revision 03 january 1998 * mark of schlumberger silicadrill* - silicate water based drilling fluid...
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Revision 03January 1998
* Mark of Schlumberger
SILICADRILL* - Silicate Water Based Drilling Fluid
Applications
Inhibitive Mechanism
Concerns and Limitations
Engineering
Success Stories
Revision 03January 1998
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SILICADRILL*Drilling fluids based on soluble sodium silicate first introducedin 1930’s.
Based on 20-50% soluble silicates Difficult to control because of high rheologies
Silicate water based fluids further explored by collaborationbetween Mobil, BP Exploration, Shell Research and BW Mud.
Recent silicate systems introduced based on lower concentrations of soluble silicates
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SILICADRILL*
Ability of fluid to reduce shale hydration proportional to :
Increasing silicate concentration. Increasing salt concentration (KCl reducing shale hydration more than an equivalent level of NaCl).
Minimum 10,000 ppm SiO2 required (3% v/v silicate solution).
Optimum at higher pH (approaching pH 12) which additionally prevents fluid gelation. Evidence of synergy with polyalkylene glycols.
Factors Determining Shale Inhibition
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0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
-10 0 10 20 30
Temperature (°C)
Vis
co
sit
y (
cP
)
2.5 : 1 (43%)2.0 :1 (42%)1.6 :1 (48%)2.0 : 1 (42%) + 10% ethylene glycol2.0 : 1 (42%) + 5% KCl
Physical CharacteristicsViscosity / Temperature Profiles for Sodium Silicate Liquors
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SILICADRILL*
0
20
40
60
80
100
9 10 11 12
pH
Rec
over
y (%
)
15
20
25
30
35
40
45
9 10 11 12
pH
Moi
stur
e (%
)
Effect of Fluid pH on Shale Inhibition
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SILICADRILL*Effect of Sodium Silicate Concentration on Shale Inhibition
0
20
40
60
80
100
0 4 8
%
Rec
over
y (%
)
20
24
28
32
36
40
0 4 8
%
Moi
stur
e (%
)
Revision 03January 1998
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SILICADRILL*
20
25
30
35
40
45
50
3%6%
Effect of Salt Concentration on Shale Inhibition
Mo
istu
re (
%)
Sodium Chloride Potassium Chloride
Sodium Silicate
Blank 15ppb 30ppb 54ppb 109ppb 25ppb
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SILICADRILL*Synergy with Polyalkylene Glycol
14
16
18
20
22
24
26
28
0 1 3
STAPLEX 500 (%)
Mo
istu
re (%
)
Revision 03January 1998
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SILICADRILL*-Premix Formulation
Fresh Water 0.662 bbl
Sodium Silicate Liquor 0.255 bbl
KCl 60.0 lb/bbl
IDF-FLR XL 3.0 lb/bbl
IDFLO 9.0 lb/bblOCMA Clay
25% v/v sodium silicate liquor0
50
100
150
200
250
300
-5 0 5 10 15 20 25
Temperature (°C)
Vis
co
sit
y (
cP
)
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SILICADRILL*-Fluid Formulations and Properties
Product ‘Clean’ Fluid ‘Dirty’ Fluid
Fresh Water 0.725 bbl 0.709 bbl
KCl 35.0 lb 35.0 lb
Sodium Silicate 0.110 bbl 0.110 bbl
IDVIS 1.0 lb 1.0 lb
IDF-FLR XL 1.5 lb 1.5 lb
IDFLO 4.5 lb 4.5 lb
PTS 200 2.0 lb 2.0 lb
Hymod Prima - 35.0 lb
BARITE 152.8 lb 125.5 lb
OCMA Clay
Fluid PV YPcP lbs/100 ft2
6 3 Gelslbs/ 100 ft2
pH APIcm3
Na2Omg/l
SiO2
mg/l
Clean 18 17 4 3 4/ - 12.5 11.6 27,900 52,125
Dirty 17 17 5 4 7/ 16 12.5 4.8 24,025 44,625
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Mechanism
Invasion of filtrate (pH 12)
Gellation of invading silicate species in lower pH environment Precipitation of insoluble Ca2+, Mg2+ silicates Chemical dissolution of Al / cementation of clays
Ca2+Mg2+
Mg2+Ca2+
pH 7
Barrier formation at near well bore
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a b c
Transmission Electron Micrographs of Kaolin clay treated with various fluids: a) raw untreated clayb) aged for 3 days at 300 F in distilled waterc) aged for 3 days at 300 F in a 3% aqueous sodium silicate solution at pH 12
Mechanism-Clay Alteration
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Concerns Sensitive to solids contamination
Sensitive to CO2 and H2S contamination Can cause severe gellation and elevated fluid loss if pH is not maintained.
