the injection of CO₂. Mass, momentum, and energy conservation equations are considered in the tubing. Wall friction, gravitational force, and heat transfer between the fluid and the surrounding formation are also taken into account.
• to perform a sensitivity analysis using various injection rates and temperatures, in order to propose optimal transient-operation design and develop best-practice guidelines for the minimisation of the risk associated with start-up injection of CO₂ into highly-depleted gas fields.

Main project funder category: UKCCSRC – Call 2
Funder name: UKCCSRC
Project date: Mar 2019
Lead institution: University College London
Principal investigator(s): H. Mahgerefteh
Co-Investigator(s): S. Brown
Category: Storage
Primary research theme: Depleted fields