deletions | additions       diff --git a/velocity results.tex b/velocity results.tex  index 1fbc57d..553d995 100644  --- a/velocity results.tex  +++ b/velocity results.tex 
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\subsubsection{Velocity}  The injection of CO$_2$ causes a fluid substituion within the pore space. For fluid susbstitution with no change in matrix properties, a change in P-wave velocity is expected due to the change in bulk modulus (compressibility) with a minimal change in S-wave velocity expected due to the lack of change in shear modulus (which is a properties not affected by pore fluid).  P-wave velcities (Fig. \ref{fig:fig}4a \ref{fig:fig4}a  - left) show an intial decrase in the pore pressure range 2-7 MPa for all runs and the two samples. This is consistent with the CO$_2$ velocity beahviour (Fig. \ref{fig:fig3}) where the lower velocities are registered around the critical point when the CO$_2$ is a supercritical fluid (7.5 MPa and 31.8 $^{\circ}$C). Once crossed the phase transition, velocities increase with pore pressure for both runs. This trend is far more evident for the CH sample rather than the CA sample. The almost lack of S-wave velocity changes confirms that the observed P-wave change is caused by fluid substitution of gaseous CO$_2$ to liquid/supercritical CO$_2$.\\