e b . t n CT in Geology e g u . Marijn Boone t c Department Geology and g Soil Science – UGCT u . w w w
e Overview presentation b . t n • History: review papers e • g Applications of CT in geology u • 3D grain analysis . • 3D petrography t c • Pore analysis g • Fluid flow analysis u • Future innovations . w • REV - multiscale w • Dynamic imaging w • In situ scanning
e First Geological applications b . t n • Paleontology e g (Conroy & Vannier, 1984 and Haubitz et al., u 1988) . t c – CT for irreplacable fossil samples ( non destructive g analysis ) u . w w w Conroy & Vannier, 1984
e First Geological applications b . t n • Paleontology (Conroy & Vannier, 1984 and e g Haubitz et al., 1988) u – CT for irreplaceable fossil samples (non . t c destructive analysis) g • Meteorites (Arnold et al., 1982) u . – One of a kind sample: w Allende Meteorite w w
e First Geological applications b . t n • Petroleum engineering (Wellington and e g Vinegar, 1987 and WithJack, 1988) u 2 phase fluid flow experiments on cores ( high . t c temporal resolution ) g u . w w w After Wellington and Vinegar, 1987 After Wellington and Vinegar, 1987
e First Geological applications b . t n Medical CT in multiple fields of geology by early e g 90s u - Porosity of soils . t c - Sediment morphology in cores g Medical CT - Faulting in rocks u Spatial - … resolution of . w 250 µm w w
e First Geological applications b . t n • End of the 90s: higher resolution e g – shape and size of individual pores, minerals, grains u and factures . t c – Mainly synchrotron facilities (cost and availability) g – Around 2000: lab based micro-CT systems in u geology . w w w
e First Geological applications b . t n e g u . t c g u . w X-ray source w Sample w X-ray detector
e First Geological applications b . t n e g u . t c g u . w w w
e First Geological applications b . t n e g u . t c g u . w w w 2D 3D
e First Geological applications b . t n e g u . t c g u . w w w 2D 3D
e First Geological applications b . t n Resolution e g High resolution only for small u samples . t c g u . w d 1 w R 1 s M M w 250 µm R: resolution SDD d: resolution detector M M: magnification SOD s: spot size X-ray source
e First Geological applications b . t n e Grey value g µ(x,y,z) : local attenuation u coefficient . t c Proportional to mass density g quartz - clay u . w Strongly depending on atomic w number w quartz (Si) – zircon (Zr)
e b . t n e g u . t c g u Applications in geology . w GRAIN SIZE ANALYSIS: w DETERMINING THE GRAINS SIZE, SHAPE AND w DISTRIBUTION FROM THE 3D IMAGE
e Applications: grain size analysis b . t n Grain size distribution: e g - Sieving u . t - Measuring on thin section c g u - Sorting . w w w - Determine shape and angularity
e Applications: grain size analysis b . Original image Segmentation based on grey scale t n e g u . t c g u Maximum opening . w w w
e Applications: grain size analysis b . Original image Segmentation based on grey scale t n e g u Maximum opening . t c g Equivalent diameter = Diameter of sphere with this volume u Watershed separation Maximum opening . w w w
e Applications: grain size analysis b . t n e g u . t c g u . w w w
e b . t n e g u . t c g u Applications in geology . w 3D PETROGRAPHY: w DETERMINING THE MINERAL DISTRIBUTION IN 3D w
e Applications: 3D petrography b . t n • X-ray CT: no direct chemical information e g – Multi-energy scanning: density & atomic number u • Synchrotron: mono-energetic . t c • Lab based microCT : poly energetic (challenging) g u 1,000 Linear attenuation coefficient . Quartz w Chalcopyrite 100 Attenuation (cm -1 ) Malachite w Barite w 10 1 keV 0 0 20 40 60 80 100 120 140 160
e Applications: 3D petrography b . t n • X-ray CT: chemical information e g – Multi-energy scanning: density & atomic number u – Data fusion: combining different techniques . t c • XRF (synchrotron & lab system) g u . w ~ 3.5 mm w w B. De Samber et al, 2008 Analytical and Bioanalytical Chemistry