Low shear viscosity is borderline, limiting applications for deviated wells.
Lubricity is poor compared to other water-based muds. Foaming problems identified with IDLUBE XL. Alternative lubricants under review.
Temperature stability limited to wells where BHST is below 230°F. Concern over formation damage in some reservoirs. Depth of invasion of damage not determined.
Elastomer Compatibility Progressive gellation of silicate fluids over long time periods. Not recommended as packer fluids.
Logistics. The volume of sodium silicate stabiliser (C307) recommended for optimum shale control is 8-12 % by volume of the brine phase.
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Temperature Stability
0
5
10
15
20
25
30
35
140 160 180 200 220 240 260
Temperature (°F)
YP API Fluid Loss
Fluid FormulationFresh waterSodium silicate Liq. 10%KCl 40.0 ppbIDVIS 1.3 ppbIDF-FLR XL 1.5 ppbIDFLO 4.5 ppbPTS 200 2.0 ppbHMP 35.0 ppb Barite 97.1 ppb
Mud Weight 11.5 ppg
Effect of Temperature on Fluid Properties
TFL
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-20
20
60
100
140
180
f(
F/d
) H
ard
ne
ss (
%)
QUADRILLSilicateKCl / polymer
Polypak Polypak Polypak PolypakNW6 NW6 MZ3 MZ3 Seal Boot Seal Boot (o-ring) (o-ring)
Elastomer Compatibility
CARBOXYLATED VITON NITRILE HSNNITROXILE
Change in Elastomer Surface Hardness
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-40
-30
-20
-10
0
10
D
ep
th (
%)
QUADRILLSilicateKCl / polymer
Polypak Polypak Polypak PolypakNW6 NW6 MZ3 MZ3 Seal Boot Seal Boot (o-ring) (o-ring)
Elastomer Compatibility
CARBOXYLATED VITON NITRILE HSNNITROXILE
Change in Elastomer Dimensions
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-4
-2
0
2
4
6
8
10
W
eig
ht
(%)
QUADRILLSilicateKCl / polymer
Polypak Polypak Polypak PolypakNW6 NW6 MZ3 MZ3 Seal Boot Seal Boot (o-ring) (o-ring)
Elastomer Compatibility
CARBOXYLATED VITON NITRILE HSNNITROXILE
Change in Elastomer Weight (Swelling / Erosion)
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Lubricity
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 100 200 300 400 500 600 700 800 900
Load (daN)
Fri
cti
on
Co
eff
icie
nt
Blank
3% DP97/016
Frictional Wear Almen-Wieland Lubricity Results
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Contamination PV
(cp)
YP
(lb/100ft2)
pH 6
(cp)
3
(cp)
Gels
(lb/100ft2)
API
(ml)
Na2O
(ppm)
SiO2
(ppm)
None
CO2
5% Carnalite Brine(1)
10% Carnalite Brine(2)
20
24
23
28
19
24
24
36
12.5
11.0
11.9
12.4
5
6
7
19
4
5
5
15
5/8
8/13
6/8
20/30
7.1
38.0
4.6
8.0
25,575
18,600
13,950
6,200
53,000
3,000
18,000
3,750
CO2 and Carnalite Brine
5% Carnalite Brine(1) 1.8 lb/bbl NaOH used to buffer pH to 1210% Carnalite Brine(2) 4.0 lb/bbl NaOH used to buffer pH to 12
Effect of CO2 and Carnalite Brine on Fluid Properties
Properties after heat ageing at 160 °F.
