Oilwell Cement

A basic well cement intended for use as a basic slurry from surface to roughly 8,000 ft (2,440 m) as manufactured, and the most widely used class because it accepts accelerators and retarders to cover a broad depth and temperature range. Supplied in moderate and high sulfate-resistant grades.

A basic well cement similar in chemistry to Class G but ground coarser, giving a higher slurry density and lower water requirement; also used as a basic slurry to about 8,000 ft and modified with additives for deeper service. Common in regions favoring a coarser, higher-density base cement.

A general-purpose well cement intended for use from surface to about 6,000 ft (1,830 m) when special properties are not required; comparable to ordinary Portland cement and available only in the ordinary (O) grade.

A high-early-strength well cement for use from surface to about 6,000 ft where rapid strength development is needed; produced with higher tricalcium silicate content and finer grind, and available in ordinary, moderate, and high sulfate-resistant grades.

Cement grades manufactured with limited tricalcium aluminate to resist degradation by sulfate-bearing formation and ground waters. High Sulfate-Resistant (HSR) caps C3A more tightly than Moderate Sulfate-Resistant (MSR), and is specified where corrosive downhole environments are expected.

A well cement for use from surface to about 6,000 ft when moderate or high sulfate resistance is required, offered in MSR and HSR grades. Used where Class A chemistry is acceptable but sulfate protection is also needed.

Cement systems and blends formulated for low-density placement and weak or depleted formations, including the API Class L-type specialty designation; selected to reduce hydrostatic pressure on fragile zones and limit losses during cementing.