#  > Petroleum Industry Zone >  > Geology & Exploration >  >  >  PSTM vs. PSDM

## obama

Can any one tell me what is difference between pstm and psdm?
Thanks,


 :Confused: See More: PSTM vs. PSDM

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## ashok

Hi,
   PSTM stands for pre stack time migration and PSDM stands for pre stack Depth migration.

PSDM is done after PSTM, if there is more complex lateral variation velocity eg presence of salt bodies, complex tectonics, steep dips etc.

There is one more difference between PSTM and PSDM, PSDM is more interpretative processing because it requires a good geologically plausible velocity model(more like inversion)
bye

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## obama

> Hi,
>    PSTM stands for pre stack time migration and PSDM stands for pre stack Depth migration.
> 
> PSDM is done after PSTM, if there is more complex lateral variation velocity eg presence of salt bodies, complex tectonics, steep dips etc.
> 
> There is one more difference between PSTM and PSDM, PSDM is more interpretative processing because it requires a good geologically plausible velocity model(more like inversion)
> bye



Thank you very much for fast reply. So in term of processing sequences there is no difference between PSTM and PSDM. but the velocity model of PSDM is much more details and build specificly for the complex area. is that correct ? Please correct me.

Regards,

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## ashok

> Thank you very much for fast reply. So in term of processing sequences there is no difference between PSTM and PSDM. but the velocity model of PSDM is much more details and build specificly for the complex area. is that correct ? Please correct me.
> 
> Regards,



In terms of processing sequence, PSDM is performed after PSTM, and PSTM follows different algorithm than PSTM, it is also computer intensive,the velocity and the data o/p is of higher quality in areas where you expect lateral variations in velocity.

So, PSDM is not routinely done as it is expensive bcoz it requires lot of computing power.

bye

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## zarei

could anyone share some tutorial about psdm processing using promax?

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## promax.landmark

Any tutrorial about psdm???

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## Mahavir Singh Bidawat

Have you any software regarding geological modelling and pertrophysical analysis, if you have plz tell to me i need this software.

Regards
Mahavir

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## naeemsardar

PSDM results are hardly representative of ture geology espicially in case of highly complex tectonic. Sudden velocity variation some time mislead the PSDM results. Our practical experience of Tectonically complex area of Paskistan told PSTM always yield good results.

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