This document discusses the use of cesium formate brine as a drilling, completion, and workover fluid for high pressure, high temperature (HPHT) gas wells over the past 10 years. Some key points: - Cesium formate brine is non-toxic, compatible with reservoirs, and less corrosive than other brines like bromide brines. - It has been used successfully in over 40 HPHT gas fields worldwide, enabling improved well control and safer drilling operations compared to other fluids. - Specific examples from the North Sea highlight its effectiveness as a combined drill-in and completion fluid, resulting in low skin factors and high well productivity.

1. SPE 145562
Life Without Barite: Ten Years of
Drilling Deep HPHT Gas Wells With
Cesium Formate Brine
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October

2. Cesium formate brine : Drill-in, completion,
workover and suspension fluid for HPHT gas wells
• Density up to 19.2 ppg/SG 2.3
• Drill-in and completion fluid
• Non-toxic, non-hazardous – safe to handle
• Little or no risk to the environment
• Compatible with all reservoirs
• Extends the thermal stability of polymers
• Less corrosive than bromide brines
• Stabilises shales
• Inhibits hydrates
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 2

3. Cesium formate brine produced by Cabot in
Canada from pollucite ore
Pollucite ore
Cs0.7Na0.2Rb0.04Al0.9Si2.1O6·(H20)
• Mined at Bernic Lake, Manitoba
• Processed on site to Cs formate brine
• Cs formate brine production 8,000 bbl p.a. of 19.2 ppg
• Brine stocks > 30,000 bbl @ 19.2 ppg
• Brine supplied on leasing terms (i.e. per bbl per day)
• Currently manage 30-40 jobs per year
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 3

4. Leasing cesium formate brine
Green and sustainable model – recognised by United Nations
Conservation ( i.e. minimisation of cesium formate brine losses during
transport, use and reclamation) is a key and essential feature of Cabot’s
Chemical Leasing business model
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 4

5. 42 deep HPHT gas fields developed using potassium
and cesium formate brines, 1995-2011
Country Fields Reservoir Description
Matrix Depth, TVD Permeability Temperature
type (metres) (mD) (oC)
Germany (7) Walsrode,Sohlingen Sandstone 4,450-6,500 0.1-150 150-165
Voelkersen,I dsingen,
Kalle, Weissenmoor,
Simonswolde
Hungary (2) Mako , Vetyem Sandstone 5,692 - 235
Kazakhstan (1) Kashagan Carbonate 4,595-5,088 - 100
Norway (10) Huldra ,Njord Sandstone 4,090-7,380 50-1,000 121-200
Kristin,Kvitebjoern
Tune, Valemon
Victoria, Morvin,
Vega, Asgard
Pakistan (2) Miano, Sawan Sandstone 3,400 10-5,000 175
Saudi Arabia (7) Andar,Shedgum Sandstone 3,963-4,572 0.1-40 132-154
Uthmaniyah
and
Hawiyah,Haradh
Tinat, Midrikah carbonate
UK (12) Braemar,Devenick Sandstone 4,500-7,353 0.01-1,000 123-207
Dunbar,Elgin
Franklin,Glenelg
Judy, Jura, Kessog
Rhum, Shearwater
West Franklin
USA (1) High Island Sandstone 4,833 - 177
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 5

6. Conventional formate drilling fluid formulation -
in field use since 1993 and good to 320oF
Simple, effective, non-damaging reservoir drill-in fluid
Component Function Concentration
Density
Lubricity
Formate brine 1 bbl
Polymer protection
Biocide
Viscosity
Xanthan 0.75 - 1 ppb
Fluid loss control
Ultralow vis PAC and modified
Fluid loss control 3 or 4 ppb of each
starch
Sized calcium carbonate Filter cake agent 20 ppb
Buffer
K2CO3/KHCO3 0 – 6 ppb
Acid gas corrosion control
Used to drill entire wells, top to bottom, in sensitive environments (e.g. Barents Sea)
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7. Formate-based drilling fluids
7

8. Cesium formate brine
Where does it provide the highest value ?
As a combined drill-in and completion fluid - enabling
operators to construct high-angle open hole screen
completions in HPHT tight gas reservoirs
• Combined drilling and completion fluid (“one filtrate”)
• Non-damaging to reservoir and screens
• Cleans-up naturally during start-up (10-20 hours)
• Low skins
• No well stimulation required
Perhaps the only fluid that can do this in an HPHT environment
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9. Advantages of open hole screen completions in
high-angle HPHT wells*
Improved economics and lower risk
• Maximise reservoir contact and production
- Larger inflow areas in contact with reserves
- Allow higher flow rates with lower flow resistance
- Good results (low skins) with stand-alone screens
• Lower cost
- Quicker and easier to install, less NPT
- 10% lower tangibles cost
• More robust than cased holes
- Less affected by formation compaction over time
• Lower HSE risk than cased holes
- No explosives , no live well work, fewer lifts, etc
* From “HPHT Wells Best Practices Course” by Think Well Ltd
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 9

