Maximising the value of digital core analysis for carbon sequestration site assessment

Final Project Report

This report highlights the achievements of the project and illustrates results associated with each achievement in a summary form.

Sub Project 1: Final report of RCA and SCAL data on plugs from West Wandoan-1 Well

Site-specific full suite of properties and multiscale images of core material from the Evergreen Formation (seal) and Precipice Sandstone (reservoir). Imaging was performed in 3D by X-ray computed tomography (CT; whole core, core plug, sub-plug) and in 2D by Scanning Electron Microscopy (SEM; pore-scale). Digitally calculated comprehensive dataset at the pore and core plug scale.

Sub Project 2: Final Report on digital core analysis results from Surat Basin West Wandoan-1 Well (with Appendix A)

This work focussed on the use of high resolution 3D μCT images to digitally determine petrophysical properties including porosity, permeability, and mineral phase distributions for a series of reservoir and seal core samples from the CTSCo Wandoan project.

The QEMSCAN mineral analysis provided essential information to identify and quantify the minerals that are contributing to reservoir micro-porosity and also to understand the distribution of minerals that are reactive to CO₂.

Generally, the Precipice sandstone is highly porous and permeable and is therefore a good CO₂injection target, but some zones occur that have low porosity and permeability. The zones with low porosity and permeability should assist the security of the injection by acting as baffles to CO₂ migration.

Sub Project 2 – Appendix B

Sub Project 2 – Appendix C

Sub Project 2 – Appendix D

Sub Project 2: Database for Digital Core Analysis

This work focussed on providing a full internet access digital database with all conventional and digital core analysis data, user guide, and workshop on software for all users.

The Digital Database for Core Analysis (DDCA) represents a secure database that is able to store and present diverse data. It is built on a sophisticated back-end architecture. It will enable the data generated in this large project to deliver value to the end-users of the Surat basin flagship project. With the essential framework in place, the DDCA is at a point where a relatively small additional effort could yield major improvements in data presentation and the user-friendliness, pending sufficient user feedback.

Sub Project 3: Final Report on digitial core analysis and property correlations from in-situ studies using supercritical CO₂

Demonstrated site specific 3D imaging of in situ supercritical CO₂ saturation at the pore scale Conducted direct, 3D pore-scale imaging of supercritical CO₂ and brine within Surat Basin core material during CO₂ injection at aquifer pressure and temperature conditions, by microCT. Illustrated that capillary trapping is a significant mechanism for CO₂ storage in the Precipice Sandstone and likely to be stable over timescales of decades to centuries and that CO₂-brine displacement properties are typical of a strongly water-wet system.

Sub Project 4: Final report on correlation of image-based modelling to experimental flooding data

Developed robust flow simulators for CO₂-brine flooding A new, geometrically accurate pore-scale model for CO₂-brine flooding was developed. CO₂-brine relative permeability, saturation, and capillary pressure curves for different rock types were derived. Showed that DRT results are consistent with laboratory data from numerous labs (e.g., Stanford, Imperial College). Data sets allow identification of potential uncertainties associated with laboratory data (e.g. impact of wettability, initial water saturation).

Sub Project 5: Final report on geochemical reactivitiy studies of core material using ScCO₂ (with Appendix A)

Performed time-step 3D imaging before and after geochemical reaction with CO₂:brine Performed pore-scale 3D imaging before and after reaction of the reservoir, seal and over-lying formation. Pure CO₂ and mixed gas containing SO₂ and O₂ were tested. The images show some localised changes including the dissolution of some carbonate minerals, degradation of some minerals and precipitation of others.

Sub Project 5 – Appendix B

Sub Project 5 – Appendix C

Sub Project 5 – Appendix D

Sub Project 6: Integrate pore to plug to core to log upscaling methods for static and dynamic properties and report on upscaling for specified flow units at pore/core/log scales in the Surat Basin, report on integration/extrapolation of pore/core scale data to continuous logging measurement

Validated application of DRT to CO₂ reservoir and seal characterisation with comparison to laboratory and provided correlations to wireline log data Showed that DRT results are acquired in faster and at potentially reduced cost compared to traditional laboratory methods. Illustrated importance of rock heterogeneity at all scales to provide a quantitative bridge between plug measurements and log scale data.

Sub Project 7: Multi-scale reservoir characterisation – seven scales from pore to core to geocellular models.

This project delivers two auditable workflows to correctly and conveniently carry out the classification and upscaling processes:

• Component A: Methods to classify and upscale from pore to whole core
• Component B: Methods to classify and move from core plug and whole core to the geocellular dimensions.

The workflows are designed to upscale simple single-value rock properties, as well as saturation-dependent properties (complex properties that depend on the relative saturations of the fluids in the reservoir including CO₂).

The final products of this project are a module in FEI’s software to implement the pore to whole core workflow and a second module in the eGAMLS software, called the “Classification and Upscaling of Saturation-dependent Properties” (CUSP) module, to move data from core plugs through whole core to geocellular models. The CUSP module will be made available to the industry by standard commercial software licencing and will be of major importance to successful CO₂ sequestration modelling.