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A Time-Lapse Seismic Modeling Study forCO2 Sequestration at the Dickman Oilfield

Ness County, Kansas

Jintan Li

April 28th, 2010

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Outline

• Background/Introduction

• Methods

• Preliminary Results

• Future Work

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Background

• Area: Dickman Field, Kansas• Interest: CO2 Sequestration Target

• Deep Saline Aquifer - primary• Shallower depleted oil reservoir - secondary

• Reservoir Characterization: • seismic processing, inversion, volumetric attributes,

log analysis, petrophysics, reservoir simulation, and 4D (my part of work)

• Funded by DOE (2009-2012)

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Dickman FieldLocation: Ness County Kansas State

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Local stratigraphic column based on the well log and mud log information from Dickman Field

First target

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Goal of 4D Seismic

To monitor the reservoir at various time:

• Fluid-flow paths

• CO2 movement and containment

• Post-injection stability

• Reservoir properties, etc.

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Framework

• Reservoir Flow Simulation• Computer Modeling Group (CMG)

• Gassmann Fluid Substitution

• Seismic Simulation Candidates• Convolution model• Full Wave Forward Modeling

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Ford Scott Limestone

Cherokee Group

Low Cherokee Sandstone

Mississippian Carbonate

Low Mississippian carbonate

Flow Simulation Model

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3D Flow Simulation Volume

Generated from CMG as input for fluid substitution. Each simulation grid contains:

• P,T, porosity

• Sw,So,Sco2

• API, G, Salinity

• fluid density and mineral density/ fluid saturated density

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Work Flow: Fluid Substitution and Seismic Modeling

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Fluid Substitution

• Kmin: Voigt-Reuss-Hill (VRH) averaging (Hill, 1952)

• Kfluid: brine/water + CO2 or Oil• Kdry

• Initial Ksat estimation from well logs (Vp,Vs and rho)• Derive Gassmann’s equation into Kdry, which is a

function of Ksat,Kmin,Kfluid

• Ksat: Gassmann’s equation• sat: shear sonic log and density log

Vsat: from Ksat and sat Ro: from impedance contrast

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Preliminary Results

• Reflection coefficients variations versus changes of fluid properties

– Reflection Coefficient between Mississippian and Base of Pennsylvanian

– Reflection Coefficients of flow simulated model after 250 years of CO2 injection

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3D Seismic area, time slice at the Mississippian and profile A-A’.

Target

Base of Penn: Lower Cherokee (LCK) Sandstone~20% porosity

Mississippian: porous structure unconformitylimestone/dolomite/calcite~20% porosity

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MSSP and Base_P

Formation

Base of Pennsylvanian

Vp Density Vs

Vp/Vs=1.7 for Limestone

Averaged from well log

Averaged from well log N/A

Upper Mississippian

Fluid subsitution

Mineral content: 30% dolomite

70% calcite

Fluid substitution

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Crossline

( y cord:m)

Inline ( x coordinate:m)

Sco2=0.5

Sbrine=0.5

Reflection coefficient range: min=-0.0267 max=0.3872

Example2: Ro (Miss and Base_Penn)Phi

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Crossline

( y cord:m)

Inline ( x coordinate:m)

Sco2=0.9

Sbrine=0.1

Reflection coefficient range: min=-0.3001 max=0.0983

Example2: Ro (Miss and Base_Penn)Phi

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Case II: Reflection coefficients (Ro) after 250 years of CO2 injection (layer 1 to layer 16: from 150-2350ft ss)

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Future Work

• Seismic simulation with the convolution model as a start

• Incorporate full wave modeling into the seismic simulation

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Acknowledgement

• Dr. Christopher Liner (PI)

• June Zeng (Geology)

• Po Geng (Flow simulation)

• Heather King (Geophysics)

• CO2 Sequestration Team

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END

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• Mississippian: porous structure unconformity• limestone/dolomite/calcite• ~20% porosity

• Base of Penn: • Lower Cherokee (LCK) Sandstone• ~20% porosity

Major Formations ( depleted oil Reservoir)

22Inline ( x coordinate:m)

Sco2=0.5

Sbrine=0.5

Reflection coefficient range: min=-0.0267 max=0.3872

Case I: Ro (Miss and Base_Penn)

Crossline

( y cord:m)

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Sco2=0.9

Sbrine=0.1

Reflection coefficient range: min=-0.3001 max=0.0983

Case I: Ro (Miss and Base_Penn)

Inline ( x coordinate:m)

Crossline

( y cord:m)

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Case II: Reflection coefficients (Ro) after 250 years CO2 injection (layer 17 to 32)

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Kmin (MSSP)

• Dolomite (Vdolo=70%) of the volume

• Calcite (Vcal=30%)

Voigt-Reuss-Hill (VRH) averaging (Hill, 1952)

Kdolo=83(Gpa) Kcal=76.8(Gpa)

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Kfluid

• Kbrine (Batzel and Wang, 1992)

• Koil (Batzel and Wang, 1992)

• Kco2 (calculated by KGS online source)

Wood’s Equation:

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Temperature and Pressure T,P varies with depth (Carr, Merriam and Bartley,

2005)

• Mississippian

T = 0.0131(depth) + 55

• For the deep saline aquifer (Arbuckle group)

T = 0.0142(depth) + 55

• Mississippian

P = 0.476(depth)T: Fahrenheit

P: psi

Depth: ft

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Kdry

Shear modulus is calculated by averaging the shear wave sonic and density log

Kdry can be obtained by rewriting the Gassmann’s equation:

Intial Ksat estimation

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Ksat

• Gassmann’s Equation

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Reflection Coefficients Calculation

• Impedance: Z=Vp*Rho_sat• Reflection coefficient:

i=1,N-1

P wave

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Some Fixed Input Parameters

• Salinity: 45000ppm

• API for CO2: 37

• Rho_CO2=46.54*0.01601846 g/cm3

• Averaged shear log velocities: Vp=5420m/s Vs=1806m/s (Vp/Vs=1.7)

•

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Kfluid: Kco2

http://www.kgs.ku.edu/Magellan/Midcarb/co2_prop.htmlBy Kansas geological survey

Given T, P:

CO2 properties can be calculated

Missipian average depth:4424ft

T=4424*0.0131+55=110F

P=0.476*4424= 2100 psi

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4D Seismic Phases

• Phase I: understand the effect of reservoir fluid properties on the seismic response

• Phase II: apply the fluid changes to the depleted oil reservoir

• Phase III: apply the fluid substitution throughout the whole zone of interest

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CO2 Safe Storage

• Four trapping Mechanisms

– Structural trapping

– Solubility trapping

– Residual gas trapping

– Mineral trapping