Investigating the potential of using conductive or permeable proppant particles for hydraulic fracture characterization

Delineation of the stimulated region of a hydraulic fracture is a key component for analyzing the success of a fracture treatment. The proppant, used to keep the fracture pathways open, provides a medium through which the physical properties of the fractured volume can be artificially altered. If this alteration is significant, the opportunity for a geophysical analysis of this problem is introduced. We suggest including magnetic and electrically conductive particles to the proppant to provide an electromagnetic geophysical target. In this study we use a simple model to investigate the desirable physical properties of the fractured volume from the perspective of signal detection.

Extended abstract available at: http://library.seg.org/doi/pdf/10.1190/segam2013-1372.1

1. slide 1 SEG Houston 2013 The University of British Columbia Geophysical Inversion Facility gif.eos.ubc.ca Lindsey J. Heagy* & Douglas W. Oldenburg Investigating the potential of using conductive or permeable proppant particles for hydraulic fracture characterization September 24, 2013
2. slide 2 SEG Houston 2013 Hydraulic Fracture Characterization •  Need to understand: –  Fracture geometry –  Properties of fractured rock –  Production / Injection behavior –  Proppant distribution •  How do we optimize: –  Well spacing? –  Stage spacing? –  Cluster spacing? –  Volume of proppant and fluid? –  Pumping pressures? –  … Figure courtesy of Encana
3. slide 3 SEG Houston 2013 Hydraulic Fracture Characterization •  Need to understand: –  Fracture geometry –  Properties of fractured rock –  Production / Injection behavior –  Proppant distribution •  Need to understand: –  Fracture geometry –  Properties of fractured rock –  Production / Injection behavior –  Proppant distribution Figure courtesy of Encana
4. slide 4 SEG Houston 2013 •  Microseismic •  Tiltmeters •  Pressure Transient Analysis •  Fiber Optics: –  Distributed Acoustic Sensor –  Distributed Temperature Sensor Current Fracture Monitoring Technologies Figure: Cipolla and Wright, 2000
5. slide 5 SEG Houston 2013 Current Fracture Monitoring Technologies •  Logs: –  Temperature –  Production –  Image –  Caliper •  Tracers: –  Radioactive –  Chemical Figure: Barree et al. 2002
6. slide 6 SEG Houston 2013 Current Fracture Monitoring Technologies Figure: Maxwell, 2011 Figure: Cipolla and Wright, 2000 Figure: Barree et al. 2002 Limited information about proppant distribution at reservoir scale
7. slide 7 SEG Houston 2013 How do we map the propped region of a hydraulically fractured reservoir? Objective
8. slide 8 SEG Houston 2013 Using Electromagnetics? •  Requirements: –  Physical property contrast –  Design a survey that generates a measurable response –  Means of inverting and interpreting the data Figure courtesy of Schlumberger
9. slide 9 SEG Houston 2013 Using Electromagnetics? •  Requirements: –  Physical property contrast –  Design a survey that generates a measurable response –  Means of inverting and interpreting the data Figure courtesy of Schlumberger
10. slide 10 SEG Houston 2013 Idea: Create our own Geophysical Target Use electrically conductive or magnetic proppant Physical property contrast Image the contrast using EM
11. slide 11 SEG Houston 2013 Idea: Create our own Geophysical Target Use electrically conductive or magnetic proppant Physical property contrast Image the contrast using EM What does a doped hydraulic fracture look like as a geophysical target?
12. slide 12 SEG Houston 2013 Overview
13. slide 13 SEG Houston 2013 Effective Medium Theory Goal: Assign an effective property that captures the macroscopic response of a material whose properties vary on the microscopic scale
14. slide 14 SEG Houston 2013 Single Inclusion Solutions Inside the Sphere: Inside the Ellipsoid: E = R(2,1)E0 R(2,1) =  1 + 1 3 2 1 1 1 E = e R(2,1)E0 e R(2,1) =  e I + e A2 2 1 1 1
15. slide 15 SEG Houston 2013 Spherical Inclusions e R(j,1) =  e I + e Aj j 1 1 1 R(j,1) =  1 + 1 3 j 1 1 1 Maxwell Approximation Ellipsoidal Inclusions N X j=1 j( ⇤ j)R(j,1) = 0 N X j=1 j(e ⌃⇤ j e I)e R(j,1) = 0
16. slide 16 SEG Houston 2013 Spherical Inclusions e R(j,1) =  e I + e Aj j 1 1 1 R(j,1) =  1 + 1 3 j 1 1 1 Maxwell Approximation Ellipsoidal Inclusions N X j=1 j( ⇤ j)R(j,1) = 0 N X j=1 j(e ⌃⇤ j e I)e R(j,1) = 0
17. slide 17 SEG Houston 2013 e R(j,⇤) = h e I + e Aj e ⌃⇤ 1 ( j e I e ⌃⇤) i 1 N X j=1 j(e ⌃⇤ j e I)e R(j,⇤) = 0 R(j,⇤) =  1 + 1 3 j ⇤ ⇤ 1 N X j=1 j( ⇤ j)R(j,⇤) = 0 Self Consistent Approximation Spherical Inclusions Ellipsoidal Inclusions
