cementing problems in hpht wells and possible solutions
TRANSCRIPT
India’s only Energy Company in Fortune’s ‘World’s Most Admired’ List
Institute of
Drilling Technology, Dehradun
OISD 28-29 December 2016
Cementing problems in HPHT wells and possible solutions. By Dr Kishori Lal & Parvinder Singh
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Presentation overview
1 Introduction
2 Cementing challenges in HPHT wells
3 HPHT cementing remedy
4 Challenges in Slurry Design
5 Solutions: Criteria adopted
#2 E&P Company in the world
6 Slurry designs
7 Conclusions
Mechanical well integrity during drilling • Isolation of weak & incompetent formations, • Sealing of problematic zones/lost circulation. .
Reservoir Isolation and Protection • Zonal isolation/isolating production from other fluids, preventing migration & restricting fluid movement between formations.
Production Optimization •Optimizing stimulation treatments •Water shut off jobs/ sealing of micro - annulus
Why cementation is important ? ‘’Effective Zonal Isolation for life of well to produce oil and Gas safely and economically’’ .
FG PP
Mud Wt
Dep
th
•Structural support (to bond & support casing, •Protecting the casing from corrosion & shock loads.
Search for new hydrocarbon resources has led to discovery of several High Pressure High Temperature (HPHT) fields world wide.
Drilling, completion, testing and production in HPHT environment are technically complex operations with very high risk and exhibits major HSE issue and are further aggravated with the presence of H2S and CO2.
More challenging in off-shore environments.
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HPHT Classifications
HPHT locations around the globe
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FIG: HPHT Technology Gaps (HPHT Well Summit)
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Cementing challenges in HPHT wells
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Effect of temperature Accurate prediction of temperature Thermal thinning Decrease in rheological properties Strength retrogression
Effect of pressure Slurry density Narrow margin between pore pressure & fracture gradient Small ECD window
Gas migration
Low annular clearance
Degradation of set cement sheath
30”
20”
13 3/8”
9 5/8”
7”
Result : HPHT cement failure
HPHT cementing remedy Accurate estimation of temperature
Monitoring of down-hole conditions
Cementing simulator
Efficient displacement of mud
o Proper mud rheology
o Suitable spacer
o Density train
o Rheological hierarchy
o Wettability change
o Contact time
o Annular velocity Induced stresses during testing
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HPHT cementing remedy
Software assisted prediction of temperature profile
Temperature prediction using API Table
20 40 60 80 100 120 140 160degC
Temp. Profile At 78 min
AnnulusTubular FluidsGeoth.Profile
090
018
0027
0036
00
m
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HPHT cementing remedy
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HPHT cementing remedy
Software-Optimized displacement rate : @ 0.8 m3/min for 15.0 m3 @ 0.7 m3/min for 10.0 m3 @ 0.5 m3/min for 1.3 m3
(Plug bumping) Expected maxim pump pr. : Around 3100 psi
Normal displacement rate : @ 1.0 m3/min for 25.0 m3 @ 0.5 m3/min for 1.3 m3
(Plug bumping) Expected maxim pump pr. : Around 4300 psi
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HPHT cementing remedy
Sample No.
Cement sheath radius for stress check (inches)
Induced stress at depth 3585m (Y=2610679 psi, 𝜗𝜗 =0.33) in PSI
Induced stress at depth 3590m (Y=5801509 psi, 𝜗𝜗 =0.28) in PSI
Remarks
Hoop (𝝈𝝈𝝈𝝈) Radial (𝝈𝝈𝝈𝝈) Hoop (𝝈𝝈𝝈𝝈) Radial (𝝈𝝈𝝈𝝈) 1 3.5 -742 930 -383 1341 Fails at both
depth in tensile. 4.5 -412 600 -42 1000 2 3.5 -561 869 -302 1246 Fails at both
depth in tensile. 4.5 -278 587 3.75 941 3 3.5 -68 667 114 946 Fails at both
depth in tensile. 4.5 77 521 278 781 4 3.5 -210 747 19 1080 Fails at both
depth in tensile. 4.5 -21 558 228 870 5 3.5 -264 773 -14 1122 Fails at both
depth in tensile. 4.5 -59 568 210 897 6 3.5 -266 785 18.6 1151 Fails at both
depth in tensile. 4.5 -58 577 242 927
No cement sample fulfills the
criteria of stress failure.
Complete replacement of
drilling fluid with drill site water
is not suggestible.
Partial replacement facilitates
high pressure testing as well as
minimizes negative effect of
draw down.
Casing Integrity Testing (H/Testing) with water ??
