Application of Mechanical and Mineralogical Rock Properties to Identify Fracture Fabrics in the Devonian Duvernay Formation in Alberta

Transcription

1 Application of Mechanical and Mineralogical Rock Properties to Identify Fracture Fabrics in the Devonian Duvernay Formation in Alberta Presented by Mehrdad Soltanzadeh, Ph.D., P.Eng.

2 Duvernay Project, Study Area and Geology Study Area Study Area Geology (Source: Switzer et al., 1994)

3 900 m of Detailed Core Description for 29 Wells (Source: Switzer et al., 1994)

4 Core-based Stratigraphy Idealized Core-based Parasequence/TR Cycle in the Upper Duvernay Shale (Source: Switzer et al., 1994)

5 Stratigraphic Depositional Model

6 Observed Fractures in Duvernay (a) (b) (c) (d) (e) (f) (g) (h) Examples of fracture fabrics observed in the Duvernay Formation cores: (a) subvertical fracture, (b) parallel set of subvertical fractures, (c) conjugate set of sub-vertical planar fractures (arrows) on bedding plane, (d) hackle plume on fracture surface, (e) polished slip faces (PSF), (f) bedding plane fragments of core in Figure 4e showing indistinct PSF surfaces with striae, (g) cleavage lineation on bedding-parallel core surface with oblique calcite-cemented microfracture (arrow), (h) bed-parallel parting (BPP) or core disking.

7 Fractures and Geomechanics

8 Mechanical Rock Properties Lab Tests Uniaxial/Triaxial Hardness Multi-stage Multi-stress Ultrasonic Brazilian Mechanical Properties Static/Dynamic Properties Strength Properties Anisotropy Tensile Strength Logs Sonic/Dipole Sonic Cross-dipole Sonic Density Mechanical Properties Dynamic Elastic Properties Strength Properties Anisotropy

9 Log-based Elastic Properties Ireton F Ireton F Ireton D Ireton C Ireton B Ireton A Duvernay C5 Duvernay C4 Duvernay C3 Duvernay C2 Duvernay C1 Duvernay B Duvernay A (a) (b) Dynamic Poisson s Ratio Dynamic Young s Modulus (GPa)

10 Lab-based Elastic Properties Static Poisson s Ratio Dynamic Poisson s Ratio

11 Frequency Effect of Fluid Type and Pressure? Ireton Duvernay Poisson s Ratio

12 Depth (m) Static vs. Dynamic

13 TOC from SRA (%) Quartz Volume from XRD (%) Petrophysics (a) Calculated Quartz Volume (V/V) (b) Calculated TOC (%)

14 Mineralogy and Mechanical Properties Data from 16 wells Data from a key well

15 Investigating Brittleness So-called Brittleness Index suppose to help with identifying brittle rock from ductile rock. This is an ambiguous definition with different interpretations. Both science and experience confirm that fracturing behaviour cannot be limited to a small number of attributes such as elastic properties. However, it may be possible to integrate these data with other information and come up with some locally-defined parameters that act as proxies for identifying the fraccability of the rock.

16 Trying Different Indices Mineralogical Brittleness Indices: BR Dolomite BR Clay = 1 = Dolomite[+Quartz] All Minerals Clay [+TOC] All Minerals 100 Mechanical Brittleness Indices: 100 Commonly-used Parameter Used in This Study BR Rickman = 1 2 E E min + ν max ν 100 E max E min ν max ν min Commonly-used Parameter E ps = E 1 ν 2 = 2G 1 ν Used in This Study

17 E ps Comes from Fracture Mechanics Fracture Geometry PKN Fracture Model Stress Profile

18 Comparison of Different Indices Ireton F Ireton F Ireton D Ireton C Ireton B Ireton A Duvernay C5 Duvernay C4 Duvernay C3 Duvernay C2 Duvernay C1 Duvernay B Duvernay A (a) (c) Ireton F Ireton F Ireton D Ireton C Ireton B Ireton A Duvernay C5 Duvernay C4 Duvernay C3 Duvernay C2 Duvernay C1 Duvernay B Duvernay A Rickman s Brittleness Index (%) (b) (d) Ireton F Ireton F Ireton D Ireton C Ireton B Ireton A Duvernay C5 Duvernay C4 Duvernay C3 Duvernay C2 Duvernay C1 Duvernay B Duvernay A Plane-strain Young s Modulus (GPa) (c) Brittleness Index based on Dolomite and Quartz (%) (d) Brittleness Index based on Clay (%) El Diablo The best correlation exists between these two parameters.

19 E ps vs. BR Clay Effective Porosity

20 Fractures on Cores and Image Logs Logs Image Log Graphic Core Description BR Clay Gamma YM PR PS-YM BR Rickman

21 Fractures and Rock Properties Fraccablity Range

22 Fracture Types and Rock Properties Rock Properties Core Description Sonic PR YM BR SP. GR Hardness

23 Identifying Fracture Types (a) (b)

24 Hardness vs. Log-based Properties

25 Conclusions Shale behaviour in the field is strongly affected by in-situ conditions, so, integrating field and lab measurements needs to be performed with extreme caution. Different plays may need to be treated differently as shown for the brittleness index. Observed fractures on the core and image logs are probably one of the most trustworthy criteria to determine rock s fraccability. Rock properties, along with stresses, have identifiable effects on the formation of different fracture fabrics. Data integration in unconventional plays can help with more precise characterization of the play behaviour and provides opportunities for application of more efficient approaches for development of these plays.

26 Acknowledgments Co-authors: Graham David, Graham Davies Geological Consulting Ltd. Amy Fox, Canadian Discovery Ltd. David Hum, Core Laboratories LP Nasir Rahim, Canadian Discovery Ltd. Trican Geological Solutions Ltd. Albert Cui, Ken Glover. Canadian Discovery Ltd. Sarah Hawkes, Ching Zhu, Leydy Garcia, Susan Wang, Suzie Jia. Seven Generations Energy Ltd.