Geophysicks

Most of the old  seismic data archive that exists today available  only in the of hardcopy format. The tapes that contained the data have mostly are lost, unreadable or not available for some other reason. Seismic Vectorizing or Seismic Reconstruction is a process that convert seismic data from hardcopy (seismic paper) to softcopy or standard digital format i.e. SEGY format

Different seismic vectorization algorithms are used depend on the quality of the original image.  Several post-stack processing can be applied to enhance the data quality of the original processing by using different processing modules and output to SEG-Y.

Reprocessing and enhancement of 2D post stack seismic data can be applied (either derived from scanning or from existing digital data), such as:

Band pass filtering
Trace scaling (AGC or TV scale)
Deconvolution
Trace Mix
Noise attenuation (FXDECON)
FK- filtering
Trace interpolation
Trace editing and shot point insert
Migration

Vectorizing result overlaid on the original image

 

The data preconditioning is one of key process to output a good seismic vectorizing result. Any interpretation , sketch , mark , fold mark should be eleminated before conversion.  One way to see the vectorizing result is overlying the seismic vectorizing result on the original image. Note on the image above that the result fits on every seismic event and the interpretation is eleminated.

 

 

 

Three component VSP (Vertical Seismic Profiling) consist of X component , Y component and Z component. The three component are rotated to obtain pure direct, perpendicular, and transverse component.

Normal stress
The component perpendicular to the wavefront plane is termed normal stress.
The receiver recieves this signal as direct component which is compresional wave.

Shear stress
The component parallel to the wavefront plane is termed shear stress.
The receiver recieves this signal as perpendicular component which is shear wave.

 

To obtain the direct wave and shear wave, rotation is done twice.

Horizontal Rotation
Horizontal components are rotated thus one component receives maximum response while the other one receives the minimum one.

Vertical Rotation
Vertical rotation is done thus one component recieves maximum response while the other one receives the minimum one.

 

Following is flash illustration to help understand the VSP component better

 

or you can view it bigger here

 

In seismic, there are two kind of resolution. vertical resolution (temporal) and lateral resolution (spatial).

Vertical resolution is defined as ¼ seismic wavelength ( λ ), where λ= v/ f , v is sonic wave velocity and f is frequency, where usually dominant frequency (fdom) is used.

image courtesy of http://ensiklopediseismik.blogspot.com

if fdom 25 Hz velocity 2500m/s then the minimum thickness that can be separated on seismic is  25 meter

To separate thin layer below seismic resolution, we can restore atenuated high frequency using  high frequency restoration method using VSP data.If the VSP data is unavailable, we still can boost up high frequency using  high frequency enhancement.

Well resolution is far above seismic resolution. This would become a problem when we want to do well seismic tie especially on thin layer beyond seismic resolution. Some trick to tie over the problem is lowering the well frequency or restoring / enhancing seismic high frequency. Restoreing / enhancing seismic high frequency is prefered since no data is eleminated / reduced thus we can preserve the information contained.

Seismic High Frequency Enhancement. Note the dominan frequency on the amplitude spectrum after enhancement slide over 40 Hz

 

Seismic section before and after High Frequency Enhancement. note the thin layer separation.

 

Seismic section before and after High Frequency Enhancement and post-stack enhancement. note the thin layer separation and reflector continuity are both enhanced.

bahasa simple nya ya gan, maap kalo rada ngawur

petroleum dibagi menjadi:
1. GnG alias geology and geophysics
tahap eksplorasi dari migas. geologist mencari potensi sumber minyak berdasarkan sejarah pengendapan “tanah” secara regional. lalu geophysicist mencari lebih detail detail kondisi bawah permukaan dan potensi nya dengan metoda seismik (prinsipnya seperti sonar. kebayang kan?).
itulah mengapa kami disebut anak “underground"…. kebanyakan kami pake sepatu boot underground (baca:safety shoes )…
kalau sedang picking horizon kami pun pasti nyetel lagu underground dan metal
2. drilling engineering
setelah anak anak underground merekomendasikan lokasi potensial, anak anak perguruan inul daranista ngebor di lokasi itu.
mengambil sampel batuan di bawah permukaan, melakukan logging (pengukuran properti batuan di bawah sana. ) dsb
3. formation evaluation / petrophysics
dari data property/ sifat fisis batuan bawah permukaan yang diberikan anak anak perguruan inul daranista tadi, petrophysicist mengevaluasi interval lapisan dibawah sana yang mana saja yang potensial untuk produksi minyak dan atau gas bumi.
4. reservoir engineering
setelah dianalisa lapisan mana saja yang diperkirakan potensial, reservoir engineer mengkalkulasi jumlah cadangan minyak bumi lalu melakukan simulasi berdasarkan data sifat fisis / property batuan yang diberikan petrophysicist.
dari hasil simulasi didapat jumlah minyak bumi dan atau gas yang dapat diambil, berapa produksi per hari, sampai kapan lapangan tersebut bisa memproduksi minyak bumi, dsb
5. production engineering
bagian ini menghandle urusan produksi minyak bumi. mulai dari bikin fasilitas produksi, produksi itu sendiri, penampungan minyak, pengolahan minyak, fasilitas pengolahan limbah, sampe pengangkutan minyak ke penampungan milik pertamina yang gede itu.

naahhhh…
kira kira bahasa simple nya seperti itu…
mudah mudahan bisa memberikan pencerahan…


salam…

A good seismic vectorizing result would match the original image, either in dimension accuracy (i.e. peak trace position and time position), or amplitude accuracy (bright-dim contrast). Most other vectorizing process produce SEGY file with those error, either SEGY image don't perfectly match the original image, or the dim and bright amplitude have nearly equal value. Usually the bright amplitude on the SEGY result is not as bright as the original image.

Following are my vectorizing result, click on the image to view larger image.

Original image vs SEGY result

We can see the quality of the Seismic Vectorizing process by overlying the SEGY result on the original image. Thus we can see the accuracy of the conversion process either in the dimension or the amplitude.

 

SEGY wiggle result overlaid on original image

SEGY grayscale result overlaid on original image

 

Following are another results of Seismic vectorizing / Seismic Reconstruction. Note that the the interpretation mark, the horizon pick, and fault pick, are removed and disapear on the SEGY result.

Original image, note the interpretation mark

SEGY wiggle result overlaid on original image

SEGY wiggle result zoom overlaid on original image, note that the interpretaion mark disapeared

 

Some post-enhancement can be applied to give better quality on seismic data. It makes the interpretation easier since the reflector / event continuity is enhanced. Following are the enhancement result example, click on the image to view larger image .

 

 

 

I can do High Quality Seismic Vectorizing (Seismic Reconstruction / conversion)  for cheap price. You can compare the quality among other top service company and I can give better or at least same quality for cheaper price.

I can give you testline for free to assure you the quality of my conversion.

 

p.s. do NOT use this content especially the image for commercial use. You can use for your site (put the link to my site on your site), use or save the content for educational use and personal use only.