DUO‑VIS (often written DUOVIS) and BARAZAN D are brand names for drilling-grade xanthan gum — the biopolymer the industry also calls XC polymer. Xanthan is a fermentation product made by specialist factories worldwide; the drilling grades are specified by viscometer performance, not by brand. Ironstone supplies drilling-grade xanthan in standard and dispersible grades, with a certificate of analysis for every batch.
Both are xanthan gum: a high-molecular-weight polysaccharide produced by fermentation. What makes xanthan valuable in drilling fluid is the shape of its viscosity curve. It is strongly shear-thinning — thin where the fluid moves fast (inside the drill string and at the bit, keeping pump pressure manageable) and thick where the fluid moves slowly (in the annulus, where cuttings must be carried, and when circulation stops, where barite and cuttings must be held in suspension). That low-shear-rate viscosity is the property the brand products are sold on, and it is the property a compatible xanthan must reproduce.
The base polymer is the same — the grades differ in qualification and treatment, not in the molecule. Food grade is certified for purity and food-safety compliance. Drilling grade is specified for performance in mud systems — viscometer readings at defined dosages, behavior in salt water, and particle treatment for field mixing — and it is tested against oilfield test methods rather than food standards. Buying on the name “xanthan” alone, without the drilling-grade specification, is how mismatched material ends up on a rig.
Untreated xanthan powder hydrates fast at the particle surface, so it can clump into fish-eyes if it is dumped into water faster than it can disperse. Dispersible grades (the “D” in several brand names) are treated so the particles separate and wet before they hydrate. The choice is about your mixing equipment, not about downhole performance:
| Grade | Choose it when |
|---|---|
| Standard | You mix through a proper hopper or high-shear mixer with controlled, slow addition — the lower-cost option. |
| Dispersible | Mixing is manual, fast, or done in the field with basic equipment — HDD tanks, small rigs, remote sites — and fish-eyes are the known failure mode. |
| Parameter | Why it decides the match |
|---|---|
| Low-shear viscometer readings at stated dosage | The 6 and 3 r/min dial readings and gel strengths are the readings xanthan is bought for — suspension is the job. |
| Full rheology profile at stated dosage | Confirms the shear-thinning curve, so hydraulics and dosing tables carry over unchanged. |
| Performance in salt water | Field mix water is rarely fresh. Compare readings in the brine that matches your operation. |
| Dispersion behavior | A dispersible grade must actually disperse through your equipment — test it with your mixing method. |
| Moisture and purity | Decides true active content per sack and storage life. |
Xanthan gum test methods are covered by API Specification 13A. We report COA results against the 13A test procedures and state the edition on the document.
Test on the bench first: same dosage, same mix water, same viscometer sequence as your current product, plus a realistic mixing test — xanthan failures in the field are usually mixing failures, not chemistry failures. If the bench holds, run one section with the candidate while keeping your current stock as backup, and watch the low-shear readings and sag behavior over a full circulation cycle before committing the program.