Go to:

  previous
  next
  story

The Geophysical Corner is a regular column in the EXPLORER, produced cooperatively by the AAPG Geophysical Integration and SEG Interpretation committees, and edited by M. Ray Thomasson. This month's column is titled "VSP -- The Link Between Geology and Geophysics."

VSP Links Geology, Geophysics

By RONALD C. HINDS and RICHARD KUZMISKI

Editor's note: Hinds is a senior geophysicist for PanCanadian Resources, Calgary, Canada; Kuzmiski is responsible for VSP and acoustic log processing at Computalog, Calgary.

Click on the figure below to view greater detail.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 4. On a zero- or near-offset VSP, the upgoing reflected event travels down to the reflecting interface and up to the sonde containing the geophones. If the raypath had continued to the surface along the additional blue line, the event would be in two-way traveltime. The traveltime along the blue path is the first break time for zero-offset geometry. By adding this time to the trace recorded at the sonde, the VSP data is placed into pseudo two-way traveltime.