Mudstone CO 2 sealing efficiency K. Kurtev, A. Aplin and S. Abrakasa University of Newcastle.

Mudstone CO2 sealing efficiency

K. Kurtev, A. Aplin and S. Abrakasa

University of Newcastle

Evidences for leakages in North Sea

SAMPLE αααC29S ααα29R (S/S+R)*100 20S/20R R₀ EQIVALENT (STERANE) αβC32S αβC32R (S/S+R)*100

4800 5770 11598 33.2220175 0.4975 0.573774789 178918 132230 57.50253898

7990 13834 29958 31.59024479 0.46178 0.556272114 22645 16792 57.4206963

8300 45731 98341 31.741768 0.46502 0.557862133 96402 71005 57.58540563

Phenantherene 1MP 9MP 2MP 3-MP MPI-1 R₀ EQIVALENT (MPI-1)

2172906 990083 1570448 1159589 1160506 0.735225271 0.841135162

667992 610481 643708 591061 424375 0.792409248 0.875445549

583565 423589 435310 395252 283191 0.705504262 0.823302557

Aliphatics (saturated)

Aromatics

High TOC due to asphaltenesTmax is low – no HC formation

32.00 34.00 36.00 38.00 40.00 42.00 44.00 46.00 48.000

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Ion 191.00 (190.70 to 191.70): SA8300LS.D

32.00 34.00 36.00 38.00 40.00 42.00 44.00 46.00 48.000

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Ion 191.00 (190.70 to 191.70): SA7990LS.D

32.00 34.00 36.00 38.00 40.00 42.00 44.00 46.00 48.000

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Ion 191.00 (190.70 to 191.70): SA4800L.D

27.00 28.00 29.00 30.00 31.00 32.00 33.00 34.00 35.00 36.00 37.00 38.00 39.000

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Abundance

Ion 217.00 (216.70 to 217.70): SA7990LS.D

27.00 28.00 29.00 30.00 31.00 32.00 33.00 34.00 35.00 36.00 37.00 38.00 39.000

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Ion 218.00 (217.70 to 218.70): SA7990LS.D

29.00 30.00 31.00 32.00 33.00 34.00 35.00 36.00 37.00 38.00 39.00 40.000

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Abundance

Ion 217.00 (216.70 to 217.70): SA4800L.D

29.00 30.00 31.00 32.00 33.00 34.00 35.00 36.00 37.00 38.00 39.00 40.00 41.000

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Abundance

Ion 217.00 (216.70 to 217.70): SA8300LS.D

29.00 30.00 31.00 32.00 33.00 34.00 35.00 36.00 37.00 38.00 39.00 40.00 41.000

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Ion 218.00 (217.70 to 218.70): SA8300LS.D

Modelling studies

Goals

1. To identify the key structural control factors in mudstones important for CO2 migration;

2. To recognize and formulate the basic types of heterogenity of those key flow control factors ( main mudstone texture types resulted from the different regimes of sedimentation & consolidation);

3. To define method(s) for parametrization of the the basic types of textural / structural connectivity responsible for CO2 leakage;

CO2 Leaking Systems

Leakage is a multiscale Flow Process in Clay-Rich Sediments

Sample scale Intermediate scale:log interval or

~ 1 m scale

Seismic scale

Leaking Elements:

- Pore network;- Grain Sizes;- Microfractures;

Leaking Elements:

-Thin beds connectivity;- Fracture Connectivity;

Leaking Elements:

- Fault (zone) permeability;- Seal integrity;

Different Mudstone Textures from core

Facies B Facies CFacies A

Facies D

Defined are: Four dominant texture types:

A - high clay content mud flow;B - debris flow deposits;C - thin bedded sequence;D – thin, more laterally continuous and persistent debris flow deposits;

Basic facies defined at Wales outcrops

Each faciess is characterised by a specific internal architecture(i.e. internal geometry) indicated as its texture.

Modelling steps:

- Define Clay content from image: a) by linear “projection” of the gray colour scale to clay content range ; b) by recognition of the lighter colours as degree of coarse silt content and then calculation of the clay% based on an established correlation;

- Porosity calculation based on Clay% and user-defined Effective Stress (Yang and Aplin 1998);

-Vertical and Horizontal permeability calculated from porosity based on correlations obtained by Yang and Aplin (1998);

We Always should mind the artefacts imposed from the image quality. Needed is a calibration vs. real experiments

NZ1

NZ2

Expected result

Intermediate texture

Flow Modelling results(equivalent permeability)Texture Modelling

~ 1 m scale

(Stochastic Simulation)

Model ZZ1 Parameters , σeff = 7 MPa

Picture Clay % Porisity %

Kh [nD] Kv [nD]

Model ZZ1 Flow results, σeff = 7 MPa

Flow in X direction

Pesssure distribution Flux (Stream lines)

Model ZZ1 Flow results, σeff = 7 MPa

Flow in X direction

Pesssure distribution Flux (Stream lines)

Model NZ Flow results, σeff = 7 MPa

Flow in Y direction

Pesssure distribution Flux (Stream lines)

Model NZ Flow results, σeff = 7 MPa

Flow in Y direction

Pesssure distribution Flux (Stream lines)

NZ1

NZ2

Upscaled Kh and Kv for twomodels at different Effectife Stress ( 7, 15 , 23 , 45 MPa)

NZ1

NZ1

NZ1

NZ1

NZ1

NZ1

NZ1

NZ1

NZ2

NZ2

NZ2

NZ2

NZ2

NZ2

NZ2

NZ2

Upscaled Kh and Kv as functions of Eff. Stess. Models NZ1 and NZ2

0.1

1

10

100

1000

0 10 20 30 40 50

Effective Stress [MPa]

Lo

gar

ith

m o

f U

psc

aled

Kh

& K

v [n

D]

NZ1 NZ1 Kh [nD]

NZ1 NZ1 Kv [nD]

NZ2 NZ2 Kh [nD]

NZ2 NZ2 Kv [nD]

Model Ki Equation R2

NZ1 Kh Ln (Kh) = 20431 * σeff ^(-2.3756) 0.9935

NZ1 Kv Ln (Kv) = 11234 * σeff ^(-2.6833) 0.9964

NZ2 Kh Ln (Kh) = 46121 * σeff ^(0.9956) 0.997

NZ2 Kv Ln (Kv) = 28516 * σeff ^(-2.7381) 0.997

Conclusions

- Permeable thin bed connectivity is an important factor for the mudstone sealing efficiency;

-Upscaled flow properties highly depends on mudstone texture – defined heterogenity;

- Previous experience on HC leakage could be used as a basis for evaluation of the mudstone CO2 sealing efficiency;

B1.1a Permeability modelling

C1.1a Caprocks and Seals: Permeability modellingAndrew Aplin (Newcastle), Kunco Kurtev (Newcastle) with some advice from Heriot WattPurpose: Estimate potential relaibility of caprocks to ascertain whether they are able to retain chemically active CO2 fluids for appropriate timescales

Establish relative permeability of key caprock units - NewcastleHow does site specific situation effect this? Storage via residual immobile phases while it's migrating?What are the critical leak points/flow paths?Need to take into account physical processes and be able to test models etc - how do you do that?Discuss what field measurements should be made - Cambridge? (e.g. Utsira Sand?)