reverse time migration for wave equation PDE using SBP-SAT
I have no experience with SBP-SAT methods, but you may try and go through the references in (and potentially contact the authors of) this paper https://arxiv.org/pdf/1802.06123.pdf .

Personally, I don't see a strict need for using such 'complicated' modelling methods for RTM. In the ideal case, you have deghosted (i.e., upgoing) recorded data and a smooth velocity model. Then, using standard low-order finite-difference modelling on a uniform grid should already provide fairly good results at fairly little cost. Likely, you'll achieve better results by optimizing the data &amp; velocity model than improving your numerical code beyond the standards. This simple MATLAB code https://csim.kaust.edu.sa/files/ErSE328.2013/LAB/WE_LABS/index.html already does a brilliant job using 2nd order accuracy in time and 8th order accuracy in space, using a simple FD method.

Of course, if you are doing state-of-the-art (academic) research or are dealing with a very atypical velocity model with an extreme dynamic range, these are interesting topics to look into, and I hope that someone may be able to help you... But I hope that my answer may help you right now.