BDAT

Not all refraction data are shot with a source on the surface of the ground, and the ground is not always flat. BDAT can shift data by static shifts to datum the data to the shot elevation. This program is often used with buried explosive shots. The up-hole time can provide a value for the overburden velocity.

   bdat  infile vel iapply
 
     infile   =  input file name
     vel      =  velocity of overburden
     iapply   =  switch
             1=  apply static to datum 
            -1=  remove static, restore to observed 
 
 NOTES: 1 Statics are computed from geometry in headers.  
         The receiver is datumed to the shot elevation. 
 
        2 Intended use is to make recognition of first  
         arrivals easier, and picking easier.
 
        3 First break pick headers are adjusted with 
         each datum change

BDAT uses a weathering zone approach, and computes the static shift using the header values:

• sz Shot elevation (top of hole if buried)
• sd Shot depth
• rz Geophone elevation

The static shift is computed as:

$$T_s = \dfrac{(sz-sd-rz)}{vw}$$ (9)

where $vw$ is the weathering velocity.