Figure 5105 pore size comparison for carbonates with

Figure 5.105. Pore size comparison for carbonates with touching vugs.
Pore and Pore throat distributions
Diagenesis enhanced - intercrystalline pores - carbonate
0
1
2
3
4
5
0.01 0.1 1 10 100 1000 10000
Pore Diameter (microns)
Population Density
0
5
10
15
20 NMR pore
size: rho=5,
spheres
NMR pore
size: rho=15,
spheres
Pc throat
size
Pore volume (%)
PIA ave
<20μm
PIA ave
20-500 μm
Pc
MPA
T2 mode @
max phi
(spheres,
ρ =15μ/sec)
K=35md
Pore and Pore throat distributions
Diagenesis enhanced - touching vugs - carbonate
0
1
2
3
4
5
0.01 0.1 1 10 100 1000 10000
Pore Diameter (microns)
Population Density
0
5
10
15
20
NMR pore
size: rho=5,
spheres
NMR pore
size:
rho=1200,
spheres
NMR pore
size: rho=40,
spheres
Pc throat size
Pore volume (%)
PIA ave
<20μm
PIA ave
20-500 μm
Pc
MPA
T2 mode @
max phi
(spheres,
ρ =200μ/sec)
K=51md

171
Figure 5.106. Pore size comparison for carbonates with non-touching vugs.
Figure 5.107. Pore size comparison for carbonates with cement-reduced pores.
Pore and Pore throat distributions
Diagenetic pores - Carbonates
Porosity enhancing - non - touching vugs
0
1
2
3
4
5
0.01 0.1 1 10 100 1000 10000
Pore Diameter (microns)
Population Density
0
5
10
15
20
NMR pore
size: rho=5,
spheres
NMR pore
size: rho=15,
spheres
Pc throat
size
Pore volume (%)
PIA ave
<20μm
PIA ave
20-500 μm
Pc
MPA
T2 mode @
max phi
(spheres,
ρ =15μ/sec)
K=383md
Pore and Pore throat distributions
Diagenesis reduced - cementation - carbonate
0
0.1
0.2
0.3
0.4
0.5
0.001 0.01 0.1 1 10 100 1000 10000
Pore Diameter (microns)
Population Density
0
5
10
15
20
NMR pore
size: rho=5,
spheres
Pc throat
size
Pore volume (%)
PIA ave
Not measurable
Pc
MPA
T2 mode @
max phi
(spheres,
ρ =5μ/sec)
K=0.002md

172
CHAPTER VI
DISCUSSION AND INTERPRETATION
Shape templates were measured as test objects with PIA (Chapter IV) and
compared to pore geometry in thin sections. PIA distinguished between depositional,
diagenetic, and hybrid pores on the basis of pore sizes and shapes. Pore geometry was
found to correlate strongly with pore origin. PIA measurements were useful in
estimating measured core analysis values of porosity particularly on rocks with
depositional pores. Diagenetic (vuggy) and hybrid 1-b (moldic) pores underestimated
measured core analysis porosity by approximately 7 and 15%, respectively. Other
diagenetic pore types such as intercrystalline and cemented pores were difficult to
measure with PIA because of their small sizes and such measurements showed little or
no direct relationship between 2-D and 3-D porosity. The value of PIA to estimate 3-D
from 2-D porosity in carbonate core plugs decreased in relation to the degree and type of
diagenetic alteration. Pore origin was a useful indicator in grouping and comparing the
relative precision of 2-D and 3-D porosity measurements, however.
NMR T2 curves were converted into pore size distributions, and compared to
distributions of pore size as measured in 2-D using PIA. Distributions of small
(<0.02mm), medium (0.02-0.5mm), and large (>0.5mm) pores showed that medium
pores were the most useful in discriminating pore geometry in depositional, hybrid, and
intercrystalline pores; the larger pore sizes were most useful in samples with vugs.