Rebellion on status Quo, challenging the presence of comfort zone, being back in youth time, where it’s only you, and what you want to do is the only thing matters. Nothing about mortgage payment, nothing about the dignity of your social status, nothing really matters except what is it maters at that time. Impulsive!
Excitement of youth time. But the time never moves backward. Hello Captain Obvious!
and then time would said, “Where were you at that time?”
A good friend of mine (Sunawar Kunaifi) showed me his script on VSP (borehole seismic) processing with SeismicUnix (CWP, Colorado Schol of Mines), we exchanged email back and forth, and discussion with him was very good and very enlightening, so that I can come up with a set of script to do VSP modeling and VSP processing, for the basic and simple VSP data. The VSP tutorial from EnsiklopediSeismik.blogspot.com is also very helpful, so my scripts is kind like wrap things up that has not yet been covered by that tutorial.
I set up an information page here LatihanVSPSU (http://www.gm2001.net/latihanvspsu/). I also start to learn and begin to like Git, I use github as my code repository, visit http://www.github.com/fahdi104/LatihanVSPSU.
Synthetic modeling is not using SeismicUnix though, since I can’t find a way or understand which SU program that can do elastic modeling using certain geometry. I’m using Ela2D from Joachim Falk (University of Hamburg) for elastic synthetic modeling.
The script is still far away from perfect. If I processed the synthetic data, the results looks weird, and also in real dataset. I mean weird in terms of looks like the amplitude data is clipped/distorted. The other thing is I couldn’t find a good deconvolution to be applied with the data. Of course Seismic Unix has this predictive error filtering/predictive deconvolution module, but my exercise shown the result is not that good.
If you have sometimes, maybe you can see my scripts, and give some suggestion to me.
Kemana mencari warna? dalam tebaran krayon-krayon yang menemani anak-anak kecil itu? atau pada cat minyak para seniman?
Kemana mencari rasa? dalam tiap takaran rempah para pandai boga? atau pada akar rempah itu sendiri?
Kemana mencari masa? dalam detak-detik jam yang berputar mengelilingi poros selama enam puluh menit? atau pada matahari yang menjadi pusat atas bimasakti?
Bagaimana bertemu makna? apakah harus melihat warna mengecap rasa pada satu masa?
Ketika mata tak melihat warna, ketika lidah tak mengecap rasa, ketika masa pun berlalu tanpa menghiraukan kita.
Apakah kemudian kita tidak bertemu dengan makna?
Continuing my previous post about Idea for Geophysics Project?, I’d like to write down whats has been going around inside my head few weeks back. Though, the are no progress at all regarding those 2 previous projects that I wrote, but hey, maybe somebody stumbled upon my blog and then get inspired 
HAHAHAHA.
Anyway, this project still about Borehole Seismic (VSP), because I was stuck with this stuff recently. Lets summarize it then,
Sometimes, even in parametric wavefield decomposition was done in frequency domain. If there is any aliasing in the data, this will make issues in wavefield separation. Jovanovic summarize this in her thesis in Univ. of Houston (P SV Polarization Filtering), and publish this in SEG (2004). Though I think if the moveout between even are still close, even radon domain cannot separate it clearly, but high resolution radon might help to separate this.
I faced sometimes in Indonesia VSP data, wavefield separation of VSP data cannot be done easily. The shear wave contamination in compressional wavefield cannot easily be separated. To my understanding it can be because due to aliasing or something else, so that maybe high resolution radon can help with this.
The field of interferometric is really growing right now. Especially in utilizing VSP multiple for imaging, some are using VSP downgoing wavefield for imaging, and some are using VSP ghost multiple. One thing that is really improvement of using multiple migration is to make VSP image wider using ghost multiple just like the one that is summarized by Zhiyong Jiang et al (TLE, 2004 or Min Lou (SPG India, 2008). As we all know, VSP is lacking of illumination, low/narrow fold coverage, narrow aperture. This VSP multiple can help to overcome the situation. My expectation was just at least I have some improvement in edge reflection image of VSP migration result.
Min Lou (SPG India, 2008) summarized steps that are required to do this imaging. When I red his paper, I was thinking a short way to do it. They summarized about mirror imaging, how you mirror your velocity model above the free surface, and put your receiver in the mirror velocity model. I was thinking by mirroring this, when you doing raytracing, you can raytrace your multiple reflection in the same reflection plane as your primary reflection. Thus, without doing any numerical programming, I can do VSP multiple migration just by make mirror velocity model 
I haven’t tried, but is this what the paper said?
Too bad, because we are using ghost multiple, this method may not be applicable for land data, where in Indonesia VSP in onshore is more acquired than offshore. Even in the offshore, I think it is required that the water coloumn is thick enough to generate some multiple. But I think this multiple imaging is promising.
That’s all folks, hope I can do something with the Idea
* fiuhhh, my English is so bad 
I think I should write these ideas, while these things still running around inside my head. Though, again this idea might seems impossible to be done, hehehe
1. Anisotropic based on Shear Wave Splitting analysis on Zero Offset VSP.
There were several attempts on this one. Internally and also externally outside my current company. What I have red so far about fast shear and slow shear extraction using parametric wavefield decompositions (Parametric wavefield decomposition and applications, Leaney et al, 1990 ).
But today, I read a recent paper from Curtin Univ group, they attempted to run semblance-wise analysis to extract shear wave splitting. My understanding as of now regarding this paper are,
a. You project your horizontal component to several azimuth,
b. Using the projected horizontal component, you run semblance analysis for multicomponent linear traveltime moveout velocity analysis. The main idea is to estimate the dominant apparent velocity for a given polarization direction by measuring the coherency of the seismic signal of a large number of events as a function of the apparent velocity. So, this look like semblance analysis on the presence of a large number of shear wave events with the same apparent velocity.
Usually and ideally, we will need multi offset walkaround VSP in order to properly measured anisotropic parametr based on shear splitting phenomenon. But this paper reported that their attempt can be done by analyzing many low-amplitude PS mode converted waves on zero offset VSP.
To me this is doable, since projection and semblance is available within our current software. But lets see whether this is really doable or not.
Detail of the methods can be seen in this paper, Estimation of azimuthal anisotropy from VSP data using multicomponent S-wave velocity analysis, 2011
2. Full waveforms inversion of VSP data
This is a very optimistic idea As of now, the full waveforms inversion is regarded as one of the best solution to image complex structures. But the idea of inverting the whole waveforms of VSP data in this project is just to approximate higher velocity field information. Because normally, what we invert from VSP data is just the traveltime, which yields lower frequency information.
Why this is doable a lot of forward modeling code is available for research purposes (SeismicUnix, Crewes, SOFI, etc). Lets forget about the sophisticated method of iterative solver, frequency domain modeling etc etc. Lets just use what is available for the forward modeling, and focus on the inversion.
Lets try it with local optimization approach, and then maybe if I suddenly I struck by lightning and become a genius, we can try to run the global optimization approach for the inversion.
The guide paper for this is Nonlinear Inversion of Seismic Waveforms, by Marwan Charara, Christophe Barnes and Albert Tarantola.
Anybody care to share their thoughts on my project?