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Challenges of HPHT Slurry Design
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- Long thickening time - Thermal thinning - Low rheology
- Unstable slurry - Settling of heavy wt material - Poor displacement - Channeling
- API Fluid loss > 50 ml - Others: High initial consistency- difficult to prepare & pump
Poor
cementation
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Cement slurry Design Issues for HPHT Wells Efficient slurry design
Cement
Fluid loss control additive
Retarders
Weighting agent
Anti-gas migration
Stopping of strength retrogression
Use of expansive additive for improved cement bond
Stability of cement system
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API CLASSIFICATION OF CEMENTS
Two basic concepts / criteria of classification suggested by API Principal chemical criteria is based on the distribution of main clinker phase Physical criteria is based on physical parameters of cement such as particle size distribution, density and performance tests
API recommendation for oil well cement classification : 6 categories A, B, C, D, G and H Further divided into 3 categories depending upon C3A content: ordinary, moderate & high sulphate resistant 15
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Cement Quality Issue for HPHT wells ONGC procures API Class G HSR Cement for all cementing operations from two Indigenous sources namely, M/s Digvijay Cement M/s Dalmia Cement. Challenges faced during past 2-3 years with Digvijay cement due to, In-consistent behavior High gelation problem in-spite of fulfilling criteria of API. Erratic behaviour while designing slurry for HPHT wells. High consumption of cement additives. Problems sorted out by IDT and filed Patent on
Innovative methodology to ensure quality cement.
Challenges faced during cementing HPHT wells - Case studies
Institute of Drilling Technology
Case study: Poor cementation of few HPHT wells
Asset / Basin
Well Salient Features Observations
K G Basin
A • Depth /Csg. Size: 4823 m / 7” csg with stage collar @ 3797.5 m • BHST/BHCT/BHP: 220 0C/195 0C /14,800 psi • Drg Fluid: WBM, MW: 2.05 •Cmt Slurry Density: 2.15 •Drg depth increased by 400 m, temp increased from 180 0C to 220 0C. •Dynamic loss & activity condition. MW redn from 2.05 to 1.65 •Job carried out at controlled displacement rate.
• Poor CBL / VDL. • Unstable slurry. • Settling of heavy weight material. • No FLCA used. F/L < 50 ml/30 min. due to settling of heavy weight material on sieve during test. • Consistency very low after attaining temp. : chances of settling of heavy weight material after displacement & channeling.
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Cement slurry design: Well A
Conditions
Composition, % BWOC
Results
Sp. Gr. of slurry BHCT, 0C BHP, psi RT, min
2.15 195 14,800 60
W SiO2 Mn3O4
Disp. (CFR3)
FLCA HTR (HR 12)
HTR-E (Comp. R)
ASA (Susp. HT)
GBA (Gas Top
HT)
48 35 30 0.3 0.0 2.0 1.0 0.5 0.2
T T min
F/L ml/30 min
In Cons Bc
Comp. Str. psi
PV/YV F F %
Stability
435/ 453
40/70 20/<10 n.d. 39/< 01 n.d. n.d.
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Thickening time & consistency graph : Well A (Sp. Gr. 2.15, BHCT: 195 0C, BHP: 12,000 psi, TT: 453 min)
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Temperature, 0C
Pressure, Kpsi
Consistency, Bc
Case study: Poor cementation of few HPHT wells
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Asset / Basin
Well Salient Features Observations
K G Basin
B •Depth /Csg. Size: 5450 m / 7” Liner • BHST/BHCT/BHP: 242 0C/220 0C /15,632 psi • Drg Fluid: SOBM, MW: 1.94 •Cmt Slurry Density: 2.20 •Liner stuck during RIH, POOH & re-run without centralizers.
• Poor CBL / VDL • No centralizers • No reciprocation • Wettability change ? • Consistency low after attaining temp. : chances of settling of heavy weight material after displacement & channeling.
Cement slurry design: Well B by Service Provider
Conditions
Composition, % BWOC
Results
Sp. Gr. of slurry BHCT, 0C BHP, psi RT, min
2.20 242 15,632 60
W SiO2 Fe2O3 Mn3O4
Disp. (DO 65)
FLCA (D167)
HTR (D161L)
HTR-E (D121)
ASA (B316)
42 35 25 25 2.5 0.8 9.0 0.8 0.1
T T min
F/L ml/30 min
In Cons Bc
Comp. Str. psi
F F %
Stability
324 44 22 n.d. Nil n.d.
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Thickening time & consistency chart : Well B
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Molds Cured at 2100C for 24 Hrs in curing Chamber .
