Geochemistry of storing CO 2 and NO x in the deep Precipice Sandstone

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1 Geochemistry of storing CO 2 and NO x in the deep Precipice Sandstone Sid Fe Mn K Qz J.K Pearce a G.K.W. Dawson a, S.D. Golding a, D. Kirste b, J. Underschultz a a University of Queensland, Australia b Simon Fraser University, Canada

2 UQ-Surat Deep Aquifer Appraisal Project (UQ-SDAAP) Acknowledgement The UQ-Surat Deep Aquifer Appraisal Project (UQ-SDAAP) is forecasted to run until end April 2019 within total current budget limit of up to AUD$8.1 million. The project is currently funded by the Australian Government, through the CCS RD&D programme, by ACA Low Emissions Technology (ACALET) and by The University of Queensland. We also acknowledge assistance from all group members of the UQ-SDAAP project, and also M. Grigorescu, S. Farquhar, A. Golab, J. Esterle and group, ANLEC R&D and CTSCo Pty Ltd for assisted access to open data sets. Disclaimer The information, opinions and views expressed here do not necessarily represent those of The University of Queensland, the Australian Government or ACALET. Researchers within or working with the UQ-SDAAP are bound by the same policies and procedures as other researchers within The University of Queensland, which are designed to ensure the integrity of research. The Australian Code for the Responsible Conduct of Research outlines expectations and responsibilities of researchers to further ensure independent and rigorous investigations.

3 Feasibility of large scale CO 2 geological storage, Surat Basin Overall project involves various aspects will only be discussing reactive geochemistry Evaluating the future option of injecting CO 2 in the Lower Precipice Sandstone At reservoir P ~ bar, T ~ C, CO 2 becomes a dense supercritical fluid, dissolves in formation water Majority of aquifer storage worldwide usually deep saline aquifers, however in this case - fresh to brackish CO 2 can be contained by - physical trapping (cap-rock e.g. clay rich shale/mudstone), residual trapping (rock pores) Chemical trapping (dissolution / ionic pair stabilisation), Solubility trapping, mineral trapping: precipitation carbonates CaCO 3 (calcite), FeCO 3 (siderite), etc...

4 Potential geochemical effects CO 2 dissolution in formation water - carbonic acid lowers ph dissolution minerals CO 2 + H 2 O H 2 CO 3 HCO 3- + H + Mineral dissolution divalent cations into solution Potential mineral trapping of CO 2 Precipitation other minerals (scales, clogging?) Potential changes to porosity / permeability? Potential changes to water quality?

5 CO 2 Impurities CO 2 streams may have low concentrations of impurites including SO 2, O 2, NOx, SO 3, H 2 S, H 2 O, CO, N 2, Ar, CH 4 etc. Low S content in most of Australia s coal, power generators had not been previously required to install Flue Gas Desulphurisation (FGD)or DeNOx Post combustion capture retrofits on existing coal plants need SO 2 scrubbers, NOx, Storing impure CO 2 may reduce capture and separation costs (Eliminating the SO 2 scrubbers in a CCS retrofit suggested to result in a 13% reduction in capital costs and 8% reduction in annual operating expenses Glezakou 2012) Impurity gases e.g. NOx, SOx, O 2 dissolve in formation water Form stronger nitric, sulphuric acids or oxidise, may be more reactive to minerals 4SO 2 + 2H 2 O 3H 2 SO 4 + H 2 S General published possible O 2, SOx and NOx content of capture streams (between a trace and 6% of the remaining composition is Ar or N 2 ) * Total SO 2 +SO 3, Δ EOR ppm as there is a lack of experiments on effects of O 2. Component Post combustion Oxyfuel DYNAMIS Comp. 1 Comp. 2 Comp. 3 Comp. 1 Comp. 2 Comp. 3 CO 2 (vol%) >95.5 O 2 (vol%) <4 Δ H 2 O ppm NO X ppm SO 2 ppm 10* 10* 20* * SO 3 ppm (Kather 2009),(IEAGHG 2011), (devisser 2008), ( Cottrel et al and Notz et al 2010), (Glezakou 2012)

6 Surat Basin, QLD Lower Precipice Sandstone reservoir Upper Precipice Sandstone and Evergreen Formation seal Westgrove Ironstone Member regional seal? Northern area More data / wells Very Low salinity Water bores Westgrove Ironstone Boxvale Sandstone Deeper central basin Less data/wells Brackish formation water?

7 Example Mineral Contents 898 m 1049 m 1082 m 1115 m 1138 m Lower Precipice SS Qz rich Upper Precipice SS includes clay rich and carbonate sections Evergreen Fm interbedded shales, sandstones, mudstones Westgrove Ironstone - siderite/chlorite 1169 m 1205 m 1154 m West Wandoan m Chinchilla m Condabri 1513 m Cabawin m Roma m

8 Porosity Examples (Chinchilla 4) Open porosity in Lower Precipice Sandstone, also in interbedded sections of Evergreen Formation and Hutton Sandstone Mudstone/shales slit sized porosity in clays (consistent with illite) Pore filling carbonates mudstone Pore throats sandstone Example QEMSCAN Evergreen Formation, Precipice Sandstone and µct (West Wandoan 1 well) Modified from Pearce et al., 2016

9 Example SEM-EDS (Chinchilla 4) m Poorly sorted Precipice Sandstone with kaolinite Lithology/mineralogy variable in upper Precipice and Evergreen Formation Fe-rich chlorite, plagioclase, K-feldspar Fe-Mg siderite, or Fe siderite in cemented zones +- Mn 1082 m 1017 m Sid Fe 992 m org Mn K chl

10 Lower Precipice Upper Precipice Evergreen Fm Evergreen Fm calcite CO 2 Evergreen Fm Lower Precipice +CO 2 NOx Pore filling clay Traces of Ti-oxide, Fe-oxide, pyrite, sphalerite, coal etc. Calcite cemented zones Previous experiments with CO 2 +/- SO 2, NO, O 2 carbonate cements dissolve, precipitation Feoxides, smectite, gypsum, barite etc.