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Contamination PV
(cp)
YP
(lb/100ft2)
pH 6
(cp)
3
(cp)
Gels
(lb/100ft2)
API
(ml)
Na2O
(ppm)
SiO2
(ppm)
None
10 lb/bbl Bentonite
20 lb/bbl Bentonite
30 lb/bbl Bentonite
40 lb/bbl Bentonite
50 lb/bbl Bentonite
60 lb/bbl Bentonite
20
22
24
26
27
31
33
19
17
19
21
26
28
30
12.5
12.4
12.3
12.3
12.1
12.1
11.9
5
5
5
6
6
7
8
4
4
4
4
5
5
6
5/8
5/-
5/6
5/-
6/7
6/-
7/9
7.1
7.4
4.9
5.8
3.9
5.1
3.3
25,575
25,575
24,025
-
23,250
23,250
20,150
53,000
47,250
44,625
-
42,750
41,625
39,000
Drilled SolidsEffect of Bentonite Contamination on Fluid Properties
Properties after heat ageing at 160 °F.
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Contamination PV
(cp)
YP
(lb/100ft2)
pH 6
(cp)
3
(cp)
Gels
(lb/100ft2)
API
(ml)
Na2O
(ppm)
SiO2
(ppm)
None
35 lb/bbl Chalk (Fine)
2.5% Cement Slurry(4)
5% Cement Slurry(4)
20
30
28
32
19
24
30
21
12.5
12.4
13.0
13.0
5
7
13
8
4
5
11
6
5/8
8/10
9/15
6/6
7.1
18.2
4.8
6.1
25,575
23,250
20,150
18,600
53,000
41,250
31,500
23,625
Cement Slurry(4) 50% w/w slurry in fresh water
Cement and ChalkEffect of Cement and Chalk Contamination on Fluid Properties
Properties after heat ageing at 160 °F.
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Contamination PV
(cp)
YP
(lb/100ft2)
pH 6
(cp)
3
(cp)
Gels
(lb/100ft2)
API
(ml)
Na2O
(ppm)
SiO2
(ppm)
None
5% ULTIDRILL
10% ULTIDRILL
20
29
41
19
30
38
12.5
12.4
12.5
5
9
14
4
7
12
5/8
9/15
12/19
7.1
4.3
4.2
25,575
17,050
-
53,000
38,250
-
ULTIDRILL ContaminationEffect of Contamination of an ULTIDRILL Invert Synthetic Fluid
Properties after heat ageing at 160 °F.
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0
20
40
60
80
100
0 5 10 15 20 25 30
NaCl Brine
Mixed Brine (Ca, Mg, Fe)
Reservoir Damage Characteristics
Time (min)
% R
etu
rn P
erm
eab
ility
Return Permeability Studies on Berea Sandstone Cores
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Concentration MonitoringTitration Procedure (NaF - HCl)
0
10,000
20,000
30,000
40,000
50,000
60,000
0 3 6 9 12 15
% Silicate Liq. (v /v)
mg
/dm
3
Si02
Na2O
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SiO2 Adsorption Isotherms
30,000
35,000
40,000
45,000
50,000
55,000
0 10 20 30 40 50 60
Drilled solids (lbs /bbl)
SiO
2 (m
g /d
m3)
Hymod Prima
Bentonite
Silicate Depletion on LGS
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Effective Engineering
Maintain pH with Routine Additions of Caustic Soda. Control LGS with pre-defined Dump & Dilute Programme Maintain SiO2 with Additions of Sodium Silicate Liquor
Pf / Mf Ratio
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SILICADRILL* - Special Considerations
Be aware of the dilution rates. They are very high for SILICADRILL and willrequire some heavy logistics.
System Dilution Coefficient (bbl/ft)
Glycol Mud 0.5 to 1OBM 0.3 to 0.4Silicate Mud 1.5 to 1.7
Elastomer compatibility might be an issue. Please get in contact with our sistercompanies (W&T, Sedco and Anadrill) and make sure that they know we aregoing to use a silicate mud.
SILICADRILL is not tolerant to high LGS concentration. The level should alwaysbe maintained below 5%. So make sure that the adequate solid controlequipment is in place otherwise a heavy dump & dilute approach will have totake place.