Shrinkage study at BHST: Particle packing concept minimized shrinkage of set molds
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Way Forward………..
Capability & self-reliance of cement slurries for HPHT wells.
Identification of thermally stable high performance cement
additives and their evaluation - Indigenously - Commercially available To design ultra high density cement slurries (2.1 g/cc to
2.5 g/cc) for extreme temperature conditions (175 0C to 260 0C BHST).
To provide reliable, cost effective and compatible
solutions for better cementations.
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Criteria adopted for HPHT cement slurry
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Particle packing concept: silica (coarse & fine), weighting material (fine/micro-fine)
Control of strength retrogression: use of two blends of silica (fine & coarse)
Weighting material: Use of blend of Hematite & Manganese tetra-oxide, up to 2.25 sp. gr.
Use of non-viscosifying fluid loss additives Use of thermally stable retarders to achieve better thickening
time control Anti-settling agents to prevent settling and to raise the low-end
rheology of cement slurries Effective gas migration control Short transition time (vertical setting) Fluid loss control
Stable Slurry
Slurry Stability
Low strength
Medium strength cement
Effect of slurry stability on annular isolation
High strength cement
Free water
Sp. Gr. 2.31
Sp. Gr. 2.34
Sp. Gr. 2.36
Top
Bottom
Middle
Sedimentation test on cement slurry of sp. gr. 2.35
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Testing conditions
Sp. Gr.
of slurry BHP psi
BHST 0 C
BHCT 0 C
Raising Time min
2.10 10,000 175 150 50
2.20 12,500 200 170 60
2.25 15,000 225 200 60
2.35 18,000 240 225 65
2.50 20,000 260 240 70
Testing conditions are visualised on the basis of future journey of deep HPHT wells.
Desired parameters for HPHT cement slurry
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Properties Parameters
Initial consistency 30 Bc (Max)
Thickening Time 330 ± 30 min
Free Fluid Nil
API Fluid Loss < 50 ml/30 min
Compressive Strength in 24 Hrs
>2000 psi
Stability ± 0.05 g/cc
Gas Migration Study Gas tight slurry
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Slurry design for BHST: 175 0C
Conditions
Composition, % BWOC
Results
Sp. Gr. of slurry BHCT, 0C BHP, psi RT, min
2.10 150 10,000 50
Water Silica Hematite Manganese Tetra Oxide
Dispersant
F/L Control Additive
High Temp.
Retarder
Gas Block Additive
48 25+10 15 15 1.4 0.5 0.8 0.5
Thick. Time min
Initial Consistency
Bc
F/L ml/30 min
Rheology PV/YP
Comp. Str. psi
Gas Migration
Study
Free Fluid
%
Stability
320 30 26 93/20 2500 Gas tight Nil T-2.09 M-2.10 B-2.11
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Consistency graph of cement slurry of sp gr 2.10 (BHCT: 150 0C, BHP: 10,000 psi, T T: 320 min)
Temperature, 0C
Pressure, Kpsi
Consistency, Bc
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Gas migration control
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Gas migration test of cement slurry of sp gr 2.10 at 150 0C (BHCT)
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Slurry design for BHST: 200 0C
Conditions
Composition, % BWOC
Results
Sp. Gr. of slurry BHCT, 0C BHP, psi RT, min
2.20 170 12,000 60
Water Silica Hematite
Mn. Tetra Oxide
Dispersant (Liquid)
Fluid Loss
Additive
Retarder -1
(Liquid)
Retarder -2
(Liquid)
Retarder Enhancer
48 30+10 25 20 4.0 0.8 5.0 2.5 2.5
Thick. Time min
F/L ml/30 min
In Cons Bc
Comp. Str. psi
Free Fluid
%
Stability
345 22 24 2100 Nil T-2.18 M-2.20 B-2.23
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Consistency curve of cement slurry of sp gr 2.20 (BHCT:170 0CBHP: 12,000 psi, T T : 345 min)
Temperature, 0C
Pressure, Kpsi
Consistency, Bc
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Slurry design for BHST: 225 0C
Conditions
Composition, % BWOC
Results
Sp. Gr. of slurry BHCT, 0C BHP, psi RT, min
2.25 200 15,000 60
Water Silica Hematite
Mn. Tetra Oxide
Dispersant Fluid Loss
Additive
Retarder-1 (Liquid)
Retarder-2 (Liquid)
