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
