The document discusses comparisons between different pulsed neutron logging tools, including: 1) An RST and TDT comparison showing contacts in a well producing from two zones, with the TDT picking the contact at 8,052 feet. 2) A TMD and TDT comparison in a well producing oil but the TDT was reading a water saturation of 50%, until a TMD run found the actual water was coming from the base of the tubing at 13,425 feet. 3) A comparison of memory and wireline PNC logs in a frac and pack completion where the memory PNC read a higher sigma of 23 counts in the gas zone versus 10 counts for the wireline PNC.

1. BP Exploration and Production Technology
Surveillance Program
Pulsed Neutron Logs
PNL Capture and Inelastic Measurements
By Ray Wydrinski
SPWLA Nuclear Logging Special Interest Group
October 25, 2006

2. GR
GAPI
0 150
SIBHTDTP
CU
400 0
FBAC
CPS
0 5000
FBACTDTP
CPS
0 100
DEPTH
FT
SIGMTDTP
CU
60 0
SIGM
CU
60 0
TPHI
CFCF
0.6 0
TPHITDTP
CFCF
0.6 0
-- O/W Contact --
8000
8100
RST and TDT Comparison
Frac and Pack Completion
• Well has 2 zones producing.
Objective was to see the
contacts.
• Year was 2000 where RST
was replacing TDT-P. The
logs were run on the same
day.
• Logs were run with the well
flowing.
• TDT picked the contact are
8,052’ which fit in with the
reservoir models.
History
• Hole size = 9.87”
• Casing Size = 7.625”
• Tubing = 2.375”, Centered
• No gravel in the tubing /
casing annulus.
Completion

3. GR
GAPI
0 150
SIBHTDTP
CU
400 0
FBAC
CPS
0 5000
FBACTDTP
CPS
0 10000
DEPTH
FT
SIGMTDTP
CU
60 0
SIGM
CU
60 0
TPHI
CFCF
0.6 0
TPHITDTP
CFCF
0.6 0
Blast Joint
Oil interval
7700
7800
RST and TDT Comparison
Frac and Pack Completion
• Well has 2 zones
producing. Objective
was to see the
contacts.
• Year was 2000 where
RST was replacing
TDT-P. Both logs run
on the same day.
• Logs were run with the
well flowing..
• TDT picked the
contact at 7,738’. No
contact from the RST.
History
• Hole size = 9.87”
• Casing Size = 7.625”
• Tubing = 2.375”, Off-
Center
• No gravel in the tubing /
casing annulus
Completion

4. TMD vs. TDT Comparison
Frac and Pack Completion
VCLQ
DEC
0 1
GRAM
API
0 100
DSGRH
API
-20 80
TVD
FT
5000 15000
DEPTH
FT
PERF
unit
10 0
PACKER
unit
10 0
SLEAVE
unit
10 0
RACHM
ohm.m
0.2 20
RACLM
ohm.m
0.2 20
FDEN
G/CC
0 2
TEMP
DEGF
190 240
PHIEQ
DEC
1 0
BVWQ
DEC
1 0
SWQ
DEC
1 -1
SWCHS
dec
1 -1
TPHI
V/V
0.65 0.05
NPKSM
DECIMAL
0.6 0
SIGM
CU
60 0
DSSIGHD
60 0
13200
13300
13400
• Well is producing oil from upper perfs,
sleeve at 13,272’ is open, no water
!3,215’ to 13,278’.
• Lower perfs sleeve is closed. Zone
watered out a while back. (13,340’ to
13,405’).
• TDT was run to evaluate an upper non-
perforated zone for a potential new well.
• Why was the TDT water saturation
calculating 50% with the well flowing oil?
• After a few days – found no reason the
TDT Sigma should read too high – a
decision was made to run a TMD.
• Two days before the TMD run – the well
began to produce a little water (5 bwpd)
• Decided to run Oxygen Activation,
Gradiomanometer and Temperature
with the TMD.
• OA and temperature showed water
coming from 13,425’ which was at the
base of the tubing. At this time the well
was close to 60 bwpd.
• TMD sigma was very similar to the TDT
Sigma.
• Decision was made to plug the bottom of
the tubing. Water did not cut back.
• Well soon stop flowing due to the
amount of water.
• Conclusion: Don’t run a PNL in a well
that is producing water free (Ha Ha).
History

5. Memory PNC and Wireline PNC Comparison
Frac and Pack Completion
Memory PNL
• Scientific Drilling
(MPNN)
• Objective is to find the
water contact.
• Well is flowing
• Water salinity = 72,000
NaCL
• Sigma reads 23 cu in
gas zone.
Completion
• 2.875” perfed tubing,
centered
• 7.625” casing
• 8.5” bit size
• No gravel
• Frac and pack

6. Memory PNC and Wireline PNC Comparison
Frac and Pack Completion
• TDT-P
• Objective is to find the
water contact.
• Well is flowing
• Water salinity = 72,000
NaCL
• Sigma reads 10 cu in gas
zone.
Wireline PNL
• 2.875” perfed tubing,
centered
• 7.625” casing
• 8.5” bit size
• No gravel
• Frac and pack
Completion

7. Memory Scientific Drilling PNL (Multiple passes)
Memory PNC and Wireline PNC Comparison
Frac and Pack Completion

8. What needs to investigated?
• What has been done
– The gravel in the packs have no large neutron absorbers so there should be
little effect on the PNL.
– These gravel pack completions have been around for many years and we
have not seen the problem with older PDK-100, TDT-P and TMD logs.
– Frac and pack with gravel pack completions is something new.
• What needs to be done?
– Diffusion Corrections
– Better modeling
– Depth of investigation has decreased
– Other corrections