What Is Sulphonated Asphalt?

Sulphonated asphalt is a modified asphalt product used as a shale stabilizer and fluid loss additive in water-based drilling fluids. It is usually supplied as a black, free-flowing powder in 25 kg (50 lb) bags.

How it is made

Asphalt is reacted with a sulphonating agent and then neutralized, often with sodium hydroxide. This introduces sulphonate groups that make part of the product water-soluble while the rest remains as fine asphalt particles.

What it does

• Stabilizes shale by coating and sealing shale surfaces
• Reduces HPHT fluid loss and improves filter cake quality
• Reduces torque and drag through boundary lubrication
• Reduces bit balling in reactive clays
• Can partially substitute for oil in some lubricated systems

Typical properties

• Appearance: black powder
• Water solubility: partial (commonly 50–75%)
• pH (1% solution): around 8–10
• Moisture: low

Dosage

Typical treatment is 2–6 lb/bbl, added through the mixing hopper.

Compatibility

Compatible with most water-based mud systems, including KCl-polymer and lignosulfonate muds. Can cause foaming in some systems; a defoamer may be needed.

How it differs from gilsonite

Packing and handling

Sun Gilsonite supplies sulphonated asphalt in printed 25 kg (50 lb) multi-wall kraft bags marked with health and safety information, batch number and dates. Store dry and keep bags sealed to avoid caking.

Sun Gilsonite supplies sulphonated asphalt in printed 25 kg kraft bags with batch and safety information. See also sulphonated asphalt dosage guide.