1. SPE 165151 Gunnar Olsvik and Siv Howard, Cabot Specialty Fluids John Downs, Formate Brine Ltd
The Long-Term Production Performance of Deep HPHT Gas Condensate Fields Developed Using Formate Brines
SPE European Formation Damage conference , Noordwijk, The Netherlands, 5-7 June 2013

2. SPE European Formation Damage conference, 5-7 June 2013
Formate brines
Sodium formate
Potassium formate
Cesium formate
Solubility
47 %wt
77 %wt
83 %wt
Density
1.33 g/cm lb/gal
1.59 g/cm lb/gal
2.30 g/cm lb/gal
Formates are also soluble in some non-aqueous solvents
SPE European Formation Damage conference, 5-7 June 2013

3. Formate brines for HPHT gas wells
Low-solids heavy fluids for deep HPHT gas well constructions
Reservoir drill-in
Completion
Workover
Packer fluids
Well suspension
Fracking (OHMS)
Used in hundreds of HPHT wells since 1995, including some of
Europe’s deepest, hottest and highly-pressured gas reservoirs
SPE European Formation Damage conference, 5-7 June 2013

4. Reservoir Description
42 deep HPHT gas fields developed using formate brines, * (published data)
Country
Fields
Reservoir Description
Matrix
type
Depth, TVD
(metres)
Permeability
(mD)
Temperature (oC)
Germany
Walsrode,Sohlingen
Voelkersen, Idsingen,
Kalle, Weissenmoor,
Simonswolde
Sandstone
4,450-6,500
Hungary
Mako , Vetyem
5,692 -
235
Kazakhstan
Kashagan
Carbonate
4,595-5,088
100
Norway
Huldra ,Njord
Kristin,Kvitebjoern
Tune, Valemon
Victoria, Morvin,
Vega, Asgard
4,090-7,380
50-1,000
Pakistan
Miano, Sawan
3,400
10-5,000
175
Saudi Arabia
Andar,Shedgum
Uthmaniyah
Hawiyah,Haradh
Tinat, Midrikah
and
carbonate
3,963-4,572
0.1-40 UK
Braemar,Devenick
Dunbar,Elgin
Franklin,Glenelg
Judy, Jura, Kessog
Rhum, Shearwater
West Franklin
4,500-7,353
0.01-1,000
USA
High Island
4,833
177
* Now more HPHT fields in Kuwait, India and Malaysia during
SPE European Formation Damage conference, 5-7 June 2013

5. The economic benefits of using formate brines in HPHT gas field developments – Reference papers
SPE (2010): “A Review of the Impact of the Use of Formate Brines on the Economics of Deep Gas Field Development Projects”
SPE (2011): “Life Without Barite: Ten Years of Drilling Deep HPHT
Gas Wells With Cesium Formate Brine”
SPE European Formation Damage conference, 5-7 June 2013 5

6. Formate brines – The economic benefits provided in HPHT gas field developments
Formate brines tend to improve oil and gas field development economics by :
Reducing well delivery time and costs
- 12 years of use with screens
- Very good with ESS
Improving well/operational safety
and reducing risk
Delivering production rates that exceed expectations
Providing more precise reservoir definition
SPE European Formation Damage conference, 5-7 June 2013

7. Several highlights from some Kvitebjoern HPHT gas wells drilled and completed with formates
Fast open hole screen completions and high well productivity
Kvitebjoern well
Completion time
(days)
A-4
17.5
A-5
17.8
A-15
14.8
A-10
15.9
A-6
12.7 *
Operator quote after well testing (Q )
“The target well PI was 51,000 Sm3/day/bar This target would have had a skin of 7”
“A skin of 0 would have given a PI of 100,000”
“THE WELL A-04 GAVE A PI OF 90,000 Sm3/day/bar
(ANOTHER FANTASTIC PI)”
The Well PI was almost double the target
* Fastest HPHT well completion
in the North Sea
SPE European Formation Damage Conference, 5-7 June 2013

8. But productive for how long ?
Objectives of the analysis presented in this paper :
Map the production profiles of North Sea HPHT fields
where formate brines were the last fluids to contact the
reservoirs in every well
Compare actual cumulative production over time against
published estimates of recoverable reserves at start-up
See if the well construction design influences the
production profile (e.g. Cased vs. Open hole completions)
SPE European Formation Damage conference, 5-7 June 2013

9. Reviewed long-term production from 8 North Sea HPHT gas condensate fields in 3 categories
Category
Fields
Reservoir penetration and well completion 1
Tune
Huldra
All production wells drilled and completed in high-angle open hole with formate brines. Single filtrate in reservoir. 2
Kvitebjørn
All production wells drilled and completed in high-angle open- and cased-holes with formate brines. Multiple filtrate types in reservoir surrounding cased holes. 3
Braemar
Glenelg
Jura
Rhum
West Franklin
All production wells drilled with oil-based mud, then completed in cased hole with formate brines as the perforating fluids (with and without kill pills).
Multiple filtrate types in all wells
Production data obtained from UK DECC and Norwegian NPD websites
SPE European Formation Damage conference, 5-7 June 2013

