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Classification of oil well cement

2022-05-17

Oil well cement is specially used for cementing engineering of oil and gas wells, also known as plugging cement. When exploring and exploiting oil or natural gas, the steel casing should be lowered into the well, and then the cement slurry should be injected to cement the casing and the surrounding formation together. Cementing is carried out to isolate the oil, gas and water layers in the formation to prevent them from converging with each other, so as to form a well-isolated oil flow channel from the oil layer to the ground in the well layer.

 

Oil well cement

 

The temperature and pressure at the bottom of the oil well increase with the depth of the well. For every 100 m in depth, the temperature increases by about 3°C, and the pressure increases by 1.0-2.0 MPa. Therefore, the influence of high temperature and high pressure, especially high temperature on various properties of cement, is the most important problem in the production and use of oil well cement. The high temperature causes the strength of Portland cement to decrease significantly,

 

Therefore, oil wells with different concentrations should use different compositions of cement. According to GB 10238-98, my country's oil well cement is divided into nine grades, including ordinary (0), medium sulfate resistance (MSR) and high sulfate resistance (HSR). The scope of application of various grades of oil well cement is as follows:

 

Grade A: It is used when there is no special performance requirement, and it is suitable for cementing from the ground to a well depth of 1830 m. Normal type only.

 

Grade B: It is suitable for use when the downhole conditions require high early strength, and it is suitable for cementing from the surface to a well depth of 1830 m. It is divided into two types: moderate sulfate resistance type and high sulfate resistance type.

 

Grade C: It is suitable for use when the underground conditions require high early strength, and it is suitable for cementing from the surface to a well depth of 1830 m. It is divided into three types: ordinary type, moderate sulfate resistance type and high sulfate resistance type.

 

Class D: It is suitable for use in downhole conditions of medium temperature and medium pressure. It is divided into two types: medium sulfate resistance and high sulfate resistance.

 

Grade E: It is suitable for use in high temperature and high pressure conditions. It is divided into two types: medium sulfate resistance and high sulfate resistance.

 

Class F: suitable for use in ultra-high temperature and high pressure conditions, divided into medium sulfate resistance and high sulfate resistance.

 

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

 

Class J: suitable for cementing in wells of 3 660-4 880 m deep under ultra-high temperature and high pressure conditions.

 

The role of oil well cement

 

The physical performance requirements of oil well cement include: water-cement ratio, cement specific surface area, initial consistency within 15-30 minutes, thickening time at specific temperature and pressure, and compressive strength at specific temperature, pressure and curing age .

 

Its main function is to cement and seal the casing with the surrounding rock formations, isolate the oil, gas and water layers in the formation, and prevent crosstalk from each other, so as to form a well-isolated oil flow channel from the oil layer to the ground in the well. The basic requirements of oil well cement are: the cement slurry must have a certain fluidity and suitable density during the well injection process; after the cement slurry is injected into the well, it should set quickly and reach a considerable strength in a short period of time; the hardened cement slurry It should have good stability, impermeability and corrosion resistance. "

 

The above is the "classification and function of oil well cement" for you. China Haitongyuanda Special Instrument factory is a manufacturer specializing in the manufacture of various Oil Well Cement Testing and Geological Drilling Instrument products, which can solve various instruments required in various geological drilling. Welcome Contact us for more related questions, thank you.