Dolomite Perspectives on a Perplexing Mineral

T
2
cutoff
φ for
distribution
> long
T
2
cutoff
Meso-
porosity
Macro-
porosity
~ 5 
µm
~ 0.5 
µm
Macro-
porous
Micro-
macro
Macro-
micro
Macro-
meso
Micro-
porous
Micro-
meso
Meso-
micro
Meso-
porous
45. The PEF log is recorded as part of the density 
measurement. The PEF measurement is unitless, but 
because it is proportional to the photoelectric cross 
section per electron, it is sometimes expressed in
barns/electron.
46. Kho D, Al-Awadi M and Acharya M: “Application of 
Magnesium Yield Measurement from Elemental Capture 
Spectroscopy Tool in Formation Evaluation of Northern 
Kuwait Fields,” presented at the SPWLA 50th Annual 
Logging Symposium, The Woodlands, Texas,
June 21–24, 2009. 
26678schD5R1.indd 11
11/5/09 3:53 PM

---

Autumn 2009
43
>
Appraisal of a complex carbonate reservoir. In Track 1, a strong 
correlation is seen between the relative dry weight Mg measurement 
obtained by the ECS tool (green curve) and grain density measurements 
obtained through core analysis (red dots). The array induction resistivity 
data (Track 2) and conventional density (pink curve), neutron (blue curve) 
and sonic (green curve) data in Track 3 are used for computing porosity and 
water saturation. Track 4 shows the resulting lithology, porosity and fluid 
volumes computed by the Carbonate Advisor service. A good match 
between core data (red) and computed grain density (blue curve) and 
computed porosity (black curve) are seen in Track 5. The 
T
2
distribution 
measurement from the CMR combinable magnetic resonance tool (Track 6) 
is used for porosity partitioning, pore system classification and permeability 
computations. When the porosity partitioning result (Track 7) is compared 
with the computed lithology (Track 4), dolomite content shows a close 
correlation with the mesoporosity (green shading) and macroporosity (red 
shading). This formation shows a general correspondence between 
increases in dolomite content and pore size. Porosity is further related to 
permeability (Track 8). High permeability values generally correspond to 
zones of macroporosity (red shading). The computed permeability can be 
compared to core and MDT modular formation dynamics tester data (Track 9). 
Carbonate Advisor estimated permeability (black curve) matches the core 
permeability (red dots) and is confirmed by the MDT mobility reading
(blue dots).
MattV_ORAUT09_Fig_14 
ohm.m
0.2
2000
20-in. Resistivity
ohm.m
0.2
2000
30-in. Resistivity
ohm.m
0.2
2000
60-in. Resistivity
ohm.m
0.2
2000
90-in. Resistivity
ohm.m
0.2
2000
10-in. Resistivity
µs/ft
109
29
DT Compressional
%
0.45
- 0.15
Neutron Porosity
%
0.5
0
Core Porosity
mD
0.1
10,000
Core Permeability
mD/cP
0.1
10,000
MDT Mobility
mD
mD
0.1
10,000
0.1
10,000
Carbonate Advisor
Estimated Permeability
%
0.5
0
Computed Porosity
g/cm
3
2.5
3.5
Core Grain Density
g/cm
3
2.5
3.5
Computed Grain Density
0.015
–0.015
0.5
ft
3
/ft
3
0
0.5
ft
3
/ft
3
0
T
2
Distribution
Microporosity
Carbonate Advisor
Total Porosity 
Carbonate Advisor
Permeability
%
100
0
ELAN VOLUMES
g/cm
3
1.95
2.95
Density
Dolomite Grain Density
lbf/lbf
Rel. Dry Weight Mg
Core Grain Density
Depth,
ft
X,050
X,100
X,150
X,200
X,250
2.7
3
g/cm
3
g/cm
3
g/cm
3
2.7
3
0
0.25
Limestone Grain Density
2.7
3
Moved Water
Moved Hydrocarbon
Dolomite
Calcite
Kaolinite
Chlorite
Illite
Pyrite
Macroporosity
Mesoporosity
Macroporosity
Mesoporosity
Micro-macro
Micro-meso
Meso-micro
Microporosity
Macro-micro
Macro-meso
Anhydrite
Oil
Water
26678schD5R1.indd 43
12/9/09 7:30 AM

---

44
Oilfield Review
Core analysis confirmed the relationship 
between dolomite content and reservoir qual-
ity in this northern Kuwait field. The 3D 
crossplot shows a general trend of increasing 
dolomite content with increases in porosity 
and permeability 
(below left)
.