This document discusses carbonate sedimentology and how it differs from clastic sedimentology. Specifically, it notes that while interpretation techniques from clastic reservoirs can be applied to carbonates, carbonates are influenced more by biogenic processes and are susceptible to more diagenetic alterations. It also discusses various carbonate classification schemes, common sedimentary structures in carbonates like cross-bedding and biogenic structures, using well logs and core data to correlate carbonate lithofacies, how permeability varies between different lithofacies associations, and fractures in carbonate reservoirs.

1. Carbonate sedimentology/1
• Interpretation techniques applied to clastic
reservoirs can also be applied to carbonate
depositional systems.
• Carbonates however, differ from clastics due to
the importance of biogenic processes and their
susceptibility to diagenetic modifications.
Carbonates versus clastics

2. Carbonate sedimentology/3
Dunham (1962)
Carbonate classification

3. Carbonate sedimentology/4
Folk (1962)
Carbonate classification

4. Carbonate sedimentology/5
Sedimentary structures

5. Carbonate sedimentology/6
• All primary sedimentary structures recognised in
siliciclastic rocks can occur in carbonates
(e.g. cross-bedding in ooid shoals, slumps etc.)
• In addition there may be:
– Biogenic structures (reefs etc.)
– Diagenetic structures unique to carbonates
Sedimentary structures

6. Carbonate sedimentology/7
Carbonate lithofacies – core calibration
Vertical well
Boundary between FMI facies FMI7 and FMI4. The
burrowed surface is clearly visible (arrowed) as are the
packstone-filled burrows below.
Burrowed contact (dashed line)
between FMIF7 and FMIF4. Burrows
(squares) are filled with packstone.
Possible hardground.
FMIF7
FMIF4
Static image Dynamic image Slabbed core

7. Carbonate sedimentology/8
Carbonate lithofacies
FMI image facies associations vs Ka
0.01
0.10
1.00
10.00
100.00
1000.00
0 1 2 3 4 5 6
FMI image facies association
Ka
(mD)
FMIA1
FMIA2
FMIA3
FMIA4
FMIA5

8. Carbonate sedimentology/9
Conductive fracture
Resistive fracture
Fractures in carbonates
Vertical well

9. Carbonate sedimentology/10
The ultimate goal