Sulphonated Asphalt Dosage Guide for Water-Based Mud

Getting the dosage right ensures you get the benefits of sulphonated asphalt without wasting product.

Typical treatment levels

How to add

1. Add slowly through the mixing hopper.
2. Mix with good shear.
3. Allow time for full dispersion before testing.
4. Monitor foaming; add defoamer if needed.

What to measure

• API and HPHT fluid loss
• Rheology
• Shale dispersion or swelling tests
• Torque and drag trends at the rig

Maintaining concentration

Sulphonated asphalt is consumed as it coats shale and cuttings. Make regular additions while drilling shale to keep concentration steady.

Common mistakes

• Adding too quickly, causing lumps
• Under-treating in highly reactive sections
• Ignoring foaming

Example: treating a reactive shale section

A water-based KCl-polymer mud is about to drill a reactive shale. The engineer pre-treats the active system with 3 lb/bbl of sulphonated asphalt, then raises the concentration to 5 lb/bbl as cavings appear, while monitoring HPHT fluid loss and rheology.

Calculating sacks needed

Sacks = (active volume in bbl × dosage in lb/bbl) ÷ 50 lb per sack.

For 1,000 bbl at 4 lb/bbl: 1,000 × 4 ÷ 50 = 80 sacks.

Order sulphonated asphalt in 25 kg bags or jumbo bags. Compare with gilsonite in sulphonated asphalt vs. gilsonite.