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Environmental Impact
Not classified as toxic or dangerous (main hazard attributable to high alkalinity)
Silicates known to form an important resource in the marine food chain.
OSPAR green list - Category ‘A’
UK CNS (Chemical Notification Scheme) category ‘E’ rating
The proposed Preliminary Assessment Information Rule under TOSCA included soluble silicates : The environmental regulatory profile of soluble silicates provides incentive for their preference over more hazardous and more highly regulated alternate materials
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HSE Issues Main hazard of sodium silicate liquor attributable to high alkalinity.
Rabbit dermal irritancy study on silicate drilling fluid indicated no reaction (up to 4 hours exposure).
No field problems reported with respect to skin irritancy of silicate drilling fluid on any well intervals drilled using SILICADRILL*.
PVC slicker suits recommended if heavy contamination expected.
PVC or rubber gloves are recommended
Eye contact must be avoided. Glasses or goggles should always be worn, and preferably face visors while working on the drill floor or in the mud processing area.
Vapours from the drilling fluid will not be a problem, but mists possibly generated from the shale shakers could be irritating to the respiratory tract. Adequate ventilation will keep mist to a minimum, but if mists are generated respiratory protection in the form of a dust respirator type P1 is recommended.
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Shale Hydration
0
5
10
15
20
25
30
35
40
Mo
istu
re (
%)
ULTIDRILL
Silicate-glycol
Silicate
QUADRILL
KCl/IDBOND
VISPLEX
Seawater/PHG
H20 Adsorption from Drilling Fluid
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Shale IntegrityPenetrometer Hardness Profiles
0
300
600
900
1200
1500
1800
2100
2400
2700
0 1 2 3 4 5
ULTIDRILLSilicate-glycolSilicateQUADRILLKCl-IDBONDVISPLEXSeawater/PHG
Fo
rce
(g)
Penetration (mm)
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Current Status
First Dowell Silicate well spudded July 1997 (Canada).
Dowell Canada have used and seen benefits from the lubricant (XE859) First Dowell Silicate Well in the North Sea -a full success Sept 1997.
Engineers’ Training of this new mud system is ongoing at UTC and KTC.
Resources are now in place to extend applications wrt Improved Thermal Stability Improved lubricity and ROP Improved hole cleaning capabilities
Revision 03January 1998
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Future Work
Further evaluation of XE859 (SHELL, Houston). Initial indications that it aided clean up on MI-BP Tester metal surfaces.
Further evaluation of highly modified cross-linked starches. For higher temperature applications or where restrictions on use of PTS 200.
Accretion concerns in silicate fluids formulated with NaCl (GOM). “Anti-accretion” organics to be further investigted, possibly in conjunction with XE859 Lubricant. Dispersants No significant thinning action in solids laiden muds, but still to evaluate in Ca2+/Mg2+ - silicate gelled system. (IDSPERSE XT, DRILLTHIN, D145, TKPP).
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SILICADRILL* Field Experience
Ten hole intervals (July 1997-Jan 1998)
4 X 16” and 4 X12 1/4” intervals offshore Canada
1 X16” and 1 X 171/2” intervals in the Central North Sea
All intervals drilled with SILICADRILL* after extensive laboratory
evaluation of offset well cuttings
- XRD Mineralogical analyses
- Shale inhibition studies cf. ULTIDRILL & QUADRILL
- Evaluation of Accretion tendency
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Drilling with SILICADRILL* in the North Sea
Case History #1: Appraisal Well
* Objective to Drill 12 1/4” section through reactive shales in the central North Sea
* Formation was soft plastic shale stones from 3037 to 7920 ft
* Previous attempts to drill with water based muds in this area were unsuccessful
* S-shaped well trajectory reaching a maximum inclination of 46 °
* SILICADRILL* was chosen ahead of SBMs on environmental grounds
* BHST @ 168 °F, max mud weight 13.1 ppg
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Drilling with SILICADRILL* in the North Sea
Case History #1 (Cont’d): Appraisal Well
* Rig-site evaluation of inhibitive performance using BP cuttings hardness tester
* Excellent wellbore stability: hole in gauge despite 29 days open hole time Mud related NPT= 3.7%
* All Logging and coring completed successfully
* Logging fluid designed using Fann 70 which determined clean mud was required to avoid gelation
* The biggest problems were logistical. The mud was run at higher solids levelsthan programmed (7.3 cf 4%) due to low stocks of silicate liquor
* DUALFLO successfully used to boost low end rheology
Revision 03January 1998
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SILICADRILL* - Offshore North Sea
10
12
14
16
18
20
22
24
3000 3500 4000 4500 5000 5500 6000 6500 7000 7500
MD (ft)
Bit Size (inch)
Hole Caliper (inch)
Case History #1: Hole Caliper Logs Operational SummaryWell Well AInterval 12¼”Field CNS OffshoreDepth 3,040 - 7,320 ftMax. Angle 46°Max. Mud Weight 13.1 ppg
Time Breakdown HoursDrillingCoringLoggingP&ANon Productive
33096
2224856
Drilling Days 18Total Days 29
Cost Efficiency Relative toSBMs
ratio
Cost/ftCost/bblbbl/ft
1.20.781.66
Volume Analysis bblSurface Cuttings/SCE
Dumped11406097
Wellbore FormationLeft in well
153740
Initial hole enlargement associated with physical wellbore instability due to insufficient mud weight (cavings).
