Oil-well cement – Specification

IS 8229 - Scope: Key Specifications & Tables

1. Scope Overview

IS 8229 covers procedures for testing hydraulic cement under simulated well conditions, focusing on curing strength and slurry preparation.

2. Well-Simulation Test Schedules for Curing Strength (Table 5)

• Pressure variation tolerance: ±3400 kPa during curing.
• Final temperature tolerance: ±2°C maintained after last value.

3. Slurry Preparation Requirements (Table 4)

IS 8229: Classification & Specifications of Oil-Well Cement

1. Classification of Oil-Well Cement (Classes A to H)

• MgO = Magnesium oxide
• SO3 = Sulphur trioxide
• LOI = Loss on ignition
• C3A = Tricalcium aluminate
• C3S = Tricalcium silicate

2. Physical Requirements (Table 2 Highlights)

IS 8229: Manufacture and Composition of Oil-Well Cement

Key Chemical Formula (Clause 6.72)

[ \text{C}_4\text{AF} + \text{C.F} = (6.72 \times % \text{Al}_2\text{O}_3) - (1.43 \times % \text{Fe}_2\text{O}_3) - (2.85 \times % \text{SO}_3) ]

• Used when the ratio (\frac{% \text{Al}_2\text{O}_3}{% \text{Fe}_2\text{O}_3} < 0.64), indicating formation of iron-alumina-calcium solid solution.

Chemical Composition Limits (Table 1 Highlights)

Physical Requirements (Table 2 Highlights)

| Property | Class A | Class B |

IS 8229: Chemical Requirements for Oil-Well Cement

Key Chemical Formula:

• When Al₂O₃ to Fe₂O₃ ratio (Q) < 0.64, iron-alumina-calcium solid solution forms:

  [ \text{ss} = C_4AF + C.F ]

• Formula involving oxides:

  [ (6.72 \times %Al_2O_3) - (1.43 \times %Fe_2O_3) - (2.85 \times %SO_3) ]

Chemical Limits by Cement Class (Selected):

Notes:

• If C₃A ≤ 8%, max SO₃ = 3%.
• Al₂O₃/Fe₂O₃ ratio affects C₃A content calculation.
• Chemical analysis per IS 4032-1985.

IS 8229 - Physical Requirements for Oil-Well Cement (Table 2 Summary)

IS 8229 - Test Methods Key Points

1. Thermometer Specification (Clause 3.1.6.1)

• Range: 0 to 104℃
• Smallest scale division: ≤ 2℃
• For non-pressure type vessels.

2. Physical Requirements & Test Methods for Oil-Well Cement (Table 2)

3. Well-Simulation Test Schedules (Table 5)

• Pressure: ~20,700 kPa ± 3400 kPa
• Temperature varies by schedule and time (e.g., Schedule 6S: 56℃ at 30 min to 110℃ at 240 min)
• Temperature maintained ±2℃ after final value.

4. Thickening Time Test Schedule (Table 7)

• Temperature and pressure controlled within ±1℃ and ±700 kPa.
• Time-dependent temperature and pressure profiles for schedules 1S to 9S.
• Thickening time measured in Bearden units (Bc), minimum values vary by schedule.

Summary Formula for Compressive Strength (Example for 24h curing at 38℃)

• Class A: ≥ 12.4 N/mm²
• Class B: ≥ 10.3 N/mm²
• Class C: ≥ 13.8 N/mm²

flowchart TD
    A[Test Sample

IS 8229: Sampling and Packaging of Cement

Sampling Procedure (Clause 9.2 & Appendix B)

• Sample size depends on batch size:

• Bags must be randomly selected (ref: IS 4905-1968).

Tolerance on Bag Mass (Appendix B-1 & B-1.1)

• Average net mass per bag ≥ 50 kg.
• Max 5% of sampled bags can have a minus error > 2% of 50 kg (i.e., > 1 kg).
• No bag should have a minus error > 4% of 50 kg (i.e., > 2 kg).

Packaging Material (Clause 9.4.3)

• Packing material to be agreed between manufacturer and purchaser.

