Petrophysical
Characteristics and Facies Distribution of Reservoir and Non-reservoir Rocks
from the
Cranganu, Constantin1, Maria
A. Villa2 (1) Brooklyn College of the City University of New York,
Brooklyn, NY (2) Occidental Petroleum Corporation (OXY), Colombia, Bogota,
Colombia
Using mercury intrusion porosimetry
technique we analyzed 103 samples taken from the reservoir and non-reservoir
rocks of the Anadarko Basin, Oklahoma. The samples are mainly sandstones,
shales, and carbonates, ranging in age from Devonian to Permian and in depth
from 404 m to 4,975 m. The objectives of this research are to (1) develop a
classification of capillary-pressure curves; (2) establish criteria for
identifying petrophysical facies based on capillary-pressure curves; and (3)
assess the facies distribution of reservoir and non-reservoir rocks.
The petrophysical parameters used in this
study are: median pore throat radius, average pore throat radius, bulk density,
apparent skeletal density, apparent porosity, maximum threshold-entry radius
(MTER), displacement pressure, entry pressure, pore throat size distribution,
pore throat type, and pore throat sorting (PTS). In addition,
capillary-pressure curves are classified into six categories based on their
shape. The quality of reservoir rocks was estimated using a
permeability/porosity plot. Finally, statistical analysis was used to assess
correlations between various petrophysical parameters.
The main results are: for reservoir
rocks, 38 samples have unimodal pore throat size distribution, 21 samples have
bimodal distribution, and 4 do not exhibit any mode distribution; for
non-reservoir rocks, 19 samples have unimodal distribution and 21 samples have
bimodal distribution. PTS varies between moderate and poor for the reservoir
rocks and is predominantly poor for non-reservoir rocks. MTER for unimodal pore
throat distribution ranges between 0.0034 – 0.7704 microns for reservoir rocks
and 0.0034 – 0.0224 microns for non-reservoir rocks. In this study we demonstrated
the links between petrophysical characteristics and facies distribution of
reservoir and non-reservoir rocks from the Anadarko Basin, Oklahoma.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California