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Drilling with SILICADRILL* in the North Sea
Case History #2:
* Objective to Drill 17 1/2” section through 6547ft of reactive shale in CNS
* Decision to drill made by operator following success of #1
* Vertical to 7500 ft building to 22.8° by 8450 ft, TD at 9535 ft
* Open Hole time of 47 days with no wellbore stability
* 17 days drilling time; delays due to non mud related equipment failures, WOW and
wellhead problems
* Largest Volume of hole drilled by Operator in the North Sea to date
* FMP successfully used with this mud system for the first time
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Case History #3: Developmental Wells
* Objective to drill two 16” sections through 7000 ft reactive and dispersive shales
* Formation was mainly siltstone and mudstone
* Maximum hole inclination of 40 °
* SILICADRILL* was chosen on environmental grounds
* STAPLEX 500 was included to maximise inhibitive performance (lab tests)
* BHST 180 °F, max mud weight of 10.1 ppg
Drilling with SILICADRILL* offshore CANADA
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Case History #3: Developmental Wells (Cont’d)
* No wellbore stability issues despite 20+ days open hole
* Observed 30% depletion of K+ and SiO2 whilst drilling initial formation
* Fluids also used to drill 12 1/4” sections successfully
* Silicate depleted and mud converted to salt/ polymer/ carbonate
* Well logged, cored and tested without problem-now producing at a satisfactory rate
* Costs reduced by > two thirds over course of next 4 sections via optimising
fluid (lower silicate, removal of STAPLEX 500 and replacement of IDVIS with prehydrated bentonite gel)
Drilling with SILICADRILL* offshore CANADA
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15
16
17
18
19
20
21
1600 2600 3600 4600 5600 6600 7600
MD (ft)
Ho
le S
ize
Bit Size (inch)
Well East
Case History #3: Hole Caliper Logs Operational SummaryWell Well EASTInterval 16”Field Canadian off shoreDepth 1,690 - 7,707 ftMax. Angle 40°Max. Mud Weight 10.1 ppgMax. BHST 53°C
Time Breakdown HoursDrillingLoggingCasingNon Productive
3721176
123Drilling Days 16Total Days 24
Cost Efficiency Relative to SBMs ratioCost/ftCost/bblbbl/ft (cf 0.2 forSBM)
2.131.531.49
Volume Analysis bblSurface Cuttings/SCE
DumpedC/F to next Interval
4487.11610.82904.0
Wellbore FormationLeft in well
00
Drilling with SILICADRILL* offshore CANADA
Revision 03January 1998
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50
55
60
65
70
75
30,00031,000
32,00033,000
34,00035,000
36,000
37,000
22
23
24
25
26
27
28
29
30
31
22
23
24
25
26
27
28
29
30
31
SiO 2 (mg/L)
KCl (Kg/m 3)
% H2O
Drilling with SILICADRILL* offshore CANADA
Extent of Claystone Hydration with K+, SiO2 Concentration (16” Interval, Well-East)