Lindsey Heagy
Jul 17, 2018 · 2 min read

This week in SimPEG…

Lindsey Heagy: I have been working on writing up some of the early PhD work I did on estimating the conductivity of a fractured volume of rock for a fracture operation with an electrically conductive proppant (particles used to keep the fractures open) and fluid. We approach it in 2 steps: (1) estimate the effective conductivity of a mixture of proppant and fluid, (2) estimate the (isotropic or anisotropic) conductivity of a fractured volume of rock filled with the conductive mixture. For both steps, we use self-consistent effective medium theory (which is now implemented as a Map in SimPEG… see: https://github.com/simpeg/simpeg/pull/706).

From there, we run a simple cross-well experiment on the cylindrically symmetric mesh (ignoring any steel casing) to see if the signal due to the fracture is detectable. The data plots show the secondary magnetic field for a range of source-receiver combinations for a survey conducted at 100Hz. Values below the noise floor of 10^-4 nT are not displayed. The semi-transparent overlay indicates the value of the secondary field as a percentage of the primary field: dark gray is 0–2%, white is 8–10%, and anything above 10% displays as fully transparent (e.g. if it is colored and fully transparent, we are confident we can detect the signal due to the fracture).

The notebooks used to generate these figures are available at: https://github.com/simpeg-research/heagy-2018-fracture-physprops.

SEOGI KANG has been working on a Linear inversion app to illustrate the fundamentals of (geophysical) linear inverse problems (e.g. non-uniqueness, misfit, priori information). The forward kernels consist of decaying oscillatory function, which imitates EM kernel (or EM green’s function). Further, this app allows users to explore some of the important parameters involved in a SimPEG inversion.

New releases

discretize 0.2.1 has been released as has SimPEG 0.9.0. This includes a 3D cylindrical mesh. Check out the release notes here:

To upgrade:

pip install --upgrade SimPEG

At the meeting last week…

We discussed the community repository including a code of conduct, steps for creating a new repository, and contributor guidelines (see #3)

simpeg

Simulation and parameter estimation in geophysics

Lindsey Heagy

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simpeg

simpeg

Simulation and parameter estimation in geophysics

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