A Coupled Geomechanical, Acoustic, Transport and Sorption ... › sites › default › files › netl...A Coupled Geomechanical, Acoustic, Transport and Sorption Study of Caprock

A Coupled Geomechanical, Acoustic, Transport and Sorption Study of Caprock Integrity in

Carbon Dioxide (CO2) SequestrationProject Number: DE-FE-0023223

Manika Prasad, Colorado School of MinesCo-I: Bill Carey (LANL), Ronny Pini (Imperial College)

Post-Docs & Students: Nerine Joewondo,Kurt Livo, Manju Murugesu, Mathias Pohl

U.S. Department of EnergyNational Energy Technology Laboratory

Mastering the Subsurface Through Technology Innovation, Partnerships and Collaboration:Carbon Storage and Oil and Natural Gas Technologies Review Meeting

August 13-16, 2018

2

Presentation Outline• Objectives and motivation• Experimental Updates

1. Mineralogy Control on CO2 Accessibility on Micropores of Shales for CCUS Application

2. Acoustic Measurements with CO2 saturation3. NMR studies of CO2-saturated brine4. Direct-shear experiments on shale permeability

• Accomplishments to date• (Near-) Future work

Center for Rock Abuse

Objectives

• Determine the behavior of intact and fractured caprocks when exposed to supercritical CO2 at elevated pressures

• Quantify adsorption and acoustic properties of shales with sorbed CO2

• Provide framework for monitoring, verification and accounting (MVA) efforts of CO2sequestration and its effect on caprock

Center for Rock Abuse 3

(1) CO2 Accessibility in Shale Micropores

• Gas adsorption to characterize nanopores• Samples Used• Analysis methods and Results• Application to CO2 storage

4Center for Rock Abuse

Storage capacity estimates:– Economically feasible CO2 capacity of Utica +

Marcellus + Antrim + Devonian Ohio ≈ 50 Gt(Godec et al, 2014)

– Theoretical CO2 capacity of Utica = 10 Gt (Godec et al, 2014)

– 80% storage capacity by sorption (Ambrose et al, 2012)

Motivation

Center for Rock Abuse 5Joewondo and Prasad, 2018

P. Klobes and K. Meyer (BAM, Germany)nanopores

Typically, N2gas is used

Kinetic diameters: CO2 (0.33 nm) < N2 (0.36 nm). We use CO2 to access smaller micropores than those accessible to N2

Pore characterization methods


• Recommended practice (IUPAC 1985 & IUPAC 2015)• Adapted N2 adsorption to characterize shales, also compared

to WIP (Kuila, 2013)• Limited accessibility for N2 in immature oil window samples

due to blockage by bitumen (Saidian, 2015)• Limited pore accessibility dependent on mineralogy and gas

type; preferential CO2 uptake in OM (Kumar, 2016)• In presence of water, preferential uptake of CO2 only in OM

not in clay minerals (Kumar, 2016)• N2 - and CO2- derived PSD on shales with 2-21% TOC

Previous studies


• Standard clay samples – benchmarking – Illite, Illite-smectite, Na-rich montmorillonite

• Producing shales in North America– Bakken (7-21% TOC), Utica (2% TOC) and Niobrara (3-5% TOC)

• Analog to caprock of CO2 storage site in the Norwegian North Sea – Agardhfjellet (12% TOC), Rurikfjellet (2% TOC)– CCS candidates

Samples Used


• Require high pressure setup to measure full isotherm

• P0 > 1 atm

N2 at 77K CO2 at 273 K

• Diffusional limitations of N2molecules in narrow pores

• Underestimate micropores

Measured adsorption isotherm


Bakken

Niobrara

Utica

Agardhfjellet

Rurikfjellet

Note: Opposite trend of N2- and CO2- derived pore structures;Mudrocks with high TOC have higher CO2 storage potential

N2 CO2

TOC controls on micropore volume


Micropore volume measured in this workUtica = 2E-3 cc/g Agardhfjellet = 11E-3 cc/g

Assume micropores are filled with CO2CO2 density 0.6 g/cc (30 C, 8 Mpa) (van der Meer 2005)Shale density 2.4 g/cc

Calculated CO2 storage capacity in 1 m3 of shales from this workUtica (2% TOC): 2.8 kgCO2 Agardhfjellet (12 % TOC): 15.8 kgCO2

Compare with Godec et al. (2014) for the same area:Average thickness of 150 ft or 45.7 m (Refayee et al. 2016) Theoretical CO2 capacity of Utica formation

19.7 GtCO2 (this work) and 10 GtCO2 (Godec et al. 2014)

Implications for Storage Capacity


Comparing CO2 and N2- accessible volumes


0

0.002

0.004

0.006

0.008

0.01

0.012

0 5 10 15 20 25Diff

eren

ce in

mic

ropo

revo

l. (C

O2

-N2)

[cc/

g]

TOC from RockEval [wt. %]