10. Tune field – semi-HP/HT gas condensate reservoir drilled and completed with formate brines, 2002
4 wells : m horizontal reservoir sections. Open hole screen completions. Suspended for 6-12 months in formate brine after completion
SPE European Formation Damage conference, 5-7 June 2013

11. Tune wells - Initial Clean-up – Operator’s view (direct copy of slide) June 2003
Wells left for 6-12 months before clean-up
Clean-up : hours per well
Well performance
Qgas 1.2 – 3.6 MSm3/d
PI 35 – 200 kSm3/d/bar
Well length sensitive
No indication of formation damage
Match to ideal well flow simulations (Prosper) - no skin
Indications of successful clean-up
Shut-in pressures  
Water samples during clean-up
Formate and CaCO3 particles
Registered high-density liquid in separator
Tracer results
A-12 T2H non detectable
A-13 H tracer indicating flow from lower reservoir first detected 5 sd after initial clean-up <-> doubled well productivity compared to initial flow data
No processing problems Oseberg Field Center 11
SPE European Formation Damage conference, 5-7 June 2013

12. Tune – Production of recoverable gas and condensate reserves since 2003 (NPD data)
Good early production from the 4 wells
- « No skin»
million m3 gas /day
- 23,000 bbl/day condensate
Good sustained production
- 90% of recoverable hydrocarbon
reserves produced by end of Year 7
NPD current estimate of RR:
billion m3 gas
- 3.3 million bbl condensate
Open hole screen completions and single filtrate
SPE European Formation Damage conference, 5-7 June 2013

13. Huldra field – HPHT gas condensate reservoir drilled and completed with formate brines, 2001
6 production wells
1-2 Darcy sandstone
BHST: 147oC
TVD : 3,900 m
Hole angle : 45-55o
Fluid density: SG
m x 81/2” reservoir sections
Open hole completions, 65/8” wire wrapped
screens
Lower completion in formate drilling fluid and
upper completions in clear brine
SPE European Formation Damage conference, 5-7 June 2013

14. Huldra – Production of recoverable gas and condensate reserves since Nov 2001 (NPD data)
Plateau production from first 3 wells
- 10 million m3 gas /day
- 30,000 bbl/day condensate
Good sustained production
- 78% of recoverable gas and 89% of
condensate produced by end of Year 7
- Despite rapid pressure decline.....
NPD current estimate of RR:
billion m3 gas
million bbl condensate
Open hole screen completions and single filtrate
SPE European Formation Damage conference, 5-7 June 2013

15. Kvitebjørn field – HPHT gas condensate reservoir drilled and completed with formate brines,
13 wells to date – 8 O/B, 5 in MPD mode
100 mD sandstone
BHST: 155oC
TVD : 4,000 m
Hole angle : 20-40o
Fluid density: SG 2.02 for O/B
m x 81/2” reservoir sections
6 wells completed in open hole : 300-micron single wire-wrapped
screens.
Remainder of wells cased and perforated
SPE European Formation Damage conference, 5-7 June 2013

16. Kvitebjørn– Production of recoverable gas and condensate reserves since Oct 2004 (NPD data)
Good production reported from first 7 wells in million m3 gas /day
- 48,000 bbl/day condensate
Good sustained production (end Y8)
- 37 billion m3 gas
- 17 million m3 of condensate
- Produced 70% of original est. RR by
end of 8th year
NPD : Est. RR have been upgraded
- 89 billion m3 gas (from 55)
- 27 million m3 condensate (from 22)
Note : Shut down 15 months, Y3-5
- To slow reservoir pressure depletion
- Repairs to export pipeline
SPE European Formation Damage conference, 5-7 June 2013

17. Formate brines have been used to complete all of the cased wells in 5 HPHT fields in UK North Sea
Operator
No. of wells
Depth
(meters)
Pressure
(bar)
Temp
(oC)
Wellhead
Brine density
(kg/m3)
Braemar
Marathon 1
(NP)
4,500
701
136
Sub-sea
1.86
Rhum BP 3
4,750
862
149
2.19
West Franklin*
Total 2
7,327
1,154
204
Platform
1.94
Glenelg*
7,385
1,150
200
1.78
Jura
3,935
702
127
2.09
All wells drilled with OBM
* The deepest, hottest and highest-pressured fields in UK North Sea
SPE European Formation Damage conference, 5-7 June 2013

18. Fluid losses from HPHT wells in UK North Sea perforated in formate brines
Field
Kill Pill
Fluid losses during and after perforating
(m3)
Comment
Braemar – 1 well No
2.3
Re-perforation of 18 year old appraisal well. Short flow and then zero losses
Rhum
Yes
0.5
Flowed in first few minutes, then zero losses for 3 days
Glenelg – 1 well
17.7
2m3 on perforating and then 15.7m3 seepage losses
Jura
Yes –over perfs
1.46
Flow stopped within 3 hours
West Franklin
565
F9Y - Pumping brine at intervals during period 29 June-18th July to maintain WHP during 2 perforating runs and fishing
SPE European Formation Damage conference, 5-7 June 2013