18. slide 18 SEG Houston 2013 e R(j,⇤) = h e I + e Aj e ⌃⇤ 1 ( j e I e ⌃⇤) i 1 N X j=1 j(e ⌃⇤ j e I)e R(j,⇤) = 0 R(j,⇤) =  1 + 1 3 j ⇤ ⇤ 1 N X j=1 j( ⇤ j)R(j,⇤) = 0 Self Consistent Approximation Spherical Inclusions Ellipsoidal Inclusions
19. slide 19 SEG Houston 2013 Implementation
20. slide 20 SEG Houston 2013 Effective Conductivity of Fractured Rock Volume Proppant & Fluid Single Stage: -  350,000 lbs proppant -  10 fractures: 2.5mm wide 10 m x y z
21. slide 21 SEG Houston 2013 Effective Conductivity of Proppant & Fluid
22. slide 22 SEG Houston 2013 Effective Conductivity of Proppant & Fluid •  Conductive proppant & fluid •  Self-Consistent Method –  Spherical Inclusions R(j,⇤) =  1 + 1 3 j ⇤ ⇤ 1 N X j=1 j( ⇤ j)R(j,⇤) = 0
23. slide 23 SEG Houston 2013 Effective Conductivity of Proppant & Fluid •  Conductive proppant & fluid •  Self-Consistent Method –  Spherical Inclusions R(j,⇤) =  1 + 1 3 j ⇤ ⇤ 1 N X j=1 j( ⇤ j)R(j,⇤) = 0 2500 S/m
24. slide 24 SEG Houston 2013 Effective Conductivity of Fractured Rock Volume
25. slide 25 SEG Houston 2013 Effective Conductivity of Fractured Rock Volume Proppant & Fluid : 2500 S/m Background: 1e-2 S/m •  Conductive Cracks •  Self Consistent Method –  Inclusion Shape? •  Ellipsoids •  Spheroids –  Form? •  Strong •  Weak e R(j,⇤) = h e I + e Aj e ⌃⇤ 1 ( j e I e ⌃⇤) i 1 N X j=1 j(e ⌃⇤ j e I)e R(j,⇤) = 0
26. slide 26 SEG Houston 2013 Effective Conductivity of Fractured Rock Volume
27. slide 27 SEG Houston 2013 Effective Conductivity of Fractured Rock Volume Proppant & Fluid : 2500 S/m Background: 1e-2 S/m x (m) x y z z (m) y (m) •  5x5x5 m cells •  Spheroidal inclusions –  σ* yy = σ* zz –  σ* xx = 0.01S/m σ* yy model
28. slide 28 SEG Houston 2013 Signal Analysis RX TX: Magnetic Dipole 5000 Am2 d x y z
29. slide 29 SEG Houston 2013 Signal Analysis: Secondary Magnetic Field d = 50m RX Noise Floor: 0.01pT
30. slide 30 SEG Houston 2013 Signal Analysis: Secondary Magnetic Field d = 100m RX Noise Floor: 0.01pT
31. slide 31 SEG Houston 2013 Signal Analysis: Secondary Magnetic Field d = 200m RX Noise Floor: 0.01pT
32. slide 32 SEG Houston 2013 Signal Analysis: Secondary Magnetic Field d = 200m RX Noise Floor: 0.01pT
33. slide 33 SEG Houston 2013 Conclusions •  Using effective medium theory: –  Fracture model à physical property model –  Self Consistent Method – strong form •  Characterizing shape of fractures exactly: not as essential •  Can detect a response •  Next: Forward Model & Survey Design Field Survey Inversion & Data Interpretation
34. slide 34 SEG Houston 2013 •  Thanks to Michael Wilt, Jiuping Chen, Nestor Cuevas and Ping Zhang with the Schlumberger EMI Technology Center for their help and support on this project Acknowledgements
35. slide 35 SEG Houston 2013 Questions? Thank you!
36. slide 36 SEG Houston 2013 •  Berryman, J. G., and G. M. Hoversten, 2013, Modelling electrical conductivity for earth media with macroscopic fluid-filled fractures: Geophysical Prospecting, 471–493. •  Bruggeman, D., 1935, The calculation of various physical constants of heterogeneous substances. i. the dielectric constants and conductivities of mixtures composed of isotropic substances: Ann. Phys, 24, 636–679. •  Choy, T. C., 1999, Effective medium theory: Principles and applications: Oxford Science Publications. •  Cipolla, C., and C. Wright, 2000, Diagnostic techniques to understand hydraulic fracturing: what? why? and how?: Presented at the SPE/CERI Gas Technology Symposium. •  Milton, G., 1984, Correlation of the electromagnetic and elastic properties of composites and microgeometries corresponding with effective medium approximations: AIP Conference Proceedings, 66. •  ——–, 1985, The coherent potential approximation is a realizable effective medium scheme: Communications in mathematical physics, 99, 463–500. •  ——–, 2002, The theory of composites, 1st ed.: Cambridge University Press. Cambridge Monographs on Applied and Computational Mathematics. •  Shafiro, B., and M. Kachanov, 2000, Anisotropic effective conductivity of materials with nonrandomly oriented inclusions of diverse ellipsoidal shapes: Journal of applied physics, 87, 8561–8569. •  Torquato, S., 2002, Random heterogeneous materials: Microstructure and macroscopic properties: Springer. •  Ward, S. H., and G. W. Hohmann, 1988, Ch. 4, in Electromagnetic Methods in Applied Geophysics: Society of Exploration Geophysicists, Vol. 1, 131–311. References
37. slide 37 SEG Houston 2013 Effective Conductivity of Fractured Rock Volume
38. slide 38 SEG Houston 2013 Signal Analysis: Secondary Magnetic Field Real Imaginary