Chemical Additives for Oil Well Cementing

摘要

Cementing is an extremely important operation in oil well drilling to ensure the integrity of the well, prevent gas and oil migration for an extended period of time. Failure to have adequate cementing will lead to problems that are often catastrophic. Many a times, a revisit of cement integrity is required to diagnose any issues such as formation of micro fractures that will cause fluid or gas migration into the wellbore or to the surface. In such cases where there are issues found with cementing, a remedial cement job is necessary to address the issue. The design of a cement slurry is very important and should be done case by case to ensure trouble-free mixing before pumping and to achieve desired rheology, fluid loss control and thickening time after pumping downhole. A variety of chemicals have been used in cement for the application as retarders, fluid loss control additives, dispersants, gas migration prevention additives and expansion additives. Selection of right chemicals for cement design based on the well profile, off-set well data and other criteria such as temperature and pressure is the key to achieve maximum and long term benefit. There are several reports describing the different chemicals and their application in cementing. The objective of the review is to have an overview chemicals and their performance comparison in cement design based in mechanism of action