1 A Time-Lapse Seismic Modeling Study for CO2 Sequestration at the Dickman Oilfield Ness County, Kansas Jintan Li April 28 th, 2010

2 Outline Background/Introduction Methods Preliminary Results Future Work

3 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 ( )

4 Dickman Field Location: Ness County Kansas State

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

6 Goal of 4D Seismic To monitor the reservoir at various time: Fluid-flow paths CO2 movement and containment Post-injection stability Reservoir properties, etc.

7 Framework Reservoir Flow Simulation Computer Modeling Group (CMG) Gassmann Fluid Substitution Seismic Simulation Candidates Convolution model Full Wave Forward Modeling

8 Ford Scott Limestone Cherokee Group Low Cherokee Sandstone Mississippian Carbonate Low Mississippian carbonate Flow Simulation Model

9 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

10 Work Flow: Fluid Substitution and Seismic Modeling

11 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

12 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

13 3D Seismic area, time slice at the Mississippian and profile A-A’. Target Base of Penn: Lower Cherokee (LCK) Sandstone~ 20% porosity Mississippia n: porous structure unconformity limestone/do lomite/calcite ~20% porosity

14 MSSP and Base_P Formation Base of Pennsylvanian VpDensityVs Vp/Vs=1.7 for Limestone Averaged from well log N/A Upper Mississippian Fluid subsitution Mineral content: 30% dolomite 70% calcite Fluid substitution

15 Crossline ( y cord:m) Inline ( x coordinate:m) Sco2=0.5 Sbrine=0.5 Reflection coefficient range: min= max= Example2: Ro (Miss and Base_Penn) Phi

16 Crossline ( y cord:m) Inline ( x coordinate:m) Sco2=0.9 Sbrine=0.1 Reflection coefficient range: min= max= Example2: Ro (Miss and Base_Penn) Phi

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

18 Future Work Seismic simulation with the convolution model as a start Incorporate full wave modeling into the seismic simulation

19 Acknowledgement Dr. Christopher Liner (PI) June Zeng (Geology) Po Geng (Flow simulation) Heather King (Geophysics) CO2 Sequestration Team

20 END

21 Mississippian: porous structure unconformity limestone/dolomite/calcite ~20% porosity Base of Penn: Lower Cherokee (LCK) Sandstone ~20% porosity Major Formations ( depleted oil Reservoir)

22 Inline ( x coordinate:m) Sco2=0.5 Sbrine=0.5 Reflection coefficient range: min= max= Case I: Ro (Miss and Base_Penn) Crossline ( y cord:m)

23 Sco2=0.9 Sbrine=0.1 Reflection coefficient range: min= max= Case I: Ro (Miss and Base_Penn) Inline ( x coordinate:m) Crossline ( y cord:m)

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

25 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)

26 Kfluid Kbrine (Batzel and Wang, 1992) Koil (Batzel and Wang, 1992) Kco2 (calculated by KGS online source) Wood’s Equation:

27 Temperature and Pressure T,P varies with depth ( Carr, Merriam and Bartley, 2005 ) Mississippian T = (depth) + 55 For the deep saline aquifer (Arbuckle group) T = (depth) + 55 Mississippian P = 0.476(depth) T: Fahrenheit P: psi Depth: ft

28 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

29 Ksat Gassmann’s Equation

30 Reflection Coefficients Calculation Impedance: Z=Vp*Rho_sat Reflection coefficient: i=1,N-1 P wave

31 Some Fixed Input Parameters Salinity: 45000ppm API for CO2: 37 Rho_CO2=46.54* g/cm3 Averaged shear log velocities: Vp=5420m/s Vs=1806m/s (Vp/Vs=1.7)

32 Kfluid: Kco2 By Kansas geological survey Given T, P: CO2 properties can be calculated Missipian average depth:4424ft T=4424* =110F P=0.476*4424= 2100 psi

33 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

34 CO 2 Safe Storage Four trapping Mechanisms –Structural trapping –Solubility trapping –Residual gas trapping –Mineral trapping