Characterisation of carbonate reservoir heterogeneity using borehole image logs

Carbonate heterolithic classification/1
Image log & dipmeter analysis course
Image log & dipmeter analysis course
Characterisation of carbonate reservoir
Characterisation of carbonate reservoir
heterogeneity using borehole image logs
heterogeneity using borehole image logs
Carbonate heterolithic classification/2
1 km
100 m
200 microns
Scales of carbonate reservoir heterogeneity
Scales of carbonate reservoir heterogeneity
Carbonate heterolithic classification/3
•
Borehole imaging tools
•
Heterogeneities
–
Structural – fractures/faults
–
Depositional and diagenetic
–
Pore system evaluation
•
Reservoir rock typing
•
Conclusions
Outline
Outline
Carbonate heterolithic classification/4

channels
channels
reefs
reefs
slide blocks
slide blocks
0.1 mm 100 m 1 km 10 km1 m 10 m1 cm 10 cm1 mm
CORE
CORE
(Limited Coverage)
BOREHOLE IMAGES
BOREHOLE IMAGES
3D SEISMIC
3D SEISMIC
(Limited Resolution)
fracture width
fracture width
ripples
ripples
dish structures/dewatering
dish structures/dewatering
bioclasts
bioclasts
soft sediment deformation
soft sediment deformation
scours/erosion surfaces
scours/erosion surfaces
grain size/bed thickness trends
grain size/bed thickness trends
bedforms

bedforms
channel lags
channel lags
slumps
slumps
Scales of investigation
Scales of investigation
Carbonate heterolithic classification/5
•
Fractures
–
Closed or open
–
Natural or drilling induced
–
Orientation, spacing and frequency
•
Faults
–
Determine strike and dip of the fault
–
Determine rock displacement along the
fault
–
Reservoir compartmentalisation
•
In-situ stresses
–
Borehole breakout
–

Drilling induced fractures
–
Potential & artificial fracturing
•
Input to fracture modeling
Static
Dynamic
3 6 7 2
N
Structural heterogeneities
Structural heterogeneities
Carbonate heterolithic classification/6
Micro-resistivity
Acoustic
Fracture
Bedding
Feature classification and characterisation
Feature classification and characterisation
Carbonate heterolithic classification/7
15 ft
Non-stylolitic, conductive, bed boundary
(a)
9 ft
Conductive fault with resistive halo
(f)
Conductive fracture cutting resistive fracture
5 ft
(e)
Stylolitic, conductive, resistive & mixed fractures
15 ft

(d)
9 ft
Resistive fracture
(c)
15 ft
Stylolitic, conductive bed boundary
(b)
15 ft
Non-stylolitic, conductive, bed boundary
(a)
9 ft
Conductive fault with resistive halo
(f)
Conductive fracture cutting resistive fracture
5 ft
(e)
Stylolitic, conductive, resistive & mixed fractures
15 ft
(d)
9 ft
Resistive fracture
(c)
15 ft
Stylolitic, conductive bed boundary
(b)
15 ft
Non-stylolitic, conductive, bed boundary
(a)
15 ft
Non-stylolitic, conductive, bed boundary

15 ft
Non-stylolitic, conductive, bed boundary
15 ft15 ft
Non-stylolitic, conductive, bed boundary
(a)
9 ft
Conductive fault with resistive halo
(f)
9 ft
Conductive fault with resistive halo
9 ft
Conductive fault with resistive halo
9 ft9 ft
Conductive fault with resistive haloConductive fault with resistive halo
(f)
Conductive fracture cutting resistive fracture
5 ft
(e)
Conductive fracture cutting resistive fracture
5 ft
Conductive fracture cutting resistive fracture
5 ft
Conductive fracture cutting resistive fracture
5 ft5 ft
(e)
Stylolitic, conductive, resistive & mixed fractures
15 ft
(d)
Stylolitic, conductive, resistive & mixed fractures
15 ft

Stylolitic, conductive, resistive & mixed fractures
15 ft
Stylolitic, conductive, resistive & mixed fractures
15 ft15 ft
(d)
9 ft
Resistive fracture
(c)
9 ft
Resistive fracture
9 ft
Resistive fracture
9 ft9 ft
Resistive fracture
(c)
15 ft
Stylolitic, conductive bed boundary
(b)
15 ft
Stylolitic, conductive bed boundary
15 ft15 ft
Stylolitic, conductive bed boundary
(b)
Micro-resistivity images in horizontal well displayed as pseudo-core sticks
Feature classification
Feature classification
Carbonate heterolithic classification/8
CBIL
sm
ACOUSTIC

EARTH Imager
sm
GR HEXDIP
sm
5m
Fracture identification in oil based mud systems
Fracture identification in oil based mud systems
Carbonate heterolithic classification/9
•
For resistivity images:
–
Conductive (dark image) =/= Open?
–
Resistive (light) =/= Closed?
•
For Acoustic Images
–
low amplitude (dark) =/= Open?
–
high amplitude (light) =/= Closed?
•
Core calibration can be used to confirm
–
Image logs can only provide an interpretive
insight only
•
Only dynamic data provide true insight into
fracture “producibility”
Open versus closed fractures
Open versus closed fractures

