Erno Takacs 1, Zoltan Hajnal 1, Bhaskar Pandit 1 1 Department of Geological Sciences, U of S ______________________________________________________ Joint Scientific Congress of CMOS, CGU, and CWRA May 26-30, 2013, TCU Place, Saskatoon, Saskatchewan KEEFE LAKE AREA FULL WAVE SONIC LOGGING

 INTERGRATED WELL LOG AND SEISMIC DATASETS UTILIZED IN THIS STUDY  BRIEF OVERVIEW OF THE ELASTIC ROCK PROPERTIES (POISSON’S RATIO, LAMBDA, AND MU)  CORRELATION BETWEEN THE SEISMIC DATA AND ELASTIC ROCK PROPERTIES DERIVED FROM FULL WAVE SONIC LOGS  POTENTIAL OF THE SEISMIC AMPLITUDE VERSUS OFFSET ANALYSIS IN URANIUM EXPLORATION  CONCLUSIONS

Line-4 Line-13 AEROTEM Total Field Magnetic map (Grid spacing: 40 m) Borehole-B Borehole-A Line-4 Line-5 Line-6 Line-13 Two boreholes with Full Wave Sonic (FWS) surveys provided P and S-wave velocity data from the sandstone and basement sequences down to 552 and 357 m depths. (UC depth is around 180 m).

 Compressional wave velocity (V P )V P = [(λ + 2μ)/ρ] 1/2 Can be obtained from FWS logging  Shear wave velocity (V S )V S = (μ/ρ) 1/2 Can be obtained from FWS logging  Rho (ρ) is the density of the rock. ________________________________________________________________________________________________  Lambdaλ = ρ(V p 2 – 2V S 2 ) First Lame parameter `incompressibility`  Muμ = ρV S 2 Second Lame parameter `rigidity`  Poisson`s ratioσ = (V P 2 - 2V S 2 )/2(V P 2 - V S 2 )Ostrander, 1984 (gas sands) ________________________________________________________________________________________________ Undeformed schematic rock volume Deformation under shear stress Deformation under compressional stress Lambda, Mu, Rho After Goodway, 2007 Lambda, Mu, and Poisson’s ratio are related to the stiffness of the rock; in other words to the resistance of the rock against the longitudinal and transversal stresses.

After Goodway, 2007 clastic sedimentary rocks After Ikelle and Amundsen, 2005 clastic sedimentary rocks

FWS UC The light green trace is the zero-offset synthetic derived from V P and Rho. Closer look at the transition zone:

high low medium

low high low Poisson’s ratio, Lambda*Rho, and Mu*Rho parameters of the different lithologies can be separated into distinct clusters not only in clastic sediments but also in crystalline environment.

LithologyVPVP Poisson`s ratioLambda*Rho Mu*Rho 1) Open fractures low high 2) Clay filled fractures lowhigh low 1)The elastic parameters obtained from well-log measurements (FWS) are significant indicators for the fracture and alteration zones. Such zones are considered as possible locations of uranium mineralization in the Athabasca Basin. 2)Based on successful petroleum exploration techniques, elastic parameters can be estimated from properly processed (pre-stack) surface seismic data - in a much more cost effective way than drilling. However, some well- log data are always necessary for the successful analysis. HOW CAN WE DO THAT? Note: Effect of the silicification has been investigated in a nearby exploration area (Hajnal et al., 2010). Amplitude Versus Offset (AVO) analysis of the surface seismic observations

Borehole-ABorehole-B Line-4 75 m high

Borehole-ABorehole-B Line-4 75 m

low Clay alteration? LithologyPoisson`s ratioLambda*Rho Mu*Rho Clay filled fracture zone high low ? AVO inversion provides a tool to extend the well-log information along the seismic profiles with estimation of the elastic parameters from properly processed pre-stack seismic data (Russell and Hampson, 2006). Borehole-ABorehole-B Line-4 75 m

Lithology V P (m/s) V S (m/s) Poisson`s ratio (unitless) Lambda*Rho (GPa*g/cc) Mu*Rho (GPa*g/cc) Crystalline basement as a background Pegmatite intrusion Open fracture zone Clay filled fracture zone Model parameters: Theoretical AVO model based on the FWS data (Borehole-A and B): Pegmatite Open fractures Clay filled fractures Gneiss Top of pegmatite Top of open fractures Top of clay filled fractures Theoretical AVO responses

 Poisson’s ratio, Lambda*Rho, and Mu*Rho parameters of the different lithologies can be separated into distinct clusters not only in clastic sediments but also in crystalline environment.  Poisson’s ratio, Lambda*Rho, and Mu*Rho parameters are significant indicators of the fracture and alteration zones in hard-rock environment.  AVO analysis might be a useful tool to detect fracture and alteration zones from properly processed (pre-stack) seismic data in the Athabasca Basin. However, there are requirements to perform a reliable AVO analysis: 1)The thickness of the investigated zones have to be larger than the seismic resolution. 2)Reflections with reasonable S/N ratio have to be observed from the investigated zones. 3)The investigated zones have to show distinct AVO responses in the area of exploration.

We would like to thank Athabasca Uranium Inc. for the permission to publish this study carried out on the Keefe Lake property and SEMM Logging Borehole Geophysics for performing the unique Full Wave Sonic measurements. Special thanks to ALT Advanced Logic Technology (WellCad), Landmark Graphics Corp. (ProMAX), Schlumberger Ltd. (GeoFrame), and Hampson-Russell Software and Services (AVO) for their support provided to our Seismic Laboratory at Department of Geological Sciences, U of S.

Goodway, B. 2001: AVO and Lame constants for rock parameterization and fluid detection. CSEG Recorder, June 2001, Hajnal, Z., White, D.J., Takács, E., Györfi, I., and others 2010: Application of modern 2-D and 3-D seismic-reflection techniques for uranium exploration in the Athabasca Basin: Canadian Journal of Earth Sciences, 47, Ikelle, L.T., and Amundsen, L. 2005: Introduction to petroleum seismology. Investigations in geophysics No.12, Society of Exploration Geophysicist (SEG), pp. 46. Ostrander, W.J. 1984: Plane wave reflection coefficients for gas sands at nonnormal angles of incidence. Geophysiscs, Vol. 49, No. 10, Russell, B., and Hampson, D. 2006: The old and the new in seismic inversion. CSEG Recorder, December 2006, 5-11.

QUESTIONS? THANK YOU FOR YOUR ATTENTION!