PERLITE FOR USE IN WELL CEMENTS---SCHUNDLER PRODUCT GUIDE

Perlite is not a trade name but a generic term for naturally occurring siliceous volcanic rock. The distinguishing feature which sets perlite apart from other volcanic glasses is that when heated to a suitable point in its softening range, it expands from four to twenty times its original volume.

This expansion process is due to the presence of two to six percent combined water in the crude perlite rock. When quickly heated to above 1600^o F (870^o C) the crude rock pops in a manner similar to popcorn as the combined water vaporizes and creates countless tiny bubbles in the softened glassy particles. It is these tiny glass-sealed bubbles which account for the amazing lightweight and other exceptional physical properties of expanded perlite.

The expansion process also creates one of perlite's most distinguishing characteristics: its white color. While the crude perlite rock may range from transparent to light gray to glossy black, the color of expanded perlite ranges from snowy white to grayish white.

Expanded perlite can be manufactured to weigh from 2 lbs/ft³ (32 kg/m³ ) to 15 lb/ft³ (240 kg/m³ ) making it adaptable for numerous applications in the construction, industrial, chemical, horticultural and petrochemical industries. A unique use for perlite is in cementing, oil, gas, water and geothermal wells.

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.

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.

TYPICAL PERLITE WELL CEMENT AGGREGATE SCREEN SIZE
U.S. Mesh	I.S.O. (mm)	% Passing
8	2.4	100.0
16	1.2	75.0
30	0.6	40.0
50	0.3	14.0
100	0.15	4.0
200	.075	1.1

TYPICAL CHEMICAL ANALYSES^*
Silicon	33.8
Aluminum	7.2
Potassium	3.5
Sodium	3.4
Iron	0.6
Calcium	0.6
Magnesium	0.2
Traces	0.2
Oxygen (by difference)	47.5
.....Net Total	97.0
Bound Water	3.0
* All analyses are shown in elemental form even though the actual forms present are mixed glassy silicates. Free silica may be present in small amounts, characteristic of the particular ore body. More specific information can be obtained from the ore supplier involved.

If you think your application would benefit from the properties of perlite please let us know by calling or contacting us at:

WELL CEMENTS	SCHUNDLER
WELL CEMENTING	PRODUCT GUIDE
	The Schundler Company 10 Central Street Nahant, MA 01908 732-287-2244 www.schundler.com