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Modular electromagnetic simulations with applic...

Modular electromagnetic simulations with applications to steel cased wells

Interest in using electromagnetic methods for reservoir monitoring problems such as hydraulic fracturing, en- hanced oil recovery or carbon-capture and storage is motivating the need to examine the behaviour of electro- magnetic fields and fluxes in the presence of steel cased wells. In many of these scenarios, a transmitter is placed on or in the steel cased well. Such a scenario has large physical property contrasts, both in electrical conduc- tivity and magnetic permeability that are atypical of most geologic settings. Using this problem as motivation, we discuss a modular framework for simulating and computing sensitivities for electromagnetic problems. The implementation is a part of SimPEG, an open source package for Simulation and Parameter Estimation in Geophysics (Cockett et al., 2015). Two applications of EM simulations and inversions in reservoir monitoring settings are discussed. The first example demonstrates forward simulations on a cylindrically symmetric mesh to interrogate and visualize electromagnetic fields and fluxes in the presence of steel cased wells. The second example demonstrates a sensitivity analysis for a parametric model of a target within a reservoir layer.

Extended abstract available at: http://nebula.wsimg.com/d08e4f75db1a3988252f35a74b79db9d?AccessKeyId=C1B15BD8D0A222F3993D&disposition=0&alloworigin=1

Lindsey Heagy

March 30, 2017
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  1. Modular electromagnetic simulations with applications to steel cased wells Lindsey

    Heagy, Rowan Cockett, Doug Oldenburg & the SimPEG team Geophysical Inversion Facility University of British Columbia
  2. building for researchers • Flexibility to experiment ◦ Prioritize organization

    and flexibility • Integration of information ◦ Geologic ◦ Multiple physics • Reproducible and transparent
  3. • Modular: building blocks ◦ organized in a framework ◦

    pieces available to manipulation • Declarative: express intent ◦ write what you mean ◦ looks like the math • Extensible: new research ◦ quantitative communication ◦ built in feedback loops • Open: for the future ◦ reproducible ◦ opportunities for collaboration building for researchers
  4. building for researchers • Modular: building blocks ◦ organized in

    a framework ◦ pieces available to manipulation • Declarative: express intent ◦ write what you mean ◦ looks like the math • Extensible: new research ◦ quantitative communication ◦ built in feedback loops • Open: for the future ◦ reproducible ◦ opportunities for collaboration
  5. em + steel casing This is a problem. Want to

    characterize this (SEG Abstract: Heagy et al, 2015) Physical Properties • highly conductive • significant (variable) magnetic permeability Geometry • cylindrical • thin compared to length
  6. • Fields magnetic flux density current density • Physical Properties

    • Fluxes Constitutive Relations Maxwell’s Equations (quasi-static) electric field magnetic field electrical conductivity magnetic permeability Time Frequency math!
  7. ?

  8. Model & Physical Properties: What should we invert for? (SEG

    Abstract: Kang et al, 2015) Derivatives using chain rule: or : • Active reservoir layer • Parametric representation • ... inversion model physical properties
  9. ?

  10. grounded electric inductive loop point dipole (electric or magnetic) fields

    from a primary problem natural source Sources: How do we excite the Earth?
  11. ?

  12. Solve 2nd order system Solve E-B, H-J ? or and

    compute derivative Physics: How do we solve Maxwell’s equations
  13. ?

  14. compute fields everywhere: what we solved for from source derivative

    Fields: How do we calculate the EM fields and fluxes? from source from physics
  15. ?

  16. for example: casing & sensitivities What is the sensitivity with

    respect to the… • conductivity of the ◦ Block? ◦ Layer? ◦ Background? • Depth and thickness of the layer? • Location and widths of the block? Heagy et al. 2017 - in review
  17. summary • Modular, composable pieces ◦ Compartmentalize concerns ◦ All

    pieces available to manipulation ◦ extensible • Testing! ◦ Test pieces ◦ Test composite http://www.flickr.com/photos/13403905@N03/2080281038/