10. Cesium formate brine used by BP and Statoil as
combined HPHT drill-in and completion fluid in N. Sea
28 high-angle development* wells drilled and completed in 6
HPHT offshore gas fields
• Huldra (6 )
• Devenick (1)
• Kvitebjoern (8 O/B and 5 MPD)
• Valemon (1)
• Kristin (2)
• Vega (5)
* Except Devenick and Valemon (appraisal wells)
Mostly open hole stand-alone sand screen completions
Also Tune field : drilled with 13.3 ppg K formate brine , completed in K/Cs formate brine and
suspended in K/Cs formate brine for 6-12 months
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 10

11. Tune field – semi-HP/HT gas reservoir in the North
Sea drilled and completed with formate brines
4 wells : 1,100-2,950 ft (350-900 m) horizontal reservoir sections. Suspended for 6-12
months in K/Cs formate brine after completion
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 11

12. HPHT gas fields in northern North Sea drilled
and completed with cesium formate brine
Almost every field development (oil and gas) on this map has used formate brines as well
construction fluids . Zinc bromide brine no longer used in Europe – too hazardous and damaging
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 12

13. HPHT gas fields in the Norwegian Sea drilled
and completed with cesium formate brine
Formate brines also used as well construction fluids in Asgard, Draugen, Morvin and Njord fields
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 13

14. Cesium formate brine first used as a combined
drill-in and completion fluid in the Huldra field,
2001
• Offshore Norway
• Gas condensate field
• 6 wells
• BHST: 297oF (147oC)
• TVD : 12,795 ft (3,900 m)
• Fluid density: 15.76- 16.34 ppg (SG1.89-1.96)
• 754-1,125 ft (230-343 m) x 81/2” reservoir sections
• Hole angle : 45-55o
• 1–2 Darcy sandstone
• Open hole completions, 6 5/8” wire wrapped screens
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 14

15. Huldra – drill-in, logging and completion times
(days) with cesium formate brine in well
A-4 A-5 A-6 A-8 A-9 A-11 Average
(189 m ) (263 m) (344 m) (257 m) (230 m) (336 m) (231 m)
Drill-in 5 8 20 15 7 11 11
Logging 0 3 1 7 3 2 2.7
Lower
11 6 5 6 5 5 6.3
completion
Upper
4 5 4 4 9 4 5
completion
Total 20 22 30 32 24 22 25
Drill, log and run lower completion in drilling fluid. Then displace to clean cesium
formate brine and run upper completion. Finally displace to packer fluid
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 15

16. Huldra – Fluid losses while drilling (cubic metres)
A-4 A-5 A-6 A-8 A-9 A-11 Average
(189 m ) (263 m) (344 m) (257 m) (230 m) (336 m) (231 m)
With cuttings 2.6 16.4 48 9.6 23.8 17.7 19.7
Other surface 1.5 3.3 10.1 2.2 12 17.1 7.7
Downhole 7.6 10.8 46.4 0 0 0 10.8
Well
5.6 28.3 12.8 24.3 11 15.7 16.3
displacements
Tripping 6.5 7.2 6.3 3.6 1.6 2.8 4.7
TOTAL 23.8 66 123.6 39.7 48.4 53.3 59.1
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 16

17. Huldra – Production of recoverable gas and
condensate reserves since 2001 (NPD data)
Plateau production from first 3 wells
120.00
Gas
Recovery of Reserves (% of original estimate)
Condensate
- 10 MM m3 gas /day 100.00
- 30,000 bbl/day condensate 80.00
60.00
80% of hydrocarbon reserves produced 40.00
by Year 6
20.00
0.00
0 2 4 6 8 10
Time since start-up (years)
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 17

18. Gas production from Tune and Huldra fields drilled
and completed with K/Cs formate brine
90% recovery of gas reserves (16-18 billion m3) produced in 7 to 8 years
100
90
Recovery of Gas Reserves (%)
80
70
60
50
Huldra
40
Tune
30
20
10
0
0 5 10 15
Time since start-up (years)
Source : Norwegian Petroleum Directorate- Fact Pages - November 2009
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 18

19. Condensate production from Tune and Huldra fields
drilled and completed with K/Cs formate brine
90% recovery of condensate reserves (3-5 million m3) produced in 5 to 7
120
years
Recovery of Condensate Reserves (%)
100
80
60
Huldra
Tune
40
20
0
0 5 10
Time since start-up (years)
Source : Norwegian Petroleum Directorate- Fact Pages - November 2009
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 19