Summary Diagram of Sampling Process

flowchart TD
    A[Batch Size] --> B{Batch Size Range}
    B -->|100-150| C[Sample 20 Bags]
    B -->|151-280| D[Sample 32 Bags]
    B -->|281-500| E[Sample 50 Bags]
    B -->|501-1200| F[Sample 80 Bags]
    B -->|1201-3200| G[Sample 125 Bags]
    B -->|>3201| H[Sample 200 Bags]
    C & D & E & F & G & H --> I[Random Selection]
    I --> J[Check Average Mass ≥ 50 kg]
    J --> K[Check Tolerance Limits]

References:

• IS 8229 Appendix B for sampling size & tolerance.
• IS 4905-1968 for random sampling.
• Standard of Weights and Measures (Packaged Commodities) Rules, 1977.

This ensures quality control and compliance with packaging standards.

IS 8229: Marking and Storage of Oil-Well Cement

Marking (Clause 9.1.1)

• Bags/packages may carry the Standard Mark as per BIS rules.
• This mark assures compliance with IS 8229 under strict inspection and quality control.
• Licensing for the Standard Mark is governed by the Bureau of Indian Standards Act, 1986.

Storage (Clause 7 Summary)

• Store cement in dry, moisture-free conditions to prevent deterioration.
• Protect bags from water, humidity, and contamination.
• Use first-in, first-out system to avoid long storage times.
• Avoid exposure to extreme temperatures; for curing above 82°C, refer to schedules 6S, 8S, 9S, 10S (Clause 3.2.4.2).

Key Physical Requirements (Table 2 Extract)

Recommended Curing Schedules for >82°C (Clause 3.2.4.2)

• Use Schedules 6S, 8S, 9S, or 10S for high-temperature curing.

flowchart TD
    A[Marking on Bags] --> B[Standard Mark (BIS)]
    B --> C[Assures Quality & Compliance]
    A --> D[Storage]
    D --> E[Dry, Moisture-free]
    D --> F[Protect from Contamination]
    D --> G[First-in, First-out]
    D -->

IS 8229: Quality Control & Rejection - Key Points

1. Physical Requirements (Table 2 Summary)

2. Compressive Strength (N/mm²) Highlights

• 8-hour curing at 38°C: Class A (1.7), Class C (2.1), Class G (2.1)
• 24-hour curing at 38°C: Class A (12.4), Class C (13.8)
• Schedule 6S and 8S curing also specified for different classes.

3. Sampling & Rejection (Appendix B)

• Sample size depends on batch size:

• Average net mass per bag ≥ 50 kg.
• Random sampling per IS 4905-1968.

4. Slurry Preparation (Table 4)

• Water % by mass varies by cement class (e.g., 46% for A/B, 56% for C, 38% for D/E

Calibration of Testing Apparatus as per IS 8229

1. Calibration Fluid:

• Use Paratone calibration oil with a known viscosity-temperature curve from 5 to 100 Bc.
• Discard Paratone after each use to avoid contamination.

2. Calibration Frequency:

• At least once per year.
• Whenever wear or replacement of metallic parts contacting cement slurry occurs.

3. Calibration of Weights (Table 3):

• New weights must be accurate within half these tolerances.

4. Calibration of Thickening Time Tester:

• Potentiometer mechanism calibrated as per atmospheric pressure consistometer (Clause A-2.2).
• Thermocouples calibrated frequently for temperature accuracy.

5. Thermometer Specification:

• Range: 0 to 104℃
• Smallest scale division: ≤ 2℃

flowchart LR
    A[Start Calibration] --> B{Check Apparatus Condition}
    B -->|Wear/Replacement| C[Recalibrate Immediately]
    B -->|No Wear| D[Annual Calibration]
    C & D --> E[Use Paratone Oil]
    E --> F[Calibrate Weights per Table 3]
    F --> G[Calibrate Thermocouples & Potentiometer]
    G --> H[Discard Paratone Oil]
    H --> I[Calibration Complete]

Summary: Use Paratone oil, calibrate annually or on wear, follow weight tolerances, and ensure temperature devices are accurate within specified ranges.

IS 8229 - Thickening Time Test Schedules: Key Points

1. Thickening Time Definition (Clause 4.4)

• Time elapsed from test start to 100 Bc consistency is the thickening time.
• For high temp. schedules, test may stop at ~70 Bc and extrapolate 100 Bc by plotting.

2. Test Schedules (Clause 4.3.4 & Table 6)

3. Cement Classes & Corresponding Test Schedules (Clause 4.3.4)

IS 8229: Compressive Strength Test Schedules - Key Points

1. Specimen Dimensions & Reporting (Clause 3.3)

• Specimen cross-sectional area: 2,500 mm² (variations ignored unless linear dimension deviates ≥1.6 mm from 50 mm).
• Compressive strength averaged per sample, reported to nearest 70 kPa.

