www.formatebrines.com

Formate brines

Formate brines Important applicational niche in deep HPHT work

Low-solids fluids for deep HPHT gas well constructions

• Reservoir drill-in

• Completions

• Workovers

• Packer and long-term well suspensions

A mature field proven technology used in deep gas fields since 1995

13Cr tubular from BP High Island well : 6 years exposure to

11.5 ppg formate brine packer fluid @175 oC

Conventional formate drilling fluid formulation -in field use since 1993 and good to 160oC

Component Function Concentration

Formate brine

DensityLubricity

Polymer protectionBiocide

1 bbl

XanthanXanthanViscosity

Fluid loss control 0.75 - 1 ppb0.75 - 1 ppb

Ultralow vis PAC and modified Ultralow vis PAC and modified starchstarch

Fluid loss control 3 or 4 ppb of each3 or 4 ppb of each

Sized calcium carbonateSized calcium carbonate Filter cake agent 20 ppb20 ppb

KK22COCO33/KHCO/KHCO33Buffer

Acid gas corrosion control 0 – 6 ppb0 – 6 ppb

Simple, effective, non-damaging reservoir drill-in fluid

Used to drill entire wells, top to bottom, in sensitive environments (e.g. Barents Sea)

Formate-based drilling fluids

W-Cluster

Z2

Z6

Z5Z7

Z4

5000'

10000'

15000'

18000'

1995 – Formate brines used for first time by Mobil to drill and work over deep gas wells, onshore, northern Germany

Walsrode field – onshore, high-angle slim hole wells Z1, Z5, Z6 and Z7

TVD : 4,450-5,547 metres Reservoir: Sandstone 0.1-125 mDBHST : 315oF (157o C) Section length: 345-650 metres

42 deep HPHT gas fields developed using

potassium and cesium formate brines, 1995-2011 Country Fields Reservoir Description

Matrix

type

Depth, TVD

(metres)

Permeability

(mD)

Temperature

(oC)

Germany (7) Walsrode,Sohlingen

Voelkersen,I dsingen,

Kalle, Weissenmoor,

Simonswolde

Sandstone 4,450-6,500 0.1-150 150-165

Hungary (2) Mako , Vetyem Sandstone 5,692 - 235

Kazakhstan (1) Kashagan Carbonate 4,595-5,088 - 100

Norway (10) Huldra ,Njord

Kristin,Kvitebjoern

Tune, Valemon

Victoria, Morvin,

Vega, Asgard

Sandstone 4,090-7,380 50-1,000 121-200

Pakistan (2) Miano, Sawan Sandstone 3,400 10-5,000 175

Saudi Arabia (7) Andar,Shedgum

Uthmaniyah

Hawiyah,Haradh

Tinat, Midrikah

Sandstone

and

carbonate

3,963-4,572 0.1-40 132-154

UK (12) Braemar,Devenick

Dunbar,Elgin

Franklin,Glenelg

Judy, Jura, Kessog

Rhum, Shearwater

West Franklin

Sandstone 4,500-7,353 0.01-1,000 123-207

USA (1) High Island Sandstone 4,833 - 177

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

Cesium formate brine produced by Cabot Specialty Fluids 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

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

Key applications for cesium formate brine

Drill-in and completion fluids for enhancing the safety and economics of HPHT gas field developments

Cesium formate brine - Field applications

277 jobs in 50 field developments* (see website for list)

•Drill-in - 33

•Completions - 156 (131 WB and 25 OB) - as a brine and in LSOBM formulations (up to 1.60 SG)

- outstanding as HPHT perforating kill pill (Visund, Braemar, Judy, Rhum)

•Workovers (27) and miscellaneous (61) Includes diverse uses:

- Well suspension

- Well testing

- Stuck-pipe release pill (OBM drilling)

- Melting hydrate plugs

- Also now being used in deep shale gas wells in USA

* not all HPHT

Shell UK was the first user of cesium formate brine – Shearwater field, September 1999

17.20 – 18.86 ppg completion and

workover fluid

•Shearwater field – UK North Sea

•Gas condensate reservoir

•15,000 psi

•BHST 365oF

10 cesium formate jobs to date

Use of cesium formate by Total as HPHT completion and workover fluid

Initial use as18.2 ppg completion fluid in 8 Elgin/Franklin wells

•World’s largest HPHT field

•Gas condensate reservoir

•16,000 psi @ 20,000ft

•BHST 200oC

•140,000 bbl/day of condensate

•13 million m3 gas /day

Cesium formate brine has now been used by TOTAL in 34 HPHT well construction operations in 8 deep gas fields over the period 1999-2010

Some HPHT perforating jobs

• Glenelg 22/30c-GLA - 195oC- No perforating pill.