20. Seven years of cesium formate brine use as
combined drill-in and completion fluid in Kvitebjoern
field, 2004 -present
• Offshore Norway, 190 m water depth
• Gas condensate field, 775 bar
• 13 wells to date – 8 O/B, 5 in MPD
• BHST: 311oF (155oC)
• TVD : 13,120 ft (4,000 m)
• Fluid density: 16.8 ppg (SG 2.02) for O/B
• 914 -1,910 ft (279-583 m) x 81/2” reservoir sections
• Hole angle : 20-40o
• 100 mD sandstone, long interbedded shale and coal sequences
• 6 wells completed in open hole : 300-micron single wire-wrapped
screens. Remainder cased
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 20

21. A few of the highlights from Kvitebjoern
Completion
Kvitebjoern time
well (days) Operator comments after well testing (Q3 2004 )
A-4 17.5 “The target well PI was 51,000 Sm3/day/bar This target
would have had a skin of 7”
A-5 17.8
“A skin of 0 would have given a PI of 100,000”
A-15 14.8
“THE WELL A-04 GAVE A PI OF 90,000 Sm3/day/bar
A-10 15.9 (ANOTHER FANTASTIC PI)”
A-6 12.7 *
The Well PI was almost double the target
Fastest HPHT well completion
in the North Sea
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 21

22. Economic benefits from the use of cesium
formate brine in HPHT gas field developments
Improved HPHT well control and safety
• No well control incidents in 28 HPHT drilling and completion ops
over 10 years (maybe 800 days in HPHT high-angle open hole ?)
• Factors contributing to improved well security and safety:
- Elimination of barite and its sagging problems
- Elimination of oil and its gas solubility problem
- Low solids brine  Low ECD* and swab pressures
- Inhibition of hydrates
- Ready/rapid surface detection of well influx
- No hazardous zinc bromide !
* ECD in Huldra, Kvitebjoern and Kristin wells : 0.33-0.50 ppg (SG 0.04-0.06)
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October
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23. Economic benefits from the use of cesium
formate brine in HPHT gas field developments
Improved well performance and recovery of reserves
• “High production rates with low skin” *
• “ We selected cesium formate to minimise well control problems
and maximise well productivity”*
* Quotes by Statoil relating to Kvitebjoern wells (SPE 105733)
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 23

24. Economic benefits from use of cesium
formate brine in HPHT gas field developments
Faster completions
- Drill-in and completing with cesium
formate allows open hole completion
with screens
- Clean well bores mean no tool/seal
failures or blocked screens
- Completion time 50% lower than wells
drilled with OBM
Time saved per well: 25 days
Quote by operator:“ fastest HPHT completion operation ever performed in North Sea (12.7 days)”
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 24

25. Economic benefits from use of cesium
formate brine in deep gas field developments
Operational efficiencies Lower NPT Lower costs
Flow check fingerprint
• No differential sticking for a Huldra well
• No well bore instability*
Duration of
flow back
Fluid Gain
(bbl)
(minutes)
• Pipe and casing running speeds are fast
30 0.8
• Mud conditioning and flow-check times are short
15 0.56
• Displacements simplified, sometimes eliminated
20 0.44
Formate drilling fluid = formate completion fluid
30 0.56
* Quote by operator : “ No washouts were experienced in any of the wells during drilling through long sections of
interbedded shales in the Kvitebjoern reservoir (50/50 shale and sand ) with cesium/potassium formate fluid”
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 25

26. Economic benefits from the use of cesium
formate brine in HPHT gas field developments
Good reservoir definition
• High density filtrate and no barite
• Filtrate Pe up to 259 barns/electron
• Unique Cs feature - makes filtrate invasion
highly visible against formation Pe of 2-3 b/e
• Ideal for defining permeable sands
• Consistent and reliable net reservoir definition
from LWD
“Using photoelectric factor and bulk density data, combined with resistivity measurements from both
the LWD drill pass and the ream pass, produces a very reliable and consistent net reservoir
definition.” (SPE 105733)
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 26

27. Economic benefits from the use of cesium
formate brine in HPHT gas field developments
Good reservoir definition
• Highly conductive fluid
• Clear resistivity images
• Information provided:
- structural dip
- depositional environment
- geological correlations
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 27

28. Summary
10 years of field use has demonstrated that cesium formate brine
can improve the economics of HPHT gas field developments by:
• Enabling long high-angle well constructions completed in
open hole with screens
• Making the well construction process faster and easier
• Improving well/operational safety and reducing risk
• Delivering unimpaired wells with high production rates
• Enhancing reservoir definition
2011 SPE/IADC Middle East Drilling Technology Conference, Muscat, 24-26 October 28

29. www.formatebrines.com
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