Page 184 - Petrophysics

PERMEABILITY-POROSITY RELATIONSHIPS 157

Horizontal Perm. Vertical Perm.
mD mD
io 0.i i io io0 iaoo ioooo

-Log Data for Total Shale
- LogData Core Data

Figure 3.43. Core- and log-derivedpermeability for the TAGI formation [46].

where kH and kv are in millidarcies, Q is the effective porosity (fraction),
and dgr is in cm. Figure 3.43 shows an acceptable match of k, and kH
values obtained from well logs and core measurements.
All the above correlations relating vertical permeability to horizontal
permeability have a strong physical meaning in the sense that they depict
the degree of anisotropy, expressed by equation 3.96, in a formation
containing various types of shale. This is very critical to the efficient field
development and productivity of the formation.

EXAMPLE

Core analysis in a new well in the TAGI formation revealed a
horizontal permeability of 0.58 mD. Assuming that the TAGI is an
equal Kaolinite-Illite formation, estimate the vertical permeability and
anisotropy ratio for this well using the models developed for this
formation for the following cases:

(a) Only horizontal permeability is known.