oil well cement

Coromandel Oil Well Cement

  • Oil well cement is considerably different from OPC/PPC.
  • OPC/PPC are used in Construction industry for Structural Concrete.
  • Oil Well cements are used in the form of slurries in conditions encountered in drilling bore hole for oil exploration- not used for structural concrete although it will easily meet the requirement of OPC.
  • Used in Extreme conditions in the form of slurry with requirement such as:
    • slurry must be flowable for hours and then set rapidly
    • slurry is pumped thousands of meters below the surface (>2400 mts)
    • slurry may be exposed to high temperatures (100-250C) at the bottom of the well (up to 300C)
    • slurry may be exposed to high pressure (>20,000 psi)

Oil well cement slurries are used to protect casing from damage from surrounding Water; gives strength & prevents fluid migration (See fig illustration)

Quality Requirements of Oil Well cement (Class- G-HSR) Vs Ordinary Portland/Pozzolana cements (OPC/PPC)

  Oil Well cement Class G OPC/ PPC
Specification Code   IS-8223:1986
API- 10 A Class G HSR*
BIS- 269:2015- OPC
BIS- 1489 (Part I):PPC
Physical Parameters Unit Requirement  
Mix Water % bwoc 44 Based on Consistency
Free Fluid Content % by vol. 5.9 (max) Not Applicable
Compressive Strength after 8 hrs. Curing
i) At 38 0C, Atmospheric Pressure psi 300 (min) (2.1 Mpa) Only at 3,7 & 28 Days Strengths are specified based on Grades
ii) At 60 0C, Atmospheric Pressure psi 1500 (min) (10.5 Mpa)
Thickening Time at 52 0C,
5160 psi raised in 28 minutes
minutes 90 (min) - 120 (max) Not Applicable.
Initial (30 Min) - Final (600 max)
Maximum Consistency
(15 to 30 min. stirring period)
Bc 30 (Bc is a measure of
consistency of cement slurry)
Not Applicable
Chemical Requirements   Class G Requirements OPC/ PPC
Magnesium Oxide (MgO) % 6.0 (maximum) 6.0 ( Maximum)
Sulphur Trioxide (SO3) % 3.0 (maximum) 3.5% ( Maximum)
Iron Oxide (Fe2O3) % - Alumina to Iron ratio 0.66
Min for OPC
Aluminium Oxide (Al2O3) % -
Loss on Ignition % 3.0 (maximum) 4-5% depending on Grade
Insoluble Residue % 0.75 (maximum) 4-5% depending on OPC Grade.
For PPC based on Fly ash Content
Tricalcium Silicate (3CaO.SiO2) % 48 – 65 No Specification
Tricalcium Aluminate
% 3.0 (maximum) Specified only for Sulfate
Resistant cement as<5%
Tetracalcium Aluminoferrite (4CaO.Al2O3.Fe2O3) + Twice the
Tricalcium Aluminate (3CaO.Al2O3)
% 24.0 (maximum) Specified only for Sulfate
Resistant cement as 25% max
Total Alkali content expressed as
Sodium Oxide (Na2O) Equivalent
% 0.75 (maximum) Optional requirement. (0.6%)
Additives % No additive other than Clinker & gypsum permitted 5 % addition of other components in OPC

*American Petroleum Institute Specification – 10 A for Class- G- High Sulfate Resistant (HSR)

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