2. Well-Simulation Test Schedules for Curing (Table 5)

• Pressure tolerance: ±3,400 kPa during curing.
• Temperature tolerance: ±2°C after final temperature.

3. Thickening Time Test Schedules (Clause 4.3.4)

IS 8229 - Use of Set-Modifying Agents: Key Formulas & Specifications

Chemical Composition Adjustment (Clause 6.72)

To evaluate the effect of oxides on cement properties, use:

[ \text{Adjustment Factor} = - (6.72 \times % \text{Al}_2\text{O}_3) - (1.43 \times % \text{Fe}_2\text{O}_3) - (2.85 \times % \text{SO}_3) ]

• This formula quantifies the influence of alumina, iron oxide, and sulfur trioxide on cement setting.

Solid Solution Formation (Clause 6.72)

• When the ratio (\frac{\text{Al}_2\text{O}_3}{\text{Fe}_2\text{O}_3} < 0.64), an iron-alumina-calcium solid solution forms.
• Expressed as:
  [ \text{ss} = \text{C}_4\text{AF} + \text{C.F} ]
• This affects the hydration and setting characteristics.

Table 1: Chemical Requirements for Oil-Well Cement (Summary)

Procedures (Clauses 1.2, 2.4, 4.3)

• Detailed procedures for testing and using set-modifying agents ensure consistent cement performance.
• Follow standardized mixing, curing, and testing protocols for oil-well cement.

flowchart LR
    A[Chemical Composition] --> B[Calculate Adjustment Factor]
    B --> C{Is Al2O3/Fe2O3 < 0.64?}
    C -- Yes --> D[Form Iron-Alumina-Calcium Solid Solution]
    C -- No --> E[Standard Hydration]
    D --> F[Modify Setting Time]
    E --> F

Summary: Use the above formula and chemical ratio to assess and modify cement setting behavior with set-modifying

IS 8229: Handling and Safety Considerations - Key Points

1. Operating Instructions (Clause 4.3.1)

• Always follow manufacturer’s operating instructions strictly for safety and proper handling.

2. Temperature and Pressure Considerations (Clause 3.2.4 & Notes)

• Mud densities, surface pressures, and bottom-hole temperatures/pressures are based on field data.

• Bottom-hole pressure ( P_b ) can be calculated as:

  [ P_b = P_s + \rho_m \times g \times h ]

  where:
  ( P_s ) = surface pressure,
  ( \rho_m ) = mud density,
  ( g ) = acceleration due to gravity,
  ( h ) = depth.

3. Physical Requirements for Oil-Well Cement (Clause 3.1, Table 2)

• Thickening time ensures safe handling time before cement sets.
• Compressive strength tests at various curing times and temperatures ensure reliability under downhole conditions.

4. Safety Notes

• Use appropriate PPE and follow handling protocols.
• Store cement and admixtures as per manufacturer guidelines.
• Monitor thickening time to avoid premature setting during pumping.

flowchart TD
    A[Start Handling] --> B[Check Manufacturer Instructions]
    B --> C[Verify Mud Density & Pressure Data]
    C --> D[Calculate Bottom-hole Pressure]
    D --> E[Prepare Cement Mix per Table 2]
    E --> F[Monitor Thickening Time]
    F --> G{Is Thickening Time Adequate?}
    G -- Yes --> H[

IS 8229 - Amendments and References Summary

Key Amendments (Amendment No. 1, June 1989)

• Clause 1.2: Specifies water and cement quantities as per manufacturer recommendations.
• Clause 9.3.1: New clauses inserted after 9.3.1; original 9.4 renumbered as 9.5 (details in amendment document).

Important Tables from Clause 3.1 (Physical Requirements for Oil-Well Cement)

Notes:

• Water: Use as per manufacturer.
• Test Methods: IS 4031-1968* for physical tests.
• Schedules: Compressive strength and thickening times per API Spec 10-1984 (Schedules 1S to 10S).
• Thickening Time: Minimum times vary by schedule; e.g., Schedule 1S = 90 minutes minimum.

Reference to API Specification 10-1984

• Provides test schedules for compressive strength and thickening time.