RR#3
Velocity model.
In simplicity siesmic is arrray which records time signal have been sent from source and time signal was red as reflected by probe.
So the physics is following - two media with different density will reflect back energy while wave will pass border of this two media .
So this border will give you time signal travel to and reflect from . So time is double.
Since we live in world where 3 dimention is lenth we need to transform the time to depth.
This can be done by several ways the easiest is to make interval model where you assign for each interval velocity
Let say you have 2 horizons
first one have T1 - time surface , Z1 - depth surface
Second have T2 - time surface , Z2 - depth surface
So you will need to build 2 interval model
Fo interval 0 to Z1 you velocity model will be described as
V1=(Z1/T1)*2000
For second interval from Z1 to Z2 your velocity model will be described as
V2=((Z2-Z1)/(T2-T1))*2000
And so on
You can use this rule with checkshots also
Regards