What Does Cementation Mean?
Cementation of an oil well is the process of making a cement-water slurry and pouring it down the casing to the desired depth in the borehole. Oil well cementing can be done for various reasons such as zonal isolation to isolate hydrocarbon and water pays or to seal off lost circulation zones. Cementation can also be done to create a hydraulic seal and prevent migration of fluid up the annulus between casing and borehole and to protect the casing to prevent it from leaning on the borehole wall.
Trenchlesspedia Explains Cementation
Cementation is of two types: Primary cementing is done immediately after casing is lowered; secondary cementing refers to any other operation that requires pumping cement into the well either during the drilling or production phase. Since oil and gas wells are drilled in stages, each stage is secured by lowering casings supported by centralizers. The annular space between the casing and the borehole wall is cemented with the cement-water slurry mixed to the desired density. Cementation helps bond and support the casing and protect it from corrosion, seals off zones through which leakage can take place and contaminate groundwater, and restricts movement of fluid between formations.