Carbonate heterolithic classification/10
Flowmeter data
Conductive
(open) fractures
Acoustic
Calibration of image log data with core
Calibration of image log data with core
Carbonate heterolithic classification/11
Fault identification
Fault identification
Carbonate heterolithic classification/12
BIU 1
BIU 3A
BIU 2
BIU 3B
Formation
Test
Data
(psi)
110.3
26.2
26.2
25.5
10.4
11.8
9.5
12.8
8.9
8.6
7.9

BIU 3B
BIU 2
BIU 1
Bedding contact
WSW
ENE
MINOR
FAULT B
MINOR
FAULT A
MAJOR
FAULT A
BIU 3A
Fault compartmentalisation
Fault compartmentalisation
Carbonate heterolithic classification/13
•
Well and fracture orientation
•
Fracture density
•
Core density calibration
•
Borehole corrected
fracture density
•
Fracture spacing
•
Fracture length?
•

3D modelling
Schematic path
down borehole
(69* / 210*)
Schematic path
down borehole
(69* / 210*)
Mesozoic carbonate
Oil staining
OBLIQUE-SLIP
Fracture distribution
Fracture distribution
Carbonate heterolithic classification/14
•
Increased compartmentalisation
–
Permeability barriers
•
Increased communication
–
Permeability conduits
•
Overall objective - producibility
–
Fracture model inputs
–
Fault seal predictions
–
Production enhancement
–

Completion strategy
–
Selection of perforation intervals
GO
GO
Fracture characterisation
Fracture characterisation
Carbonate heterolithic classification/15
•
Image facies assigned on basis of image
character, open hole log response
•
Image response is related to electrical or
acoustic properties, responds to rock
texture, fluid saturation and mineralogy
•
Not possible to distinguish all core
lithofacies
•
Calibration with core allows a meaningful
geological interpretation of image logs
Image facies
Image facies
Carbonate heterolithic classification/16
Stylolitic seams
Conductive,
tension gashes
Resistive
cemented
limestone

Dissolution
seam
Stylolites and dissolution seams
Stylolites and dissolution seams
Carbonate heterolithic classification/17
Cross-bedding
Cross-bedding
Carbonate heterolithic classification/18
STATIC DYNAMC
STATIC DYNAMCSTATIC DYNAMC
STATIC
DYNAMC
STATIC DYNAMC
STATIC
DYNAMC
Nodular limestone image facies
Nodular limestone image facies
Carbonate heterolithic classification/19
0
10
20
30
40
50
60
% B-Zone
Image facies
0
10
20

30
40
50
60
% B-Zone
Image facies
0
10
20
30
40
50
60
% B-Zone
Image facies
0
2
4
6
8
Average thickness (ft)
Image facies
0
2
4
6
8
Average thickness (ft)
Image facies
0

2
4
6
8
Average thickness (ft)
Image facies
0
2
4
6
8
Average thickness (ft)
Image facies
Well 4 - uncored
Well 3
Well 2
0
10
20
30
40
50
60
% B-Zone
Image facies
Well 1
IF1 IF2 IF3 IF4 IF5 IF6 IF7 IF8 IF9 IF10 IF11
Image facies
Image facies
statistics

statistics
Carbonate heterolithic classification/20
•
Identification, orientation and
analysis of primary stratification
surfaces/heterogeneities
•
Identification of key stratal
surfaces
•
Borehole image facies analysis
•
Depositional modelling
•
Sequential analysis
•
Pore fabric analysis
•
porosity and permeability
distribution
•
Palaeotransport/reservoir
geometry analysis
Depositional heterogeneities
Depositional heterogeneities
Carbonate heterolithic classification/21
Thin bed identification
below the resolution of
openhole logs
STAT

DYN
MINIPERM
PROFILE
High resolution image log response
High resolution image log response
Carbonate heterolithic classification/22
Resistivity Image Resistivity ImageAcoustic Image Acoustic ImageResistivity Image Resistivity ImageAcoustic Image Acoustic Image
Reef core
Back-reef lagoon
Image log facies analysis – reef facies
Image log facies analysis – reef facies
Carbonate heterolithic classification/23
Oil based mud
Facies stacking patterns and dip analysis
Facies stacking patterns and dip analysis
Carbonate heterolithic classification/24
Image facies show
an overall
coarsening/ shoaling-
upward trend with
increasing stacking
pattern in upper part
of reservoir
Stacked
fining-upward
grain/pack/
wackestone
units
Mostly trendless
succession of

mudstone/
wackestones
Interpretation
Coarse, vuggy rudist
float to rudstones
Image facies prediction in uncored wells
Image facies prediction in uncored wells
Carbonate heterolithic classification/25
Reservoir architecture
Reservoir architecture