11 Deeper Basin - Cabawin 1 well Deeper basin Burunga- Leichardt area Minerals vs analysed core depths Upper Precipice /Evergreen Fm clay rich +/- feldspar, siderite cements, calcite Lower Precipice Sandstone quartz rich Created from Grigorescu 2011

12 Kinetic geochemical modelling Kinetic geochemical modelling (GWB) CO 2 +/- SO 2 or NOx and formation water Reservoir conditions Minerals from core characterisation Use correct mineral compositions e.g. Fe rich chlorite where possible SEM-EDS information on minor minerals, composition, porosity, modifying reactive surface areas to supplement existing data Parameters based on Palandri and Kharaka 2004, White 1995 etc. Previous experiment model validation modify reactive surface areas (See e.g. Pearce et al. Chem. Geol. 2015, Farquhar et al., 2015, Kirste et al. 2017).

13 Precipice Sandstone m (Cabawin 1) precipitation Predicted change in minerals Predicted ph dissolution Quartz rich sandstone Low reactivity - slight dissolution mainly siderite, chlorite and albite. Precipitation of trace amounts of siderite and kaolinite. Overall no predicted change in porosity Formation of carbonic acid decreased ph, increased (buffered) slightly to 4.46 after 30 yrs.

14 Siderite cemented m (Cabawin 1) Siderite cemented m Lowered ph was buffered more strongly by siderite dissolution increasing gradually to 4.85 after 30 years precipitation of Fe or Fe-Mg siderite, with precipitation of kaolinite and also smectite clay (beidellite) predicted.

15 Evergreen Formation m (Cabawin 1) Contained 1% siderite and 0.7% calcite, relatively high albite content ~11%. More reactive - ph quickly buffered by dissolution of calcite to 4.96 after 30 years. Siderite dissolved and re-precipitated, smectite clay (beidellite and nontronite), ankerite/ferroan dolomite (mineral trapping) and kaolinite predicted to precipitate

16 Precipice Sandstone m with 30 or 100 ppm NO in CO 2 CO 2 streams may contain impurities including SOx, NOx etc. e.g. from coal combustion Depend on source and capture/purification process SOx, NOx, O 2 reactive to rock Addition of low concentrations NO in models precipitation of kaolinite, smectite, siderite e.g. Cabawin m - addition 30ppm NO 35% less siderite precipitation 100 ppm NO - 98% less siderite, ph not affected after 30 yrs Previous experiments with NO resulted in precipitation Fe(hydr)oxides and possible Fe-clays or amorph. material

17 Precipice Sandstone m with 30 or 100 ppm SO 2 in CO 2 30 ppm SO 2 5% more siderite precipitation (more chlorite dissolution), additional pyrite precipitation 100 ppm SO 2 3% less siderite precipitation, ph slightly lower 4.39 (vs 4.46) m 30 ppm SO 2 also slightly more chlorite dissolution and siderite precipitation (mineral trapping) than pure CO 2 case. For 1915 m mineral trapping and ph same as pure CO 2 case, additional pyrite precipitation Predicted porosity change negligible <0.05 % over 30 years Previous experimental data (West Wandoan 1 core) supports predicted ph effects

18 Sanity checks! Natural analogues and experiments etc m 1032 m (ironstone) Ladbroke Grove (modified from Watson et al., 2004) CO 2 -water-core experiments: Dissolved Fe Mineral precipitation input data limited compare model outputs to observations Comparison to natural observations and experimental/field site data Surat Basin and International Evidence of previous CO 2 alteration in the Surat Basin e.g. calcite fills (Golding et al., 2016), several generations siderite around chlorite cores (ironstone) (Farquhar et al., 2016), observations K-feldspar to kaolinite alteration Plagioclase conversion to ankerite in Ladbroke Grove, Vic, (Watson et al., 2004), several international sites Experimental data (Pearce and Golding et al.) for geochemical reactivity of core from several wells CO 2 +/- SO 2, NO, O 2

19 Conclusions and Future work For Quartz rich Lower Precipice Sandstone braided facies - predict low reactivity and low likelihood of plugging by precipitation Upper Precipice or Evergreen Formation predicted precipitation of siderite, ankerite, kaolinite +/- smectite, chalcedony, even trace amounts of calcite can quickly buffer ph Presence of ppm SO 2 in CO 2 - affect on ph, ppm NOx decrease in siderite precipitation More data needed in central Surat basin. Especially for presence of trace amounts of calcite, siderite, pyrite etc. Evidence for natural CO 2 alteration in the Surat Basin - can be used to constrain geochemical models Reasonable outputs compared with CO 2 natural analogues however more data from natural analogues needed (e.g. minerals precipitated, changes to porosity and permeability, metal and CO 2 sequestration) More data needed on metal content of cores / potential changes to reservoir temperature (field data)

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21 Previous experimental water chemistry data CO 2 -water-core Dissolved ions during reaction of Precipice Sandstone, Evergreen Formation, Hutton Sandstone Ca from calcite cemented core Si from cap-rocks with reactive silicate minerals Fe leaches from chlorite S from trace sulphides Use to test and validate geochemical models and reactive surface areas Created from Farquhar and Pearce et al., 2015