Page 59 - Well Logging and Formation Evaluation

CHAPTER 3

FULL INTERPRETATION

The quicklook analyses presented in Chapter 2 will be sufficient for oper-
ational decisions on the well. Usually the results are presented by making
a clear print of the evaluated logs at scales of 1:200 and 1:500 with the
sums and averages marked on the logs and the porefluids marked using
appropriate colors. All companies will use blue for water, but some prefer
red for oil and green for gas, while others prefer red for gas and green for
oil.
Once the final data and prints have been received from the logging
contractor, the digital data should be stored within a corporate database.
Normally at this point the petrophysicist will do a full interpretation,
which might be revised as further core analysis or information from offset
wells becomes available.
In some cases the quicklook Archie model might be completely set
aside in favor of a more advanced model, as described later in this book.
In other cases it is sufficient merely to refine the conventional Archie
interpretation. In this chapter the ways the Archie model may be refined
will be discussed.
3.1 NET SAND DEFINITION

If core data have been acquired, it is essential that the petrophysicist
pay a visit to the core shed at the earliest opportunity to inspect the slabbed
core. This will provide a check that there are not anomalous zones that
have been wrongly allocated to reservoir or nonreservoir status in the
interpretation. Where reservoir can be easily identified, one should make
measurements of the core to ascertain the exact net sand footage that can
be checked against the calculations made on the logs.

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