07_oil_and_gas_industry_simulations.tex

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\chapter{Oil and gas industry simulations}

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The SPECFEM2D package provides compatibility with industrial (oil and gas industry) types of simulations.
These features include importing Seismic Unix (SU) format wavespeed models into SPECFEM2D,
output of seismograms in SU format with a few key parameters defined in the trace headers
and reading adjoint sources in SU format etc.
There is one example given in \texttt{EXAMPLES/INDUSTRIAL\_FORMAT}, which you can follow.

We also changed the relationship between adjoint potential and adjoint displacement in fluid region
(the relationship between forward potential and forward displacement remains the same as previously defined).
The new definition is critical when there are adjoint sources (in other words, receivers) in the acoustic domain,
and is the direct consequence of the optimization problem.
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\begin{align*}
\mathbf{s} &\equiv \frac{1}{\rho} \: \mathbf{\nabla}\phi \\
p &\equiv -\kappa\left(\nabla\cdot\mathbf{s}\right) = -\partial_t^2\phi \\
&\\
\partial_t^2\mathbf{s}^\dagger &\equiv -\frac{1}{\rho} \: \mathbf{\nabla}\phi^\dagger \\
p^\dagger &\equiv -\kappa\left(\nabla\cdot\mathbf{s}^\dagger\right) = \phi^\dagger
\end{align*}