- Losses 2m3 on perf, 15.7m3 seepage after

• Kessog 30/1c-09 - 170oC- 200m blocking pill column above perforation zone

- 45min – 0.36m3 lost

- Next hour – 0.22m3 lost

- Next 7.5 hours – 0.6m3 lost

• Jura 1 3/15-10 - 127oC - Blocking pill over perfs

- 1.5 m3 lost over 15 hours post perforation

• Braemar 16/3b-8z - 135oC- No perforating pill

- Perf losses 14.5 bbl

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

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

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

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

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

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

• 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

Cesium formate brine first used as a combined drill-in and completion fluid in the Huldra field, 2001

Huldra – drill-in, logging and completion times (days) with cesium formate brine in well

A-4

(189 m )

A-5

(263 m)

A-6

(344 m)

A-8

(257 m)

A-9

(230 m)

A-11

(336 m)

Average

(231 m)

Drill-in 5 8 20 15 7 11 11

Logging Logging 0 3 1 7 3 2 2.7

Lower completion

11 6 5 6 5 5 6.3

Upper Upper completion completion

4 5 4 4 9 4 5

Total 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

Huldra – Fluid losses while drilling (cubic metres)

A-4

(189 m )

A-5

(263 m)

A-6

(344 m)

A-8

(257 m)

A-9

(230 m)

A-11

(336 m)

Average

(231 m)

With cuttings 2.6 16.4 48 9.6 23.8 17.7 19.7

Other surface 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 Well displacements displacements

5.6 28.3 12.8 24.3 11 15.7 16.3

Tripping Tripping 6.5 7.2 6.3 3.6 1.6 2.8 4.7

TOTAL TOTAL 23.8 66 123.6 39.7 48.4 53.3 59.1

Huldra – Production of recoverable gas and condensate reserves since 2001 (NPD data)

Plateau production from first 3 wells

- 10 MM m3 gas /day

- 30,000 bbl/day condensate

80% of hydrocarbon reserves produced

by Year 6

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

Source : Norwegian Petroleum Directorate- Fact Pages - November 2009

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

years

Source : Norwegian Petroleum Directorate- Fact Pages - November 2009

• 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

Seven years of cesium formate brine use as combined drill-in and completion fluid in Kvitebjoern field, 2004 -present

A few of the highlights from Kvitebjoern

Kvitebjoern well

Completion time

(days)

A-4 17.5

A-5A-5 17.8

A-15 14.8

A-10A-10 15.9

A-6A-6 12.7 *

Fastest HPHT well completion in the North Sea

“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)”

Operator comments after well testing (Q3 2004 )

The Well PI was almost double the target

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)

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)

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)”

Economic benefits from use of cesium formate brine in deep gas field developments

Operational efficiencies Lower NPT Lower costs • No differential sticking

• No well bore instability*

• Pipe and casing running speeds are fast

• Mud conditioning and flow-check times are short

• Displacements simplified, sometimes eliminated

Formate drilling fluid = formate completion fluid

* 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”

Duration of flow back(minutes)

Fluid Gain (bbl)

30 0.8

15 0.56

20 0.44

30 0.56

Flow check fingerprint for a Huldra well

Cesium formate drilling fluids – some important features that impact on nuclear logging

The extreme photoelectric effect of the cesium formate filtrate provides the log interpreter with valuable information regarding invasion, thus porosity and net reservoir.

« Lithology » RhoB

[g/cc]

Pe

[barns/e]

RhoE

[g/cc]

Salt water 1.09 0.807 1.185

Oil 0.85 0.119 0.948

Clean Sandstone 2.31 1.75 2.33

Shaly sandstone 2.39 2.70 2.41

Shale 2.65 3.42 2.65

2.03 s.g Cs/K

formate 2.03 163 1.953

Cesium formate drilling fluids – some important features that impact on nuclear logging

Filtrate is mobile : gravity segregation over time and replacement by hydrocarbon phases

Effect of invasion and time lapse: From left to right, formation density (ROBB), medium deep resistivity (P16) and deep resistivity (P40). LWD drill pass data represented by red curves and ream pass represented by black curves.

Logged Pef and observation of filtrate movement can be

used to define permeable sands in gas reservoirs (SPE 105733)

“Using the 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” Berg et al, SPE 105773

Log responses from drill-pass (P16_1) and ream-pass (P16_2) provide a powerful technique for defining permeable intervals (SAND_FLAG).

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)

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

Summary

10 years of drilling with cesium formate brine has shown that it

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