Gilsonite natural asphalt (asphaltite) additive is an mineral bitumen hydrocarbon in granular form. Its particle size varies between 4- and 200-mesh. Pulverized Gilsonite is commonly used to control lost circulation.
It is effective at bottom hole temperatures (BHTs) between 60Â° and 230Â°F (16Â° and 110Â°C). Typical additive concentrations range from 5- to 50-lb/sk of cement mud.
The low specific gravity of Gilsonite powder helps improve its ability to control lost circulation. However, this feature can also cause the additive to separate to the top of thin slurries and slurries containing dispersants. Adding 2% or more bentonite to the slurry will help prevent separation.
Gilsonite additive can provide the following benefits:
When perforated, it is shatter-resistant.
It does not significantly affect the setting time of cement.
Gilsonite additive can provide higher strength than heavier additives with high water requirements.