|
Crain's Usage Rules For Permeability MethoDS
The methods shown on other pages of this Handbook provide
numerous independent approaches
for calculating
permeability, as well as a number of correction factors
which could be applied. If no reconciliation can be made
between alternative models, discard
the least trustworthy results. In order of preference, it
is suggested you use:
BEST METHODS
1. Permeability
from Porosity Model
Use in sands, shaly sands, carbonates when permeability
regression versus porosity is good to excellent. Results
automatically calibrated to core.
2. Permeability from Porosity
and Water Saturation - Wyllie-Rose and Timur Models
Use in sands, shaly sands, carbonates. Adjust parameters to
obtain match to core.
3.
Permeability from Porosity and
Water Saturation - Lucia Model
Best model for carbonates. Adjust parameters to obtain match
to core.
Other
METHODS
4.
Permeability from Porosity -
Domanoir and Coatwa Models
Use in sands, shaly sands only. Adjust parameters to obtain
match to core.
5.
Permeability from Stonley Wave
Model
Rarely used due to lack of data.
Special Cases
6. Fracture Permeability
Requires fracture
aperture data from resistivity image log.
TRIMming
Permeability
RESULTS
Porosity and water saturation must be trimmed before use in
permeability equations.
Trims may be needed to remove results
above 2000 mD before display or use in other calculations, for
example:
1: PERMw = Min(2000, PERMw)
Fracture permeability may exceed 50,000 mD but such high
values should be confirmed by pressure transient analysis.
|
