Print this pageAbstract: Geological
Controls on 
Permeability
Distribution and Sand Distribution: Tar Zone,
Fault Block IIA, Wilmington Field
DAVIES, DAVID K., and RICHARD K. VESSELL
Lateral and vertical
variations of reservoir quality in turbidite sandstones of the Tar Zone
(T and D intervals) are controlled principally by original rock texture
(specifically grain size and sorting) and diagenesis (specifically compaction).
Interaction of these factors has resulted in variable pore geometries.
Quantification of pore geometrical attributes allows for identification
of 4 sandstone rock types: intervals of rock with similar pore geometry,
porosity-permeability relationships, and capillary pressure characteristics.
Permeabilities range over several
orders of magnitude for any given value of porosity. Accurate prediction
of permeability requires a knowledge of both rock type and porosity. Algorithms
have been developed (using core measured data) that allow for prediction
of permeability from
a knowledge of rock type and porosity. Individual
rock types can be identified using a standard wireline log suite (SP, GR,
Resistivity, Density, Neutron) - no new logs, no specialized logs are required.
Net footage of each rock type can be determined for each well location
and zone. This allows for rapid computer-based mapping of the distribution
of each Rock Type across the field. There is a close relationship between
depositional environment and rock type distribution. Thus maps of rock
type distribution can be used to illustrate the lateral and vertical variations
in depositional environments.
Search and Discovery Article #90945©1997 AAPG Pacific Section Meeting, Bakersfield, California