Bakken

Utica

Niobrara

Svalbard

Excess CO2 storage depends on TOC

Joewondo and Prasad, 2018

Surface Area and Clay Content

13

• OM pores are hydrophobic• OM pore development starts at the onset of oil window• Presence of bitumen free OM pores• Cryogenic N2 blocked by nano-sized pores in organic matter

0 0.1 0.2 0.3 0.4 0.5Clay fractional weight

0

4

8

12

16

20

N2 B

ET S

SA (m

2/g)

114

11005

2

5 16

7219

3

13LG

1

44

TOC weight %0 (Siltstone)6 to 1313 to

Preferential sorption of fluids


Quantification of hydrophilic and hydrophobic pores of shales

Preferential sorption of fluids depends on polarity of surfaces

Kumar, 2016

Sorption in shales with water


‘dry’ Bakken

‘dry’ Illite

Illite + water

CO2 sorption at 50 °C

0 500 1000 1500 2000Pressure [psi]

0

1

2

3

4So

rptio

n E

xces

s [m

mol

/g]

Bakken + water

Kumar, 2016

Sorption in shales with water


Illite: Water Imbibed Bakken: Water Imbibed

CO2 sorption CO2 sorption

OM

In presence of water: Illite pores take up water; CO2 fills OM pores

Kumar, 2016

Environmental Scanning Electron Spectroscopy (ESEM)

Spot Analysis

12

3

4

5

6 Darker areas: clay- and OM-

richLighter areas:

silt- rich

Center for Rock Abuse 17Murugesu, 2018

Agardhfjellet from Svalbard

Sorption in Zeolite


Without vacuum, N2-uptake is 25% less than degassed sample

Joewondo and Pohl, 2018

Waveforms and Velocities with CO2


-600

-500

-400

-300

-200

-100

0

100

200

300

400

15 17 19 21 23 25 27 29

Am

plitu

de [m

V]

Time [µs]

Vacuum; Vp=823.5 m/s244 psi; Vp=852.0 m/s401 psi; Vp=859.3 m/s531psi; Vp=861.8 m/s

Sample was not oven dried/degassed

Pohl and Joewondo, 2018

Frequency and Velocities with CO2


0

10

20

30

40

50

60

0 200 400 600 800 1000

Am

plitu

de

Frequency [kHz]

Vacuum; Vp=823.5 m/s244 psi; Vp=852.0 m/s401 psi; Vp=859.3 m/s531psi; Vp=861.8 m/s

Sample was not oven dried/degassed

Pohl and Joewondo, 2018

Ultrasonic Velocities


3

4

5

6

0 1000 2000 3000 4000 5000

Vp

[km

/s]

Pressure [psi]

Dry Butane CO2

2

2.5

3

3.5

0 1000 2000 3000 4000 5000V

s [km

/s]

Pressure [psi]

Dry Butane CO2

Sharma, 2016

Carbonate core

Seismic Velocities


2.00

2.25

2.50

2.75

3.00

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50

Vs [

km/s

]

Log frequency [Hz]

DRY BUTANE CO2

Sharma, 2016

Carbonate core

• CO2-accessible micropore volume depends on TOC• Need to complement N2 measurements with CO2 for CO2 storage

capacity• CO2 storage capacity increases with TOC• CO2 storage capacity decreases in presence of water (clay

effect)

• Frequency content (seismic attenuation) is sensitive to gas content

• Fluid in micropores depends on mineralogy – should be accounted for in seismic inversion

Conclusions


Synergy Opportunities– Calibrate rock physics models with partial saturation due

to mineralogy – dependent pore volumes and preferential fluid sorptions. Relevance: 4D seismic operations

– Investigate well log NMR signals for changes in fluid signatures versus changes in the rock due to rock –fluid interactions. Relevance: CCUS and Oil & Gas operations

– Joint acoustic –permeability changes with CO2 before and after shearing. Relevance: caprock changes with stress changes

– Imaging CO2 migration – student intern with SINTEF24Center for Rock Abuse

A Coupled Geomechanical, Acoustic, Transport and Sorption Study of Caprock Integrity in Carbon Dioxide (CO2) Sequestration��Project Number: DE-FE-0023223Presentation OutlineObjectives(1) CO2 Accessibility in Shale MicroporesMotivationPore characterization methods Previous studiesSamples UsedMeasured adsorption isothermTOC controls on micropore volumeImplications for Storage CapacityComparing CO2 and N2- accessible volumesSurface Area and Clay ContentPreferential sorption of fluidsSorption in shales with waterSorption in shales with waterEnvironmental Scanning Electron Spectroscopy (ESEM)Sorption in Zeolite Waveforms and Velocities with CO2Frequency and Velocities with CO2Ultrasonic VelocitiesSeismic VelocitiesConclusionsSynergy Opportunities

A Coupled Geomechanical, Acoustic, Transport and Sorption ... › sites › default › files › netl...A Coupled Geomechanical, Acoustic, Transport and Sorption Study of Caprock

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