The principle of cementing admixtures mainly includes the following aspects:
Mechanism of action: Cementing admixtures delay the initial coagulation of cement hydration through adsorption, dispersion, wetting and other effects, thereby adjusting the performance of cement slurry. For example, organic surfactant retarders delay the setting time of cement through these mechanisms of action.
Chemical composition: Cementing admixtures can be divided into polymers, surfactants and inorganic salts. These chemical substances can improve the performance of drilling fluid or cement slurry and meet the requirements of cementing construction. For example, polymer admixtures increase the viscosity of drilling fluid by increasing the content of high molecular weight substances, surfactant admixtures improve rheology by reducing surface tension, and inorganic salt admixtures adjust the performance by changing the ion concentration of the solution.
Application scenario: Cementing admixtures are widely used in cementing projects of oil and gas wells and water wells. In cementing of oil and gas wells, admixtures are used to improve the stability and strength of cement slurry, prevent oil, gas and water from channeling, and improve mining efficiency. In water well cementing, admixtures are used to control the setting time of cement slurry, prevent water from entering the cement slurry, and ensure the long-term use of the water well. 2. Specific types: Common cementing admixtures include accelerators, dispersants, thickeners, etc. Accelerators such as chloride salts and organic compounds accelerate the setting and hardening of cement through the common ion effect and salt effect. Dispersants such as lignin sulfonates and their derivatives are used to improve the rheology and suspension ability of cement slurry. Thickeners increase the viscosity and shear force of drilling fluids by increasing the content of polymer substances.
