1
Primary funding is provided by
The SPE Foundation through member donations
and a contribution from Offshore Europe
The Society is grateful to those companies that allow their
professionals to serve as lecturers
Additional support provided by AIME
Society of Petroleum Engineers
Distinguished Lecturer Programwww.spe.org/dl
James Hemingway
Petrophysics Advisor
Schlumberger
Society of Petroleum Engineers
Distinguished Lecturer Programwww.spe.org/dl
2
Formation Evaluation Using
Measurements made
Through Casing
Reservoir description using information
from cased hole logs rather than openhole
logs is a little like comparing Fred Astaire to Ginger Rogers.
“She did everything he did, except she did it backwards
and in high heels”
In nearly every situation the quality of data
acquired in openhole will be better than that
acquired behind casing. This is simply due
to the fact that a measurement made behind
steel pipe and a cement sheath of unknown
quality and thickness will be more effected
by it’s environment than a similar
measurement done without the presence
of casing or cement."Sure he was great, but don't forget that
Ginger Rogers did everything he did,
backwards…and in high heels."
Robert Thaves 1982
3
4
Easy Way or the Hard Way?
Openhole Vs Cased Hole Logging
Openhole
Better Data Quality
Fewer environmental effects
More measurement choices
Completion decision prior
to setting casing
Cased Hole
Not using valuable rig time
Much lower risk of tool loss
including radioactive sources
Ease of deployment
Use of tractors in high angle
and horizontal wellbores
Evolution of Cased Hole Formation Evaluation
FE began with (of course) only open hole logs in 1927.
Cased hole designs: S (1960’s) and Carbon/Oxygen (70’s)
Migration of OH measurements to CH environment
– Neutron porosity
– Sigma
– Sonics
– Spectroscopy & carbon/oxygen
– Resistivity
– Wireline formation testing
- - density ?
5
Approximately 95% of horizontal wells are not logged.
Completions are often designed before the well is drilled.
Comments from a SIG meeting on unconventional
reservoirs:
1 “ Once the well is drilled what would you do
with the information”
2 “Before the well is drilled the completion has already
been designed by the engineers”
3 “When drilling a Hz well you should know where you are.”
Geology is usually very flat.
When production results are available they show 30% to
40% of perforation stages are not producing6
0% 10% 20% 30% 40% 50%
1
5
9
13
17
21
25
29
33
% from Perf Cluster
Perf
Clu
ste
r
Well No 1
0% 5% 10% 15% 20%
1
4
7
10
13
16
19
22
25
% from Perf Cluster
Perf
Clu
ste
r
Well No 2
0% 5% 10% 15% 20% 25% 30%
1
4
7
10
13
16
19
22
25
28
% from Perf Cluster
Perf
Clu
ste
r
Well No 3
0% 2% 4% 6% 8% 10% 12% 14%
1
4
7
10
13
16
19
22
25
28
% from Perf Cluster
Perf
Clu
ste
r
Well No 4
Figure A
Snapshot of Production Log Results (4 of 109 wells) SPE 144326
Miller et al
7
– Neutron porosity
– Sigma
– Sonics
– Spectroscopy & carbon/oxygen
– Resistivity
– Wireline formation testing
- - density ?
8
Measurement and Fluid SensitivitySigma
0 100
CO2 OIL Salty Water
Hydrogen Index
0 1
CO2 Oil, Water
WaterCarbon Yield
CO2 OIL
Carbon to Oxygen RatioWater
CO2OIL
Gas
Gas
Gas
Gas
Burst On Inelastic RatioWaterCO2 OILGas
Fresh Water
– Neutron porosity
– Sigma
– Sonics
– Spectroscopy & carbon/oxygen
– Resistivity
– Wireline formation testing
- - density ?
11
Acoustic Measurements using
Coherence ProcessingSlotted
Time
Wavefo
rm n
um
ber
Time
Wavefo
rm n
um
ber
Solid Mandrel
Time
Wavefo
rm n
um
ber
Time
Wavefo
rm n
um
ber
Open
hole
Cased
hole
12
– Neutron porosity
– Sigma
– Sonics
– Spectroscopy & carbon/oxygen
– Resistivity
– Wireline formation testing
- - density ?
13
Gamma Spectroscopy measurements from
Martian surface prove existence of water
on the surface of Mars
Press release February, 2002
Courtesy of NASA/JPL/Caltech
15
Pulsed Neutron Spectroscopy measures the rock matrix
Quartz, feldspar
Calcite, dolomite
Clay
Muscovite
Elemental abundance
in earth’s crust
O 46.7
Si 27.6
Al 8.1
Fe 5.1
Ca 3.7
Na 2.8
K 2.6
Mg 2.1
S, Ti, Gd, Mn
> 99 %
Carbon16
TOC from Inelastic Spectroscopy
MeasurementTOC = Total Carbon – Inorganic Carbon
(TC) (TIC)
Integration of Inelastic and
Capture gamma ray spectra
allows to determine TOC
18
– Neutron porosity
– Sigma
– Sonics
– Spectroscopy & carbon/oxygen
– Resistivity
– Wireline formation testing
- - density ?
19
Water
entries, low
resistivity
Oil entries,
high
resistivity
CHFR / PLT Data
(SPE 71715 AGIP North Sea)
3 300
CHFR ILD
1 0
CHFRGR
0 3000
OIL
FLOW
0 5000
WATER
FLOW
20
– Neutron porosity
– Sigma
– Sonics
– Spectroscopy & carbon/oxygen
– Resistivity
– Wireline formation testing
- - density
22
Extend Spine & Ribs Methodology for CH
Open Hole
• Only one environmental
effect: mudcake
• rLS, rSS: response with
no mudcake
• One spine (density
response)
• Rib compensates for
mudcake
Cased Hole
• Two environmental effects:
cement and casing
• rLS, rSS : response with no
cement (but through-casing)
• A different spine (density
response) for every casing
thickness
• Rib compensates for cement
Start with
OH. Eqn. Modify for
casing
23SPWLA Paper KK 2010
An OH/CH
Triple-Combo
Log Suite
One dataset acquired in
Openhole.
The other data acquired
In cased hole
GR CH
GR OH
AHT90 OH
RT CH
HALC CH
TNPH OH
RHOZ CH
RHOZ OH
27
Lithology from Neutron
Induced Inelastic and
Capture Spectroscopy
Can be done in either
Open or cased wellbores
Openhole Cased Hole
Trip
le
Co
mb
o
EL
AN
Ima
ge
Fra
ctu
re
Cla
ss
De
nsi
ty
Str
ess
YM
E, P
R
A B C D E F G H
Full Evaluation Suite (Sonic Derived Stress vs.
Geochemical analysis Vs. Image)
30
Marcellus Example:Production increase of 80% over nearby wells using
an engineered design based on a better
reservoir description
31
Production improvement was directly attributed to the
identification and selection of low-stress intervals. Production
logging measurements confirmed the improved production rates.
Conclusions
• Formation evaluation in cased wells is
another option
• Many OH measurements can be made
in cased hole.
• Many applications require that data be
acquired in cased hole.32
Society of Petroleum Engineers
Distinguished Lecturer Programwww.spe.org/dl 33
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