In shallow and low temperature wells, accelerator is generally required to speed up the cement hydration process and reduce cement set time. Sometimes it is also used to reduce thickening time caused by other cement additives such as fluid loss control agents and dispersants. It generally takes longer time for cement to set at low temperature.

Dispersants lower slurry viscosity and pumping friction and improve fluid loss; anti-settling agents prevent free water and sedimentation to keep slurry stable.

Foams formed while mixing cement slurry cause many problems such as lower and wrong density reading, poor particle wetting and hydration efficiency, and pumping difficulties due to pump cavitation and loss of suction. Defoamer or antifoaming agent is often required in cement slurry to avoid problems described above, especially for Latex Slurries.

Spacers are engineeringly designed to assist mud removal by acting as a buffer between cement slurry and drilling fluids with specific density and rheological properties. Together with chemical washes, it can be pumped as either turbulent or laminar flow. Some spacers also provide good fluid loss control. Specialty spacers sometimes contain additives, which help to improve cement bonding with casing and formation rocks.

Hydration time and cement set period are critical for well cementing design. Retarders are generally utilized in cement slurry to control cement thickening time to reduce job risks especially at medium to high temperature applications.

Selection of fluid loss control additives is very important for cementing job design. Most fluid loss control agents affect other properties of cement slurry such as rheology, retardation, and cement set strength. Comprehensive laboratory testing is generally required for selection of fluid loss control agent especially at high temperatures.

The primary function of the gas migration control additive is to prevent gas migration, improve cement quality, and avoid gas channeling, thereby avoiding cementing failures and wellbore instability to ensure the safe and efficient cementing operations of oil and gas wells.

Extenders increase slurry volume without excess water loss and with adequate strength; weighting materials provide the high hydrostatic pressure needed for unstable or high-pressure formations.

Extenders let slurries take extra water without separation, lowering density and aiding fluid-loss control; anti-corrosion agents protect cement from CO2/H2S attack.

Changes in down-hole conditions such as temperature, pressure can induce sufficient stress to destroy the integrity of the cement sheath. Flexible agents, durable agents and expanding agents are typically utilized to minimize the risks of cement sheath failures and compensate for the volumetric shrinkage of the cement during the setting process by generating large-volume crystalline hydration products.

The thixotropic cementing slurry is a very good solution for loss circulation while cementing. Fluid losses to fractures, fissures or highly permeable zones during cementing operations generally result in pumping large volume of cement slurries, cement fallback and remedial treatment.