1. Abeer Heikal Ph. D. program 2 – 3 November 2016
Reservoir Geomechanics Research Group [RG]2
Foundation CMG Industrial Research Consortia in Reservoir Geomechanics for Unconventional Resources
Role of Discontinuities on Hydro-Mechanical Characteristics of Shale Caprock overlying SAGD
Abeer Heikal Ph. D. program
2 – 3 November 2016

2. Highlights Assessment of Soft shale caprock integrity
Fundamental field characterization (complex geological framework)
3D DEM
Constitutive properties of intraformational shales (OCR & K)
Deformability of shale caprock (heave/uplift)
Consequences of deformation on flow
Verification

3. Introduction
Caprock is ultimate seal and containment of bitumen (Shen et al. 2014) that can effectively withstand stresses and strains induced from SAGD processes throughout life of reservoir development (Uwiera et al. 2011)
Caprock integrity assessments have become key element in;
design and operation of SAGD projects
selection of maximum steam injection operating pressure
Clearwater formation shales are heavily overconsolidated and as result of their stress history, they generally contain genetic features (e.g. fissures) that will influence how this class of materials behaves as failure conditions are approached (heterogeneity)
Discontinuities (not continuum!) and their constitutive model/s

4. SAGD
Caprock

5. Shale Caprock

6. Scientific Hypothesis
Deformability and strength of hard vs soft rock are different
Implications of caprock analyses as continuum vs discontinuum
To prove
Strength and deformability of hard vs soft rock (3D DEM)
Ratio of discontinuities- to matrix-compliance (Cd/Cm)

7. Scientific Hypothesis Hard versus Soft Rock

8. Scientific Hypothesis Discontinuities’ to Matrix’ Compliance
𝐶 𝑑 𝐶 𝑚 ≤0.001− 𝑓𝑜𝑟 𝐻𝑎𝑟𝑑 𝑟𝑜𝑐𝑘𝑠
𝐶 𝑑 𝐶 𝑚 =0.01− 𝑓𝑜𝑟 𝑚𝑒𝑑. 𝑟𝑜𝑐𝑘𝑠
𝐶 𝑑 𝐶 𝑚 ≥0.1− 𝑓𝑜𝑟 𝑆𝑜𝑓𝑡 𝑟𝑜𝑐𝑘𝑠

9. Objectives Methodology
Developing equivalent continuum for Fractured clearwater shale Soft caprock considering scale and strength anisotropy
Generating fundamental characterization workflow that can be repeatedly applied
Methodology
3D Geomechanical Modelling
Experimental Testing
LiDaR (Discontinuities Statistics)

10. Field-based Geological Characterization LiDaR
Accuracy (no human factor)
Accessibility (remote)
High resolution
Time-effective
Cost-effective
Repeatability
Safety

11. LiDaR Data Processing Engines

12. Clearwater Shale Caprock LiDaR Point Cloud

13. LiDaR Data Processing using CloudCompare
Export *.CSV
Generate Stereogram
Estimate Dip and Dip Direction
Use Plugin FM / Kd Algorithm
Compute Normals
Generate TIN
Crop Point Cloud
Rotate Point Cloud
Register Point Cloud
Field Data Capture

14. Point Cloud Analyses

15. CloudCompare 2795 Planar Facets (Kd-tree Algorithm)

16. CloudCompare 565 Planar Facets Fast Marching (FM) Algorithm

17. Stereonet

18. Discontinuities (2D polygons)
Index
Center (X,Y,Z)
Normal (X,Y,Z)
retro-projection error (RMS)
Horiz_ext: horizontal extension
Vert_ext: vertical extension
Surf_ext: surface of the bounding rectangle (in the facet plane)
Surface
Dip direction
Dip
Family index (if any - see the Classification method below)
Sub-family index (if any - see the Classification method below)

19. Discontinuities Statistics *.CSV

20. MATLAB

21. DEM Study Effect of … With or without discontinuities ?
Try continuum? load and …
Try discontinuum with bedding planes and …?
Try discontinuum with all discontinuities and …?
Compare all? Decide why should include or not? If yes? How much should be included?

