Geochemistry of storing CO2 and NOx in the deep Precipice Sandstone

J.K Pearcea

G.K.W. Dawsona, S.D. Goldinga, D. Kirsteb, J. Underschultza

aUniversity of Queensland, AustraliabSimon Fraser University, Canada

Fe

Mn K

Sid

Qz

Acknowledgement

The UQ-Surat Deep Aquifer Appraisal Project (UQ-SDAAP) is forecasted to run until end April 2019 within totalcurrent 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 ofQueensland.

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 ofQueensland, the Australian Government or ACALET. Researchers within or working with the UQ-SDAAP are boundby the same policies and procedures as other researchers within The University of Queensland, which aredesigned to ensure the integrity of research. The Australian Code for the Responsible Conduct of Researchoutlines expectations and responsibilities of researchers to further ensure independent and rigorousinvestigations.

UQ-Surat Deep Aquifer Appraisal Project (UQ-SDAAP)

Feasibility of large scale CO2 geological storage, Surat Basin

• Overall project involves various aspects – will only be discussing reactive geochemistry

• Evaluating the future option of injecting CO2 in the Lower Precipice Sandstone

• At reservoir P ~ 100-200 bar, T ~ 50-80°C, CO2 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

• CO2 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 CaCO3 (calcite), FeCO3 (siderite), etc ...

• CO2 dissolution in formation water - carbonic acid – lowers pH – dissolution minerals

• CO2+ H2O↔ H2CO3 ↔ HCO3- + H+

• Mineral dissolution → divalent cations into solution

Potential mineral trapping of CO2

Precipitation other minerals (scales, clogging?)

Potential changes to porosity / permeability?

Potential changes to water quality?

Potential geochemical effects

(Kather 2009),(IEAGHG 2011), (deVisser 2008), ( Cottrel et al and Notz et al 2010), (Glezakou 2012)

Component Post combustion Oxyfuel DYNAMIS

Comp. 1 Comp. 2 Comp. 3 Comp. 1 Comp. 2 Comp. 3

CO2 (vol%) 99.93 99.92 99.81 85.00 98.00 99.94 >95.5

O2 (vol%) 0.02 0.02 0.03 4.70 0.67 0.01 <4 Δ

H2O ppm 100.00 100.00 600.00 100.00 100.00 100.00 500.00

NOX ppm 20.00 20.00 20.00 100.00 100.00 100.00 100.00

SO2 ppm 10* 10* 20* 50.00 50.00 50.00 100*

SO3 ppm 20.00 20.00 20.00

General published possible O2, SOx and NOx content of capture streams (between a trace and 6% of the remaining composition is Ar or N2)* Total SO2 +SO3, Δ EOR 100-1000 ppm as there is a lack of experiments on effects of O2.

• CO2 streams may have low concentrations of impurites including SO2, O2, NOx, SO3, H2S, H2O, CO, N2, Ar, CH4

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 SO2 scrubbers, NOx, • Storing impure CO2 may reduce capture and separation costs• (Eliminating the SO2 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, O2 dissolve in formation waterForm stronger nitric, sulphuric acids or oxidise, may be more reactive to minerals

4SO2 + 2H2O ↔ 3H2SO4 + H2S

CO2 Impurities

• 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

Deeper central basin• Less data/wells• Brackish formation water?

Boxvale SandstoneWestgrove Ironstone

Surat Basin, QLD

Example Mineral Contents

Chinchilla 4 1193 m

1169 m1205 m 1154 m

1138 m898 m 1115 m1082 m1049 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

Roma 8 1043.6 mCabawin 1 2062.6 mCondabri 1513 mWest Wandoan 1 1210 m

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

Example QEMSCAN Evergreen Formation, Precipice Sandstone and µCT (West Wandoan 1 well) Modified from Pearce et al., 2016

mudstone sandstone

Pore throats

1197.7 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

Example SEM-EDS (Chinchilla 4)

1082 m

chl

992 m

Sid

org

1017 m

Fe

Mn K

• Traces of Ti-oxide, Fe-oxide, pyrite, sphalerite, coal etc.• Calcite cemented zones• Previous experiments with CO2 +/- SO2, NO, O2 – carbonate cements dissolve, precipitation Fe-

oxides, smectite, gypsum, barite etc.

Pore filling clay

calciteCO2

Lower Precipice Upper Precipice Evergreen Fm

Evergreen Fm Lower Precipice +CO2NOx

Evergreen Fm

• Deeper basin Burunga-Leichardt area

• Upper Precipice /Evergreen Fm – clay rich +/- feldspar, siderite cements, calcite

• Lower Precipice Sandstone quartz rich

Deeper Basin - Cabawin 1 well

Created from Grigorescu 2011

Minerals vs analysed core depths

• Kinetic geochemical modelling (GWB)• CO2 +/- SO2 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).

Kinetic geochemical modelling

Precipice Sandstone 2062.6 m (Cabawin 1)

dissolution

precipitation

• 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.

Predicted change in minerals Predicted pH

Siderite cemented 2043.1 m (Cabawin 1)

• Siderite cemented 2043.1 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.

Evergreen Formation 1915.4 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

Precipice Sandstone 2062.6 m with 30 or 100 ppm NO in CO2

• CO2 streams may contain impurities including SOx, NOx etc. e.g. from coal combustion• Depend on source and capture/purification process – SOx, NOx, O2 reactive to rock

• Addition of low concentrations NO in models – precipitation of kaolinite, smectite, siderite• e.g. Cabawin 1 2062.6 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

• 30 ppm SO2 5% more siderite precipitation (more chlorite dissolution), additional pyrite precipitation• 100 ppm SO2 3% less siderite precipitation, pH slightly lower 4.39 (vs 4.46)• 2043.1 m 30 ppm SO2 – also slightly more chlorite dissolution and siderite precipitation (mineral trapping) than

pure CO2 case. For 1915 m mineral trapping and pH same as pure CO2 case, additional pyrite precipitation • Predicted porosity change negligible <0.05 % over 30 years• Previous experimental data (West Wandoan 1 core) supports predicted pH effects

Precipice Sandstone 2062.6 m with 30 or 100 ppm SO2 in CO2

Sanity checks! Natural analogues and experiments etc.

• 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 CO2 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 – CO2 +/- SO2, NO, O2

1082.39m 1032 m (ironstone)Ladbroke Grove(modified from Watson et al., 2004)

CO2 -water-core experiments:Dissolved Fe

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 30-100 ppm SO2 in CO2 - affect on pH, 30-100 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 CO2 alteration in the Surat Basin - can be used to constrain geochemical models

• Reasonable outputs compared with CO2 natural analogues however more data from natural analogues needed (e.g. minerals precipitated, changes to porosity and permeability, metal and CO2 sequestration)

• More data needed on metal content of cores / potential changes to reservoir temperature (field data)

Created from Farquhar and Pearce et al., 2015

Previous experimental water chemistry data CO2-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