A lubricating mud consisting of water, clay, pozzolans and other materials is used
to facili-tate drilling of oil, gas, water and geothermal wells. This lubricating mud is
forced out through the bottom of the drill casing and the space between the well bore and
the casing is cemented to prevent the intrusion of corrosive waters and other contaminants
into the well.
Why Perlite Cement?
Well cementing materials such as diatomaceous earth, pozzolan, fly ash and glass
beads do not have the lightweight properties exhibited by perlite concrete unless
concentra-tions of bentonite or gel, as it is referred to, are added to the cement. A
disadvantage of large concentrations of gel is that they are not com-patible with heat.
Because perlite cement is not affected by heat and little material is lost in cementing
operations due to its ability to bridge voids, perlite cement provides a more effective
and less costly well cement. The dry weight of perlite is only 8 lb/ft3 (128
kg/M3) as opposed to 25-100 lb/ft3 (400-1600 kg/M3) - the
dry weight of the other materials.
Advantages of Using Perlite Well Cement
- Lighter density
- Aids in bridging
- Heat compatible
- Lower costs
- Insulating qualities