Page 113 - Well Logging and Formation Evaluation

CHAPTER 6

INTEGRATION

WITH SEISMIC

While one part of petrophysics is concerned with the interface with geol-
ogists and reservoir engineers in order to produce reservoir models, a
further interface exists with the seismologists to ensure that the well data
are used to help calibrate and understand seismic properties.
While the preparation of synthetic seismograms to tie log-formation
tops with seismic horizons is a long-established technique, recent ad-
vances in far-offset seismic processing, combined with the ability to
measure shear-sonic transit times, have opened up a lot of new possibili-
ties for facies and fluid determination from seismic data. In this chapter
some of these techniques will be discussed.

6.1 SYNTHETIC SEISMOGRAMS

There are two elements to synthetic seismograms. The first is the der-
ivation of the acoustic impedance (AI) from the log data, from which
reflectivity may be derived. The second is the conversion of the depth-
related traces from a depth reference to a time reference so they can be
compared with seismic sections. From the log data, the following may be
derived:

V p = 1 6 (3 281 sonic, * ) (6.1.1)
e
where V p is in m/s and sonic is measured in ms/ft.

r= 1e6*density (6.1.2)

3
where r is in kg/m and density is measured in g/cc.

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