H. 0–8000 ft can be used with accelerators and retarders to cover a wide range of well depths and temperatures.
API cement grades A, B and C correspond to ASTM type I, II and III.
The tests should be conducted on a sample that represents the cement to be used on the job site.
Calcium chloride, under the right conditions, tends to improve the compressive strength and significantly reduces the thickening and setting time.
The differing rates of expansion and contraction could result in the casing pulling away from the cement and lead to the formation of micro-annuli.
It also has the ability to affect the cement rheology, the compressive strength development, produce shrinkage by 10–15%, increases the permeability with time, and lowers the sulphate resistance.
They work by one of 4 main theories; Lignosulphonates: Wood pulp derived polymers.
It absorbs into the C-S-H gel and causes a change of morphology to a more impermeable structure.
Such compounds are not commonly used due to the degree of retardation being very sensitive to variation of concentration.
Increases slurry yield – reduces the amount of cement required to produce a given volume.
Low-density aggregates – Materials with densities less than Portland cement (3.15 g/cm3) Hollow Glass Microspheres - engineered high strength (unicellular) low density (average true densities as low as 0.3 g/cc for the medium strength versions), non porous hollow glass spheres, usually below 40 μm in average particle size, enable hydraulic cement slurries as low as 8 PpG (960 Kg/m^3) Gaseous extenders – Nitrogen or air can be used to prepare foam.
Bentonite – this is added in conjunction with additional water, used for specific weight control but makes poor cement.
The high surface area increases the water demand to get pumpable slurry.
Powdered coal – Can be used to obtain a slurry with a density as low as 11.9ppg, 12.5–25 lbs per sack are usually added.
They increase the viscosity of the aqueous phase and decrease the filter cake permeability.
These are cement slurries that upon entering the formation begin to gel and eventually become self-supporting.