What is Class G Cement?

Class G cement is a type of oil well cement specifically designed for use in drilling operations to provide zonal isolation and structural integrity in oil and gas wells. It is classified under API (American Petroleum Institute) standards and is widely used for cementing casing and liners in wells drilled for oil, gas, and geothermal energy.

Class G cement is primarily composed of Portland cement clinker blended with additives that enhance its performance under high-temperature and high-pressure conditions typically encountered in deep wells. It offers excellent compressive strength, low permeability, and good resistance to chemical attack, making it suitable for cementing across a wide range of geological formations.

The manufacturing process of Class G cement involves grinding clinker with gypsum and other performance-enhancing additives to meet the stringent API specifications. Depending on the drilling requirements, it can be modified with additives such as retarders, dispersants, and extenders to tailor properties like setting time, viscosity, and density.

In well construction, Class G cement forms a solid barrier between the casing and the borehole, preventing fluid migration, supporting the casing, and protecting the wellbore from collapse. It also plays a crucial role in isolating different pressure zones and preventing contamination of underground water reservoirs.

While Class G cement is robust and durable, proper handling and mixing procedures are essential to maintain its performance characteristics. The dry cement powder can be irritating to skin and eyes, and inhalation of dust should be avoided by using adequate personal protective equipment.

USES AND APPLICATIONS

INDUSTRIES

Class G cement is extensively used in:

• Oil and gas well cementing operations
• Geothermal well construction
• Deep and high-pressure well cementing
• Zonal isolation and casing support in drilling projects