Gilsonite is a natural asphaltite used for high-temperature filtration control and wellbore stability, mainly in oil-based mud. Ironstone supplies drilling-grade gilsonite / asphaltite powder with a certificate of analysis for every batch — and states what material is in the sack.
Downhole heat softens the gilsonite particles, and the softened material presses into the filter cake and into small openings in the wellbore wall. The result is a tighter filter cake at high temperature — seen in HPHT filtrate numbers — and a wellbore surface less exposed to fluid invasion. Because the softening behavior is the working mechanism, the softening-point range is matched to the well: material that softens far below the bottom-hole temperature smears, and material that softens far above it acts largely as inert filler.
Material sold as “gilsonite” on the world market ranges from true mined natural asphaltite to factory-modified or oxidized asphalt made to imitate it. Any of these can be the right commercial choice — the failure mode is paying for one and receiving another. The checks on the certificate of analysis are ash content and softening point: high-purity natural asphaltite runs low ash, while a very low softening point suggests a modified or oxidized material. We state the material and its origin on the quotation. Our VERSATROL / BARABLOK equivalents page covers the sourcing distinction in full.
| Parameter | Typical value | Basis |
|---|---|---|
| Softening point | 160 – 220 °C (drilling grade) | ASTM D36 |
| Ash content | About 3 – 20% (by grade) | ASTM D3174 |
| Moisture | 1 – 7% | ASTM D3173 |
| Volatile matter | About 63 – 90% | ASTM D3175 |
| Penetration at 25 °C | ≈ 0 (hard, non-penetrating) | ASTM D5 |
| Specific gravity | 1.01 – 1.12 | ASTM D3289 |
| Mesh | 200 (WBM) · 100 (OBM) · 325 (HPHT) | Sieve |
Typical drilling-grade values; general gilsonite specifications span wider ranges, so the certificate of analysis states the exact figures and the origin for each batch.
Because material types differ in cost, we price only after the grade, mesh, and origin are agreed. Indicative FOB ranges appear in the monthly Price Letter. For a firm price, send your system, mesh, and volume on WhatsApp.