Gilsonite is used as a fluid loss control additive, or FLC, in oil based mud. Its high softening point — 160 °C and above — delivers over 50% fluid loss reduction compared with other additives, and it survives conditions where most mud additives do not. In synthetic based muds it can cut cost by up to 80% against UHT co-polymers, which is why mud manufacturers in China, India, the GCC and Latin America have moved to it.
Gilsonite as a fluid loss control additive in oil based mud
Gilsonite works in oil based mud because of its hydrocarbon nature and its softening point. Both matter, and they work together to cause a significant decrease in fluid loss during drilling.
Gilsonite solubility in oil — measured by dissolution in trichloroethylene, carbon tetrachloride and carbon disulphide — allows the additive to interact properly with the oil phase of the drilling mud, in most cases diesel. The same characteristics make gilsonite powder effective in synthetic based muds, where the base material is a polymer rather than an oil distillate.
The three mud systems
| System | Base material | How gilsonite functions |
|---|---|---|
| OBM — oil based mud | Oil product, typically diesel | Dissolves into the oil phase, builds filter cake, controls fluid loss |
| WBM — water based mud | Water | Acts as a bridging and plugging solid rather than dissolving |
| SBM — synthetic based mud | Polymers | Same mechanism as OBM. Replaces UHT co-polymers at a fraction of the cost |
Gilsonite is used across all three systems, but in different aspects and manners. In drilling rigs, mud is applied to reduce the temperature of the hole while providing efficient drilling, and acts as a lubricant through the process. In the stricter environmental conditions where synthetic muds are required, applying gilsonite may decrease costs by 80% compared with the substitute material, UHT co-polymers.
Iranian gilsonite grades for fluid loss control
Iranian gilsonite exists in many different qualities and types, but only two grades are suitable for FLC application, and both are supplied by RAHA Gilsonite Co.
These products have been tested and proven over years of service in China, India, the GCC countries and in South America including Mexico. They are now replacing the American gilsonite grades — XM-P, LM-P, GM-P and even the HT series — across those markets.
American gilsonite is itself very cost-effective compared with synthetic alternatives. Iranian gilsonite performs at a comparable level at a more economical price, which gives mud manufacturers real leverage on production cost in the current oil market. RAHA Gilsonite supplies various grades worldwide with quality guaranteed for each shipment.
Advantages of gilsonite as fluid loss controller in OBM and SBM
-
Over 50% fluid loss reduction
The high softening point of 160 °C and above delivers greater reduction than competing additives, and holds that performance at elevated bottomhole temperature.
-
HSE compliant
Non-toxic, so it adapts to the HSE limitations applied to oil based and synthetic based mud systems without special handling.
-
Improved filter cake
Elevates filter cake expansion, producing a thinner, more competent cake against the formation face.
-
Shale stabilisation
Acts as a shale stabiliser alongside its filtration function, addressing two problems with one addition.
-
Cost effective
Substantially cheaper than synthetic FLC additives, and up to 80% cheaper than UHT co-polymers in synthetic systems.
-
Extreme condition performance
Performs in drilling environments where few mud additives survive — and does so at lower cost than those that do.
Case history: eliminating logging tool sticking in oil based mud
An international oil company successfully drilled multiple HP/HT wells offshore in Asia but experienced delays and problems during logging operations due to the tendency of logging tools to stick.
| Well parameter | Range |
|---|---|
| Well depth | 14,010 ft to 15,960 ft |
| Bottomhole temperature | 400 °F to 432 °F |
| Mud density | 10.4 ppg to 14.4 ppg |
| Mud system | Oil based mud |
| Problem | Logging tools sticking, non-productive time |
The oil company and the drilling fluids provider conducted laboratory testing which confirmed that adding a high softening point gilsonite to the oil based mud would improve filtration characteristics and filter-cake development. This treatment strategy was adopted during the final drilling phase, before logging commenced.
The result. Gilsonite proved effective in optimising drilling fluid performance characteristics, eliminating the logging tool sticking tendency and allowing wireline logging to run for over 90 hours. The operator reduced costs by eliminating non-productive time during the logging process.
When conditions are the worst, gilsonite is the best
Gilsonite is a safe, naturally occurring hydrocarbon resin with a high softening point. It performs in the most extreme drilling environments, where few mud additives can survive — and at a lower cost than the synthetics that can.
