Well cementing

Well cementing is the process of introducing cement to the annular space between the well-bore and casing or to the annular space between two successive casing strings.

Cement is introduced into the well by means of a cementing head. It helps in pumping cement between the running of the top and bottom plugs.

The most important function of cementing is to achieve zonal isolation. Another purpose of cementing is to achieve a good cement-to-pipe bond. Too low an effective confining pressure may cause the cement to become ductile.

For cement, one thing to note is that there is no correlation between the shear and compressive strength. Another fact to note is that cement strength ranges between 1000 and 1800 psi, and for reservoir pressures > 1000 psi; this means that the pipe cement bond will fail first. This would lead to the development of micro-annuli along the pipe.

A. 0–6000 ft used when special properties are not required.

B. 0–6000 ft used when conditions require moderate to high sulfate resistance

C. 0–6000 ft used when conditions require high early strength

D. 6000–10000 ft used under moderately high temperatures and pressures

E. 10000–14000 ft used under conditions of high temperatures and pressures

F. 10000–16000 ft used under conditions of extremely high temperatures and pressures

G. 0–8000 ft can be used with accelerators and retarders to cover a wide range of well depths and temperatures.

H. 0–8000 ft can be used with accelerators and retarders to cover a wide range of well depths and temperatures.

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