Page 123 - Well Logging and Formation Evaluation

Integration with Seismic 113

It is possible to use fuzzy logic in the same way as with AI to also gen-
erate membership functions for various facies as a function of their EI
distributions.
Hence, in the example above, it might be possible to discriminate the
sands from the shales (irrespective of porefill) using the EI. Having dis-
criminated the sands, the AI might be used to discriminate the different
porefills. It should, of course, be remembered that one is still limited by
the quality and resolution of the seismic. Nevertheless, in some fields,
AVO techniques have provided very useful information that has led to the
discovery of hydrocarbons.

Exercise 6.3. Acoustic Impedance Modeling

1. Compare the AI response in the oil leg with the AI response expected
if the sand were water bearing and with that from the overlying shales.
2. Do you consider it likely that you could distinguish between sand
and shale from the seismic? Between oil- and water-bearing sands?
Explain.