Naturally occurring gilsonite provides extreme performance with no HSE risk
Gilsonite has significant health advantages over synthetic products. It is non-toxic, non-carcinogenic and non-mutagenic, and requires only standard PPE safety measures for handling or disposal. In jurisdictions where synthetic additive disposal is regulated or restricted, that difference is not marginal.
| Gilsonite | Synthetic FLC additives | |
|---|---|---|
| Origin | Naturally occurring hydrocarbon resin | Manufactured polymer |
| Toxicity | Non-toxic, non-carcinogenic, non-mutagenic | Varies by product; often regulated |
| Handling | Standard PPE | May require additional controls |
| Disposal | Standard measures | May be restricted in sensitive areas |
| Cost in SBM | Baseline | Up to 5× higher for UHT co-polymers |
| HP/HT performance | Proven to 432 °F in field use | Product dependent |
Frequently asked questions
How does gilsonite control fluid loss in oil based mud?
Through its hydrocarbon nature and high softening point working together. Gilsonite is soluble in the oil phase of the mud — typically diesel — which allows it to interact properly with the base fluid, deposit at the formation face and build a thinner, more competent filter cake. The result is over 50% fluid loss reduction compared with other additives.
What softening point is needed for OBM applications?
160 °C and above. The softening point is what allows the additive to hold its function at elevated bottomhole temperature rather than deforming and losing the filter cake. Field use has proven high softening point gilsonite at bottomhole temperatures up to 432 °F.
Can gilsonite be used in synthetic based mud?
Yes, and it is one of the strongest commercial cases for it. The same characteristics that make gilsonite work in oil based mud apply in synthetic systems, where the base material is a polymer. In stricter environmental drilling where synthetic muds are required, applying gilsonite may decrease costs by 80% compared with the substitute material, UHT co-polymers.
What is the difference between using gilsonite in OBM and WBM?
The mechanism. In oil based and synthetic muds, gilsonite interacts with the base fluid and functions primarily through filter cake development. In water based mud it does not dissolve, so it acts as a bridging and plugging solid instead. Gilsonite is used across all three systems but in different aspects and manners.
Which Iranian gilsonite grades are suitable for FLC?
Only two grades of Iranian gilsonite are suitable for fluid loss control application, and both are supplied by RAHA Gilsonite Co. These have been tested and proven over years of service in China, India, the GCC countries and South America including Mexico.
How does Iranian gilsonite compare with American grades?
Iranian gilsonite performs at a comparable level to the American grades — XM-P, LM-P, GM-P and the HT series — at a more economical price. American gilsonite is itself cost-effective against synthetic alternatives; Iranian material extends that advantage further, which is why it is replacing US grades across several markets.
Is gilsonite safe to handle on a rig?
Yes. Gilsonite is non-toxic, non-carcinogenic and non-mutagenic, and requires only standard PPE safety measures for handling or disposal. That gives it significant health advantages over synthetic products and makes it suitable where HSE limitations apply to the mud system.
Does gilsonite do anything besides fluid loss control?
Yes. It acts as a shale stabiliser alongside its filtration function, and it elevates filter cake expansion. That means one addition addresses fluid loss, wellbore stability and cake quality rather than requiring separate products for each.
What concentration is used in oil based mud?
Concentration depends on the mud weight, bottomhole temperature and the fluid loss target, and is normally established by laboratory testing with the specific mud system. Send us the mud formulation and the conditions and we will advise on the grade and starting concentration.
What forms do you supply for drilling applications?
Granular and micronized powder, with mesh sizes of 30–40, 100, 200, 300 and custom cuts. Ash content, softening point and particle size distribution are adjusted to the application. Low-ash grades under 5% ash are available where ash content governs.
Related pages
Drilling applications: gilsonite in drilling fluids, water based muds, gilsonite in cementing, oil and gas overview and bentonite.
Product information: gilsonite overview, specification, properties, micronized powder, price, MSDS and HS code.
Specify gilsonite for your mud system
Send us the mud system, the bottomhole temperature, the mud weight and the fluid loss target. We will confirm which of our FLC grades fits, supply a batch certificate of analysis before loading, and accept third-party inspection by SGS, Bureau Veritas or the surveyor named in your contract.
Dubai: No. 2305, Burlington Tower, Business Bay — +971 4 566 4998
Ankara: Karşıyaka District, 749 Street No. 30, Gölbaşı 06830 — +90 312 544 5481