19. Braemar field – Production of recoverable gas and condensate reserves since September (DECC data)
Estimated (2003) recoverable reserves produced in full from this single well development by Year 9
Estimated recoverable reserves
billion m3 gas
million m3 condensate
Cumulative 2012
billion m3 gas
million m3 condensate
SPE European Formation Damage conference, 5-7 June 2013

20. Glenelg – Production of gas and condensate since March 2006 (DECC data)
No published reserves information ? Similar to Braemar ?
Highest temperature and pressure reservoir developed in UK North Sea (2006), accessed by single extended reach well
Good initial production
Operator statements :
- «30,000 boe/day capability»
- «500,000 m3/year condensate»
Cumulative Feb 2011
billion m3 gas
million m3 condensate
SPE European Formation Damage conference, 5-7 June 2013

21. West Franklin – Production of gas and condensate from West Franklin/Franklin 2001-11 (DECC data)
No published reserves information. Hottest, highest pressure commercial development in world (2007), accessed by two extended reach wells, F7z and F9y
Excellent initial production
Operator statements :
- « F9y has 40,000 boe/day capability»
- «one of most productive wells in
N. Sea»
- «2.6 million m3/day of gas from F9y»
West Franklin has sustained
the Franklin field output
- > 2.5 billion m3 gas per year from Y6
onwards
Note : 566 m3 of cesium formate brine was pumped into formation around F9Y
SPE European Formation Damage conference, 5-7 June 2013

22. BP Rhum field – largest undeveloped gas field in UK in 2005
45 mD sandstone reservoir
SPE European Formation Damage conference, 5-7 June 2013

23. Rhum field – Production of recoverable gas reserves: December 2005- October 2010 (DECC data)
After nearly 5 years the 3 Rhum production wells had produced 35% of the estimated recoverable gas reserves
Estimated recoverable reserves
- 23 billion m3 gas
Cumulative production Oct 2010
billion m3 gas
Production suspended since late
2010
- EU sanctions against Iran
SPE European Formation Damage conference, 5-7 June 2013

24. Jura – Production of gas and condensate since May 2008 (DECC data)
Estimated (2008) proved and probable reserves of 170 million boe – no published segmentation by hydrocarbon type
Good initial production from 2 wells
billion m3 gas produced during Y2
Cumulative June 2012
billion m3 gas
million m3 condensate
= 46 million boe in total
= 27% production of est. RR after 4 years
SPE European Formation Damage conference, 5-7 June 2013

25. Conclusions – Cat 1 HPHT wells - Drilled and completed in high-angle open hole with formate brines
Tune and Huldra fields produced 100% of recoverable gas and condensate reserves within 10 years – average 3.5 billion m3 gas /well
Gas – 90% in 7-8 years Condensate – 90% in 5-7 years
Provides evidence that drilling and completing HPHT gas production wells in open hole with formate brines can be a successful strategy
Formate Brine Seminar - Stavanger, 22 November 2012

26. Conclusions – Cat 2 HPHT wells - Drilled and completed in open- and cased-hole with formate brines
Kvitebjørn field has produced 70 % of the original estimated reserves by end of Year 8 – despite production constraints
Gas production has been at a steady
6-7 billion m3/year for last 4 years – already
produced 3 billion m3 gas per well
Need more time to see how the production
progresses towards upgraded recoverable
reserves estimate
Good chance to compare durability of open- hole versus cased-hole
HPHT wells ?
Formate Brine Seminar - Stavanger, 22 November 2012

27. Conclusions – Cat 3 HPHT wells - drilled with OBM and completed in cased-hole with formate brines (no pill)
Braemar and Glenelg are both small rich-gas condensate fields drained by single cased wells perforated in formate brines without kill pills. Low brine losses.
Braemar reached original est. RR figure by
Year 9
Glenelg following same gas production track
and already exceeded 2 million m3 condensate
production by Year 5
Formate Brine Seminar - Stavanger, 22 November 2012

28. Conclusions – Cat 3 HPHT wells - drilled with OBM and completed in cased-hole with formate brines (no pill)
West Franklin is a «200 million boe» gas condensate field currently drained by 2 cased wells, perforated in formate brines. Large brine volume pushed into reservoir from well F9y
No cumulative production data available but
was apparently producing >30,000 boe/day
in the 4 years before Elgin gas leak in
March 2012
West Franklin Phase 2 development in
progress
Too early to get a picture of long-term production performance
Formate Brine Seminar - Stavanger, 22 November 2012

29. Conclusions – Cat 3 HPHT wells - drilled with OBM and completed in cased-hole with formate brines+ kill pill
Rhum and Jura are lean gas condensate fields drained by 3 and 2 cased wells respectively, perforated in formate brines with kill pills
Rhum : 35% recovery of gas reserves by Year 5,
before production suspended
Jura : 27% recovery of gas reserves after 4 years
Too early to get a picture of long-term production performance
Formate Brine Seminar - Stavanger, 22 November 2012