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Oil Well Cement Classification
Jun 11, 2018

The temperature and pressure at the bottom of the well increase with the depth of the well. Each depth of 100 m, the temperature increases by approximately 3°C and the pressure increases by 1.0 to 2.0 MPa. Therefore, the effect of high temperature and high pressure, especially high temperature, on various properties of cement is the most important issue in the production and use of oil well cement. The high temperature effect significantly reduces the strength of Portland cement.

Therefore, different concentrations of oil wells should use different compositions of cement. According to GB 10238-98, China's oil well cement is divided into nine grades, including ordinary (0), medium sulfate resistant (MSR) and high sulfate resistant (HSR) three categories. The scope of use of oil well cement at all levels is as follows:

Class A: Used without special performance requirements, suitable for cement injection from the ground to a depth of 1 830 m. Only ordinary type.

Class B: Suitable for use in downhole conditions requiring high early strength, suitable for cement injection from the ground to a depth of 1 830 m. Divided into two types: medium sulfate resistant and high sulfate resistant.

Class C: Suitable for use in early strength with high downhole conditions, suitable for cement injection from the ground to a depth of 1 830 m. Divided into ordinary type, medium sulfate resistance type and high sulfate resistance type.

Grade D: Suitable for use in downhole conditions with moderate temperature medium pressure, divided into two types: medium sulfate resistant and high sulfate resistant.

Class E: Suitable for use under conditions of high temperature and high pressure, divided into two types: medium sulfate resistant and high sulfate resistant.

Class F: Suitable for use under conditions of ultra-high temperature and high pressure, divided into medium sulfate resistant and high sulfate resistant types.

Grade G and Grade H: It is a basic oil well cement, divided into two types: medium sulfate resistant and high sulfate resistant.

Class J: Suitable for cement injection at depths of 3,660-4,880 m under ultra-high temperature and high pressure conditions.

The physical properties of oil well cements include water-cement ratio, specific surface area of the cement, initial consistency within 15 to 30 minutes, thickening time at a specific temperature and pressure, and compressive strength at a specific temperature, pressure, and curing age. .


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