22. Deterministic DFN (Disks of Equal Area)

23. Discontinuities Planes in 3DEC

24. Discontinuity Inclusion on Deformability (heave)

25. Discontinuity Inclusion Analysis on Deformability – Results
Continuum modeling of caprock underestimates heave deformation (0.28 m versus 1.69 bot. of caprock)
In discontinuum modelling, discontinuities carry up good amount of deformation
Discontinuities deform (some open!), consequently caprock’ flow properties change

26. Conclusions
Constitutive models developed for hard rocks CAN NOT be applied to soft rocks
There is need for;
Better understanding deformability of rock mass as system (matrix + discontinuities)
Realistic characterization of clearwater shale caprock
Equivalent continuum model of soft caprock
Relation between caprock deformability and flow!

27. Reservoir Geomechanics Research Group [RG]2
Foundation CMG Industrial Research Consortia in Reservoir Geomechanics for Unconventional Resources
Questions?

28. LiDaR Data
American Society of Photogrammetry and Remote Sensing (ASPRS) LASer (*.LAS) 3D point cloud data
Processing using free trails or open source (cost effective)
File size 0.4 – 0.6 GB
More than 11,800,000 points in cloud
Each point (x, y, z, and laser/light intensity)

29. FM / Kd-tree Algorithm

30. Discontinuities statistics

31. Discontinuity to Rock Matrix Compliance Ratio (𝐂d/𝐂𝐦)

32. Discontinuity to Rock-Matrix Compliance

33. Hard versus Soft Rock mass element Property
Marble (Weizhong et al., 2011)
Shale (Zadeh & Chalaturnyk, 2015)
Rock matrix
Bulk density, ρ (kg/m3)
2713
2129
Shear modulus, G (GPa)
20*
0.179*
Bulk modulus, K (GPa)
33*
0.833*
Cohesion, C (MPa)
19.44
0.150
Friction angle, Φ (o)
43.8 30
Young’s modulus, E (GPa) 50
0.5
Poisson’s ratio, ν
0.25
0.4 (Kitahara et al.1974)
Dilation angle (o) 20
Tensile strength (MPa)
UCS (MPa)
100
1 – 8
failure
0.003
0.02
Discontinuities
Joint, Kn (GPa/m) 17
Joint, Ks (GPa/m) 9
Cohesion (MPa)
0.07
Friction (o)
30.44

34. 3DEC caprock model
boundary stress =1700e3 gravity 9.81,0,0 ;Strain Softening (rock matrix) zone model strainsoften density 2.129E3 bulk 833e6 shear 178e6 friction 30 & cohesion 150e3 tension 0.434e6 dilation 20 & ftable 1 ctable 2 ttable 4 dtable 3 table 1 0,30 .01,9.8 table 2 0,150e3 .01,100e3 table 3 0,20 .01,0 table 4 0,0.434e6 .01,0.0 ; discontinuity material property change dfn 1 jmat 1 2 prop jmat 1 jfric 20 jcoh 1 jkn 1e5 jks 1e5 ; discontinuity prop jmat 2 jfric 30 jcoh 150e3 jkn 5e6 jks 5e6 ;=matrix

35. Clearwater shale caprock
E (MPa) = 46 – 223 (BigGuns 2013) 75 – (Uwiera-Gatner et al. 2011) 960 – (Khan et al. 2011) UCS (MPa) = 0.15 – 0.53 (BigGuns, 2013) 0.2 (Thomas & Sands, 2010 & Uwiera-Gatner et al. 2011) 0.3 – 1.9 (ShafieZadeh &Chalaturnyk 2015) 0.8 – 2.1 (Laricina Energy Ltd., 2012) 2.3 – 11 (Laricina Energy Ltd., 2012) 3.1 – 3.5 (Khan et al. 2011) 7.5 – 8.5