e Applications: 3D petrography b . t n • X-ray CT: chemical information e g – Multi-energy scanning: density & atomic number u – Data fusion: combining different techniques . t c • XRF (synchrotron & lab system) g • SEM(SEM-EDS) u µCT SEM-EDS . w w w
e Applications: 3D petrography b . t n e g Cu Si S u . t c g Ba 2D µXRF mapping Fe EDAX EAGLE-III µ- u probe on the . w surfaces of the sample w S Si w Fe Ba Cu
e Applications: 3D petrography b . t n e Quartz SiO 2 g u Malachite . t Cu 2 CO 3 (OH) 2 c g Chalcopyrite u CuFeS 2 . w Fe-rich w ground mass w Barite BaSO 4
e Applications: 3D petrography b . t n e Quartz SiO 2 g u Malachite . t Cu 2 CO 3 (OH) 2 c g Chalcopyrite u CuFeS 2 . w Fe-rich w ground mass w Barite BaSO 4
e b . t n e g u . t c g u Applications in geology . w 3D PORE CHARACTERIZATION: w DETERMINING POROSITY AND PORE SIZE w DISTRIBUTION
e Applications: 3D pore characterization b . t n Before CT: e g 3D pore structures based on 2D thin sections or u SEM images . t c g u . w w µCT & image analysis: visualize and analyze complex w pore structure and its connectivity
e Applications: 3D pore characterization b . t n e g u . Porosity calculation t c g Labeling different pores according to: - size u - orientation . - surface w - … w Pore network extraction w Pore throats
e Applications: 3D pore characterization b . t Oolithic limestone (resolution 5.6µm) n Partially filled with water e g u . t c g u . w w w
e Applications: 3D pore characterization b . t Oolithic limestone (resolution 5.6µm) n Partially filled with water e Analyze distribution of water g and air in pore structure u . t c g u . w w w
e Applications: 3D pore characterization b . t Oolithic limestone (resolution 5.6µm) n e g u . t c g u . w w w
e Applications: 3D pore characterization b . t Oolithic limestone (resolution 5.6µm) n e g u . t c g u . w w w 6,8 % residual water 8,5 % air
e Applications: 3D pore characterization b . t n Importance of water distribution e in rock: Frost weathering g u Visualize water uptake in building material . t c Preferential uptake along g certain zones in the rock u . w w w
e Applications: 3D pore characterization b . t n Frost weathering e g u . t c g u . w w w
e b . t n e g u . t c g u Applications in geology . w FLUID FLOW ANALYSIS: w MODELLING FLUID FLOW THROUGH THE PORES w
e Fluid flow analysis b . t n Computational single phase flow Extracting pore e intensive: Lattice Boltzmann network model Cluster Computer g method needed for u calculation . t c g u . Permeability w value in Darcy w w
e Fluid flow analysis b . t n More than one fluid: e Pore Network Modelling Mineral grains g Pore space u . t c g u . w w w
e Fluid flow analysis b . t n e Water displaced by non wetting phase g u . t c g u . w w w
e Fluid flow analysis b . t n CCS project in Svalbard e (Norway) Underground CO 2 g storage in a geological reservoir u . t c g u . w w Porosity = 10% w Percolating porosity = 9% Permeability = 11 mD
e Fluid flow analysis b . t n e Pumping CO 2 into the underground: g Pore network model from CT Water displaced by CO 2 (= 87% CO2) u . t c g u . w w w
e Fluid flow analysis b . t n e Pumping CO 2 into the underground: Stop CO 2 injection and return water: g Water displaced by CO2 (= 87% CO 2 ) CO 2 displaced by water (= 60% CO 2 trapped) u . t c g u . w w w
e b . t n e g u . t c g u Future Challenges . w REV: REPRESENTATIVE ELEMENTARY w VOLUME AND UPSCALING w
e REV and upscaling b . t n High resolution scan representative for an entire rock or core? e = small sample g u . t c g u or even for a quarry or reservoir? . w w w 5 mm Representative ?
e REV and upscaling b . t Carbonate reservoirs: n Complex texture e Very heterogeneous concerning porosity g Interparticular u & . Intraparticular Fractures t c porosity g u . Moldic porosity w w Vuggy porosity w Intercrystal porosity AAPG, 77
e REV and upscaling b . t Upscaling n Combining information from different sample sizes and e resolutions to capture all the different porosity types g u Larger core – medical CT (500 µm³) Subsample – micro CT (12 µm³) . t c g u . w w w Capture large vugs and fractures
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