Pore Scale Analysis of Oil Shale/Sands Pyrolysis

Transcription

1 Pore Scale Analysis of Oil Shale/Sands Pyrolysis C.L. Lin, J.D. Miller, and C.H. Hsieh Department of Metallurgical Engineering College of Mines and Earth Sciences University of Utah

2 Outlines Introduction Research Objectives Multiscale X-ray micro/nano Computed Tomography Lattice-Boltzmann Model Results and Discussion Conclusion Further Research

3 Introduction Non-invasive non-destructive imaging techniques (x-ray CT) can provide improved understanding of transport phenomena in oil sand/oil shale resources The pore network structure established from CT analysis is used as a basis for flow simulation using the LB method.

4 Outlines Introduction Research Objectives Multiscale X-ray micro/nano Computed Tomography Lattice-Boltzmann Model Results and Discussion Conclusion Further Research

5 Research Objectives CT characterization of the pore network structure for selected oil sand/oil shale resources, LB simulation of flow through pore network structures to predict transport properties, such as permeability, and CT analysis of pore network structure during pyrolysis reactions at different temperatures.

6 Outlines Introduction Research Objectives Multiscale X-ray micro/nano Computed Tomography Lattice-Boltzmann Model Results and Discussion Conclusion Further Research

7 Conventional Projection 3D View Slice Views

8 Source Detector Sample Stage

9 Shale Silted Sandstone Tar Sand Sandstone Rock core 50 nm 150 nm 1 μm 10 μm 45 mm nanoxct module 150 nm resolution and 66 um FOV 50 nm resolution and 20 um FOV Lengthscale Multi-Length Scale CT MicroXCT module 0.8 um resolution and 0.5 mm FOV 20 um resolution and 45 mm FOV

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11 X-ray Micro CT Images - Oil Shale

12 X-ray Nano CT Images - Oil Shale

13 Outlines Introduction Research Objectives Multiscale X-ray micro/nano Computed Tomography Lattice-Boltzmann Model Results and Discussion Conclusion Further Research

14 The Lattice-Boltzmann Method LBM is a Numerical Method, that in contrast to the Standard CFD methods, uses a bottom-up approximation based on the Boltzmann equation and Kinetic Theory From a scale point of view, the LBM is between the Molecular Dynamics Methods and the Navier-Stoke s Equation

15 Context of the Lattice-Boltzmann Method From a scale point of view, the LBM is between the Molecular Dynamics Methods and CFD Solvers

16 The Lattice Boltzmann Model From the Boltzmann Equation and using a BGK (Bhatnagar- Gross-Krook) approximation we get From discretization of velocity, space and time we get to the Lattice-Boltzmann Model Which is equivalent to

17 The Lattice Boltzmann Model Four Basic Components for Fluid Flow Simulation The lattice The streaming and collision scheme structure Equilibrium distribution function Boundary conditions

18 The Lattice D3Q19 Model

19 The streaming-collision structure Problem Initialization streaming collision No, t+1 Convergence? Yes Outputs

20 Computational Issues Processor 1 1 communication 2 Processor 2 3 communication Processor 3 =

21 Outlines Introduction Research Objectives Multiscale X-ray micro/nano Computed Tomography Lattice-Boltzmann Model Results and Discussion Conclusion Further Research

22 Pyrolyzed Oil Shale Samples Sample No. Type Heating Rate Misc ( o C/min) MD-3 drill core 100 N2 flow, 300 o C MD-4 drill core 100 N2 flow, 350 o C MD-5 drill core 100 N2 flow, 400 o C MD-11 1 drill core 1 MD-12 1 drill core 10

23 Reaction Cores (Heating Rate = 1, 10, 100 o C/min)

24 Reaction Cores (Heating Rate = 1, 10, 100 o C/min)

25 Porosity Variation

26 Porosity Variation

27 Porosity Variation

28 Mean Porosity for the Pyrolyzed Oil Shale Cores at Different Reaction Temperatures Sample No. Temp. ( o C) Heat Rate ( o C/min) Mode Mean Porosity (%) MD N 2 flow 9.44 MD N 2 flow Md N 2 flow 13.36

