Cement slurry is a pumpable mixture of cement, water, and, when required, specifically designed additives. It is prepared in a fluid state so it can be transported and placed before it hardens. In the oil and gas, geothermal, and water well industries, cement slurry is pumped into the wellbore to fill the annular space between the casing and the surrounding formation, or to perform other cementing operations. In construction applications, cement slurry may also be used for grouting, sealing, or other specialized purposes where a flowable cement mixture is needed.
The primary purpose of a cement slurry in well cementing is to provide zonal isolation, support and protect the casing, and help prevent the migration of fluids between geological formations. The slurry is formulated to have specific properties, such as density, viscosity, pumping time, and compressive strength development, so it can be placed effectively under the temperature and pressure conditions of the well. After placement, the slurry undergoes hydration, a chemical reaction between cement and water, and gradually hardens into a solid mass known as set cement.
The composition and performance of a cement slurry can vary significantly depending on the application. Additives may be used to control setting time, fluid loss, density, strength, gas migration, or other characteristics. Regardless of the formulation, a cement slurry is fundamentally a mixture of cement and water engineered to remain fluid long enough for placement and then solidify to perform its intended structural and sealing functions.
Petroleum cement slurry is a specially formulated mixture of hydraulic cement, water, and selected additives used in oil and gas well cementing operations. The cement slurry pumped into a wellbore during drilling and completion activities to perform functions such as casing support, zonal isolation, and well integrity protection. The cement used is commonly oil well cement manufactured to meet the demanding temperature, pressure, and chemical conditions encountered in petroleum wells.
