08-Analysis_behind_casing08-Analysis_behind_casing .ppt

08-Analysis_behind_casing

1. Analysis Behind Casing

2. 2CHFR
Oct 2002
Overview
•What is Analysis Behind Casing?
–an alternate way of data gathering
–measurements made behind casing where it makes sense,
complementing measurements made in other ways (OH-
WL/LWD, permanent sensors etc.)
•Measurements for ABC
•Summary

3. 3CHFR
Oct 2002
What is AnalysisBehindCasing?
•A formation evaluation from multiple sensors completed with
measurements made in cased hole
•Interpretation made using standard techniques and conventional
formation evaluation software
•Good candidates in cased hole are measurements that are insensitive
to the completion (e.g. CHFR), or characterized for known completion
conditions (e.g. RST)

4. 4CHFR
Oct 2002
Outline
•CHFR Applications
•Measurement Principle and Challenges
•Tool Specifications
•Job Planner
•Examples
•Conclusions

5. 5CHFR
Oct 2002
Cased Hole Formation Resistivity
•Resistivity-key for reservoir evaluation
since early days of well logging
•Need for resistivity behind casing
recognized in the past
•Recent advances have made this
measurement (CHFR) possible

6. 6CHFR
Oct 2002
Reservoir monitoring
Residual oil saturation
Location of bypassed
hydrocarbons
Primary evaluation
(no OH logs)
Applications

7. 7CHFR
Oct 2002
CHFR Toolstring
0.0m
Telemetry
Electronics
Insulating joint
Arm section
Hydraulics
Bottom
current
electrode
13.0m
Top
Current
electrode

8. 8CHFR
Oct 2002
CHFR Principle -Two Steps
Rt
Rc
DI
DI
Measure
Rt Formation Resistivity
Rc Casing Resistance
K Tool factor
Calibrate
Current Source
I
V1
V2
Vo
DRc
andDRc
Rt=K.Vo/DIwhere DI=(V1-V2)/Rc

9. 9CHFR
Oct 2002
CHFR Plus Specifications
•Tool dimensions 3-3/8”, 48’ long
•Pressure/Temperature 15000psi / 150°C (300°F)
•Casing O.D. Range 4.5” to 9-5/8”
•Stationary measurement ~ 1 -5 minutes
•Resistivity range ~ 1 ->100 Ohmm
•Depth of investigation ~similar to deep laterolog

10. 10CHFR
Oct 2002
Cement EffectCHFR, 7"OD casing, 0.75" cement thickness
-10
-5
0
5
10
15
20
25
30
0 1 10 100
Rt (Ohm.m)
Relative Error on Rt (%)
Rcem=0.1 Ohm.m
1 Ohm.m
2 Ohm.m
5 Ohm.m

11. 11CHFR
Oct 2002
Tool Planner
•Objective:
–Evaluate the feasibility of the job prior to it.
•Two questions will be answered
–Can I run the job with standard parameters
–If not with standard parameters, what parameter should I
modify to make the job feasible ?

12. 12CHFR
Oct 2002
Input Parameters
•Cable length
•Top log interval / Casing shoe depth
•Casing size & weight
•Number of cycles

13. 13CHFR
Oct 2002
CHFR Tool Planner -outputs

14. 14CHFR
Oct 2002
1600BWPD to 300BOPD after CHFR
300 bopd
1600 bwpd

15. 17CHFR
Oct 2002
BY-PASSED PAY IDENTIFICATION

16. 18CHFR
Oct 2002
Log Example -New Well OH/CH
Comparison
HLLD
CHFR
GR
Rc
Repeat
CHFR

17. 19CHFR
Oct 2002
100
200
300
New Well
CHFR run after
an LWD failure
(North Sea)
30’ zone
perforated, giving
12,000 bbls/day
dry oil.

18. 20CHFR
Oct 2002
Log
Example -
Washout
CHFR
reads
DEEP
Caliper = Bit Size + 8in.
CHFR remains stable

19. 21CHFR
Oct 2002
Log
Example -
Poor
Cement
0 -o-Csg resistance -o-100
(mW)
0 ___ Csg thickness __ 0.5
(USI) (in.)
Depth
(m) Cement Map
(USI)
1 -------------Open-hole Deep Laterolog ----------1000
1 -o---------o-CHFR (Pass 1 &Pass 2) -o------o-1000

20. 22CHFR
Oct 2002
Log Example
New Well
OH/CH
Comparison
7” -23 lb/ft
TD 2020m
Good Match between OH
and CHFR at ~600 ohm-m

21. 23CHFR
Oct 2002
Bypassed Oil
in unexpected
zones
Original OWC
After field is
swept OWC
moved
The “new” zone
produced 2050 BPD oil
with no water cut.

22. 24CHFR
Oct 2002
Alaska
Canada
Midland
Abu DhabiBakersfield
Qatar
North Sea
(UK,Norway)
Europe(Germany,France,Austria)
China
Indonesia
Tool Deployment
500+ Jobs to date
Nigeria

23. 25CHFR
Oct 2002
Conclusions
•Accurateresistivity through casing, with good repeatabilityin
various environments.
•Correction due to cement layer is minimal and similar to
traditional borehole corrections for resistivity tools.
•The CHFR measurement is deeperthan conventional
saturation monitoring from nuclear tools and allows direct
comparisonwith open hole resistivity logs.
•CHFR locates bypassed oiland increases reserveswith no
environmental and minimal financial risk for our clients.