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30 X-ray Micro CT Images Oil Shale after Pyrolysis MD-5 (400 o C, N2 flow, voxel resolution = 5.07 μm)

31 X-ray Nano CT Images - Oil Shale after Pyrolysis

32 X-ray Micro CT Images Oil Shale after Pyrolysis MD-5 (400 o C, N2 flow, voxel resolution = 5.07 μm)

33 LB Simulation of Saturated Flow through Oil Shale after Pyrolysis velocity Region A (Nano CT) Region B (Micro CT) Calculated permeability ~ md (millidarcies) ~ 3920 md (millidarcies)

34 Effect of Temperature Pyrolyzed Oil Shale 300 o C 6.77 darcy 350 o C 3.23 darcy 400 o C 3.87 darcy

35 Simulation of Fluid Penetration and Capillary Phenomena in Pore Network Structure Fluid Penetration

36 Simulation of Fluid Penetration and Capillary Phenomena in Porous Media Capillary Number Viscosity Ratio v inlet/outlet velocity μ viscosity of injected fluid n porosity interfacial tension between fluids contact angle Friedman, J. Adhesion Sci Technol. 13(12),

37 Air/Viscous Oil Phase Diagram Lenormand et al J. Fluid Mech. 189, Glucose Soln./ Oil Air/Viscous Oil

38 Simulation of Multiphase Fluid Flow in Oil Sand (Athabasca)

39 Simulation of Multiphase Fluid Flow in Oil Sand (Sunnyside - Utah)

40 Outlines Introduction Research Objectives Multiscale X-ray micro/nano Computed Tomography Lattice-Boltzmann Model Results and Discussion Conclusion Further Research

41 Conclusion Detailed 3D imaging of oil shale core before and after pyrolysis was done to establish the pore structure of the core after reaction using multiscale x-ray CT for imaging. It is evident that x-ray nano computed tomography (XNT) imaging will be required to provide satisfactory pore structure information for the silicate rich zone.

42 Conclusion (Conc.) Scanning of oil shale core samples after pyrolysis at three reaction temperatures (300 o C, 350 o C, and 400 o C) and different heating rates of 1, 10 and 100 o C/min was done to establish the pore structure of the core after reaction using HRXMT for imaging (~ 5 micron voxel resolution). The porosity variation with drill core sample height as measured from the CT data clearly correlates with position of the kerogen layers. The mean porosity of the silicate rich layers inside the reacted core was found to be about 10 % for different reaction temperatures and heating rates.

43 Conclusion (Conc.) 3D software capabilities of LB simulation code for analysis of multiphase fluid flow in porous media have been successful implemented. The pore structure deduced from the images was used for Lattice Boltzmann simulations to calculate the permeability in the pore space. The permeabilities of the silicate rich zone of the pyrolyzed samples were on the order of milli- Darcies, while the reacted core permeabilities of the kerogen-rich zone were very anisotropic and about four orders of magnitude higher.

44 Outlines Introduction Research Objectives Multiscale X-ray micro/nano Computed Tomography Lattice-Boltzmann Model Results and Discussion Conclusion Further Research

45 Further Research Analysis of new, fresh oil shale core and comparison with the initial oil shale samples Calibration for phase identification internal calibration with mineralogical results from QEM/ SCAN. Directional (anisotropic) permeability of the reacted core of new oil shale samples for pyrolysis reactions at different temperatures based on pore network structure by X-ray micro/nano CT (XMT/XNT) analysis coupled with LB simulation. Permeability of the reacted core after pyrolysis reactions under different loading conditions.

46 Acknowledgments Our Special thanks to the Institute of Clean and Secure Energy (ICSE) for their financial support (DOE / DE-FE )