Improving our understanding of fluid transport in rocks – CO2 sequestration Tim Senden Department of Applied Mathematics Research School of Physics and Engineering
Introduction • Underground storage of CO2 has been proposed as a means of mitigating climate change through ghg emissions. • Several major challenges to address • Volume of CO2 that can be stored within a given geological formation • Proximity to CO2 source (powerplant, gas field) • Long term storage security (e.g. leakage rate must be less than 0.01% per year)
CO2-rock interactions are a source of uncertainty in assessment of CO2 storage viability • Change injectivity (porosity, permeability etc) • May alter seal rock integrity • Mineral trapping / contaminant liberation … but supercritical CO2 is an unusual beast!! • Facts: Above 31°C and 73 atm (not uncommon in reservoirs/aquifers); • ½ as dense as water, and 1/10th as viscous but flows like a liquid. • while it does not mix with water is does react to make the water acidic • it dissolves in hydrocarbons.
Saline aquifer • Sleipner (Norway) • Globally ubiquitous • Need to ensure security to avoid groundwater contamination (true for any lithology) • Mineral trapping small volumetrically but potentially important (changes to flow properties) So how to study this troublesome fluid in microscopic pores within rock? Image source: Statoil
The X-ray micro-Tomography Facility Micro-focus X-ray source Rock specimen Double helical trajectory means very high fidelity data from micron to centimeter scale
We must manage our hydrocarbon resources efficiently Physical Parameters Reservoir Descriptors Electrical Conductivity Oil Saturation Dielectric Permittivity Water Saturation Neutron Gas Saturation Borehole Pressure Porosity Sound Velocity Permeability NMR Response Gamma-ray x-section Capillary Pressure Instead of a single data point we can extract 100’s from a single core How does fluid permeability correlate to other observables ?
Simulation Experiment • Triaxial cell • 8 – 25 mm cores • Beryllium cell • Axial strain < 1000 atm • Confining pressure < 100 atm • No creep over 8 hr • Designed for scCO2 • at present using analogue fluids
Mardie Green Sand – Barrow Is, WA Native state After exposure to CO2 equivalent Using analogue fluids Courtesy of Rowan Romeyn (Hons. student).
Since 2000 • Christoph Arns ** • Tomaso Aste • Holger Averdunk • Gareth Crook • Andrew Fogden • Abid Ghous • Stephen Hyde • Anthony Jones • Alexandre Kabla • Andrew Kingston • Munish Kumar • Mark Knackstedt • Shane Latham • Evgenia Lebedeva • Ajay Limaye * • Jill Middleton • Glenn Myers • Val Pinczewski ** • Vanessa Robins • Rowan Romeyn • Mohammad Sadaatfar • Arthur Sakellariou • Tim Sawkins • Adrian Sheppard • Rob Sok • Michael Turner • Trond Varslot • Paul Veldkamp * VizLab ANUSF ** UNSW Since 2006 The Digicore Consortium has included; Saudi Aramco, ExxonMobil, Shell, Chevron, BP, Total, Schlumberger, Baker Hughes, Abu Dhabi Onshore, Maersk, Petronas, PetroBras, Japan Oil & Gas, ONGC (India), BHP, BG, Conoco Philips, FEI, Digitalcore Since 2009 ANU/UNSW spin-off
Australian National Low Emissions Coal Research and Development(ANLEC) 2011 In partnership with Digitalcore and ANU received a multi-million dollar grant to develop methods to investigate CO2 – rock interactions in Australian aquifers. 3 years. Building an open access data repository, visualisation and simulation platform for tomographic data