Retarder Enhancer
Gas Block
Additive
44 30+10 25 30 0.8 0.6 5.0 2.5 2.5 0.4
Thick. Time min
F/L ml/30 min
In Cons Bc
Comp. Str. psi
Free Fluid
%
Stability
368 26 30 2300 Nil T-2.23 M-2.24 B-2.26
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Consistency curve of cement slurry of sp gr 2.25 ( BHCT: 200 0C, BHP: 15,000 psi, T T : 368 min)
Pressure, Kpsi
Temperature, 0C
Consistency, Bc
Pressure, Kpsi
Temperature, 0C
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Slurry design for BHST: 240 0C
Conditions
Composition, % BWOC
Results
Sp. Gr. of slurry BHCT, 0C BHP, psi RT, min
2.35 225 18,000 60
Water Silica Mn. Tetra Oxide
Anti Settling Agent
Dispersant Fluid Loss
Additive
Retarder -1
Retarder -2
Retarder Enhancer
Gas Block
Additive
46 35+10 65 0.8 0.7 0.5 0.6 1.2 2.0
0.5
Thick. Time min
F/L ml/30 min
In Cons Bc
Comp. Str. psi
Free Fluid
%
Stability
317 20 30 3100 Nil Stable
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Consistency curve of cement slurry of sp gr 2.35 (BHCT: 225 0C, BHP: 18,000 psi, T T : 317 min)
Temperature, 0C
Pressure, Kpsi
Consistency, Bc
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Slurry design for BHST: 260 0C
Conditions
Composition, % BWOC
Results
Sp. Gr. of slurry BHCT, 0C BHP, psi RT, min
2.50 240 20,000 70
Water Silica Mn. Tetra Oxide
Anti Settling Agent
Dispersant Fluid Loss
Additive
Retarder -1
Retarder -2
Retarder Enhancer
46 35+10 100 0.8 0.8 1.0 0.8 2.3 2.0
Thick. Time min
F/L ml/30 min
In Cons Bc
Comp. Str. psi
Free Fluid
%
Stability
309 35 20 3000 Nil Stable
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Consistency graph of cement slurry of sp. gr. 2.50 ( BHCT: 240 0C, BHP: 20,000 psi, TT: 309 min)
Consistency, Bc
Pressure, Kpsi Temperature, 0C Temperature, 0C
Pressure, Kpsi
Consistency, Bc
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Performance & Testing Conditions
Specification: (Temp range 140-170 deg C BHCT)
Parameter Specification Unit
Pressure 12500 Psi
Temperature BHST/BHCT 200/ 170 Deg C
Raising Time 60 Minute
Initial consistency (Max) 20 BC
Sp. Gravity 2.0
Thickening Time 300±30 Minute
API Fluid loss ( Max) <50 Ml/ 30 minutes
Compressive strength after 48 hrs. ( Min) 2000 Psi
Free fluid Nil
Slurry Stability and BP test ( density difference Top & Bottom ) ( Max)
0.05 g/cc
Gas migration test Shall be gas tight slurry
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Performance & Testing Conditions
Specification: (Temp range 170-200 deg C BHCT)
Parameter Specification Unit
Pressure 15000 Psi
Temperature BHST/BHCT 230/ 200 Deg C
Raising Time 70 Minute
Initial consistency (Max) 25 BC
Sp. Gravity 2.35
Thickening Time 330±30 Minute
API Fluid loss ( Max) <50 Ml/ 30 minutes
Compressive strength after 48 hrs. ( Min) 2000 Psi
Free fluid Nil
Slurry Stability and BP test ( density difference Top & Bottom ) ( Max)
0.05 g/cc
Gas migration test Shall be gas tight slurry
43
Performance & Testing Conditions
Specification: (Temp range 200-230 deg C BHCT)
Parameter Specification Unit
Pressure 18000 Psi
Temperature BHST/BHCT 255/ 230 Deg C
Raising Time 70 Minute
Initial consistency (Max) 25 BC
Sp. Gravity 2.5
Thickening Time 360±30 Minute
API Fluid loss ( Max) <50 Ml/ 30 minutes
Compressive strength after 48 hrs. ( Min) 2000 Psi
Free fluid Nil
Slurry Stability and BP test ( density difference Top & Bottom ) ( Max)
0.05 g/cc
Gas migration test Shall be gas tight slurry
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Comparative study: Digvijay v/s Dalmia
Condition Sp. Gr. Of Slurry BHST (˚C) BHCT (˚C)
BHP (psi) RT (Minute)
2.5 255 230 18000 70
Composition- % BWOC Cement (100gm)
Water Silica Mn3O4 Dispersant CFR-3
F/loss Additive H-413
Retarder-1 FDP-742
Retarder-2 Comp-R
Retarder-3 HR-12
Anti Settling S/ HT
Digvijay 46 40 100 0.8 0.8 2.3 2.0 0.8 0.8
Dalmia 46 40 100 0.8 0.8 1.7 1.3 -- 0.8
Results Cement (100gm)
TT F/Loss Ml/ 30 Min
Initial BC CS @ 24 Hrs
Free Fluid Stability Rheology Pv/Yp
Digvijay 309 30 30 3300 Nil ND 120/ 31 Vc - 10.2 fps
Dalmia 330 36 25 2800 Nil ND 125/ 25 Vc - 8 fps
