Page 99 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

Formation Evaluation 87

30

25

20

15

0 20 40 60 80 100
FRACTIONAL OIL WETTABILITY */o

1" 1 1 1 1 1 1 I
I00 80 60 40 20 0

FRACTIONAL WATER WETTABILITY, O&,
Figure 5-61. Influence of wettability on saturation exponent [179].

texture of petroleum reservoirs. Table 5-20 [180] lists the types of analyses that
are obtained and how the results of each analysis are used. Specialized core
analyses, such as are listed in Table 5-21, are done less often, but are important
for specific applications. Routine core analyses can be performed on whole cores
or on small plugs that are cut from a larger core. With the exception of
petrographic analyses (thin sections, x-ray; scanning electron microscopy, etc.),
special core andyses are normally done with core plugs. After a well is drilled
and logs are available to identify zones of interest, very small portions of the
reservoir can be obtained with percussion sidewall or sidewall drilled cores.
Sidewall cores are less expensive and are valuable for petrographic analyses, but
are generally not suitable for special core analyses.
The subject of coring and core analysis was summarized recently in a series
of articles [181-1891. An overview article [190] described how core analyses can
aid reservoir description. A handbook [191] is available that describes procedures
and tools for conventional coring as well as methods for routine core analysis.
Procedures for routine core analysis and methods of preserving cores have been