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Comparative study: Dalmia v/s Dyckerhoff
Condition Sp. Gr. Of Slurry BHST (˚C) BHCT (˚C)
BHP (psi) RT (Minute)
2.5 255 230 15000 70
Composition- % BWOC Cement (100gm)
Water Silica Mn3O4 Dispersant CFR-3
F/loss Additive H-413
Retarder-1 SCR-742
Retarder-2 Comp-R
Anti Settling S/ HT
Digvijay 44 40 100 0.8 0.8 1.6 1.2 0.8
Dalmia 44 40 100 0.8 0.8 1.6 1.3 0.8
Results Cement (100gm)
TT F/Loss Ml/ 30 Min
Initial BC CS @ 24 Hrs
Free Fluid Stability Rheology Pv/Yp
Dalmia 330 36 25 2800 Nil ND 125/ 25 Vc - 8 fps
Dyckerhoff 282 40 15 3000 Nil ND 78/ 17 Vc - 6 fps
Typical T T consistency chart of SG 2.5 at 230 Deg C
Typical consistency Graph @ 2.50 SG
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Temperature, 0C
Pressure Consistency Bc
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New Addition : SGSA
MACS-II
a) Evaluates Static Gel Strength (SGS) dynamically.
- by measuring torque in accordance with the resistance in shear of the paddle with the cement slurry.
b) Speed Range: ~0.2 deg/min (0.000556 rev/min) to 150 rev/min. c) Maximum Temperature: 600 °F (315.6 °C) d) Maximum Pressure: 30,000 psig (206.8 M Pascal) e) 100 to 500 lb/ 100ft2 within 45
minute indicate gas tight slurry.
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New Addition : SGSA
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New Addition : HT-UCA
a)The compressive strength,
along with temperature and
pressure, are monitored as a
function of time for the
purpose of providing a
strength history of a setting
cement slurry.
b) Max. Temperature: (260 °C)
c) Max. Pressure: 20,000 psi
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New Addition :HT-UCA
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Highlights of Cementing (R&D) TG,IDT
1. IDT identifies that high temperature thinning and high temperature settling of cement slurries are most critical parameters in designing cement slurries for 175-260 0C and of Sp. Gr. 2.10 - 2.50.
2. The problems of gas migration, ultra HPHT fluid loss and high temperature settling were found to be excellently controlled with the combination of particle packing with fine silica along with Hematite and Manganese Tetra-oxide.
3. Such a design is able to arrest gas migration and sedimentation even at ultra high temperature of 260 0C.
4. The particle range of 0.25-100 microns fine silica is critical to performance.
5. The suggested systems have synthetic retarders, non-viscosifying fluid loss control additives with a blend of Hematite and Manganese tetra-oxide to obtain best results.
6 IDT has inducted two new state of art technology i.e SGSA and HT-UCA.
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Summary
Determine the Parameters as per API Recommended Practice 10B-2, Second
Edition April 2013 or as amended from time to time.
Fluid loss to be determined at bottom hole circulation temperature (BHCT)
&1000 psi , performing conditioning with Stirred fluid loss cell /Non stirred
Fluid- loss Cell using pressurized consistometer at the test temperature.
Determine the Rheology, Free fluid after raising the slurry to BHCT and cool
down to 88 deg C.
Sensitivity testing with ± 5% retarder concentration (same for retarder aids)
and ± 0.25Ib/gal (0.03 gm/cc) slurry density.
Gas Migration Test should be conducted on SGSA
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Conti----
For strength retrogression additives 40% (Min) to be used.
Mn3O4(Manganese Tetra Oxide) miscible/dispersible in water without settling
/sedimentation to achieve the desired parameters is required.
Initial consistency to be recorded after 5 min conditioning at ambient
temperature.
Break required after raising temperature & pressure for 45 min .Hump shall
not elapse more than 30 sec from the time motor is switched on.
Computer software assisted planning helps to optimize the operation.
Rheological hierarchy has to be maintained.
Casing integrity testing is suggested with partial fluid replacement with water.
Thanks
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