Sulfex® – Shale inhibitor – Sulphonated Bitum (Asphalt)

Sulphonated asphalt (Sulfex), Shale inhibitor

SULFEX® (Shale inhibitor) is a universal reagent for drilling fluid which stabilizes the shale formations, significantly improves the lubricating properties of drilling fluid and reduces filtration in high pressure and temperature conditions, as well as improves the filter cake properties in water- and oil-based drilling fluids. The product can be added to most aqueous and hydrocarbon solutions as well as synthetic solutions.

The unique composition of the SULFEX® (Shale inhibitor) additive has demonstrated outstanding results in all types of drilling fluids providing the following benefits:

• Reacts with shale clay to prevent shale slumping and swelling
• Reduces filtration at high pressure and high temperature, see Figure
• Creates a thin compressible filtration layer
• Significantly increases the lubrication properties either on addition in pure form or in combination with a small amount of petroleum and synthetic materials
• Prevents drilling tools from sticking
• Extremely heat-resistant material – has no softening point which is usually associated with non-reacting bituminous additives
• Minimal and easily recognizable fluorescence – does not interfere with well logging or core analysis
• Does not leave oil stains, films or rainbow streaks on water in marine areas
• Does not require emulsifiers for proper mixing performance
• Does not require phasing out of equipment for solids removal during mixing
• Reduces thickening at high temperatures and stabilizes the properties of drilling fluid


The SULFEX® (Shale inhibitor) additive is produced by sulfonation of bitumen. The sulfonation process allows to achieve a highly anionic product generally dissolving in water by over 50 %. Bitumen is neither anionic nor water-soluble. Therefore, after sulfonation Sulfex® additive no longer has the chemical or physical properties of bitumen. In terms of the chemical properties, it also differs from gilsonite and oxidized bitumen which are not subjected to sulfonation but are sometimes erroneously characterized as “substitutes of Sulfex® sulfonated asphalt additive”.

SULFEX® additive technology also provides an advantage over gilsonite and bitumen in terms of particle size. As a sulfonated/reactive material, the SULFEX® reagent features a wide range of particle sizes from soluble to colloidal, including sizes comparable to that of ground materials. The wide range of sizes provides a high probability of obtaining a particle size required for penetration into various types of cracks. Virtually all particles of the SULFEX® additive, regardless of the size, feature high anionic activity. When the fractional composition of the particles is combined with the highly charged particles, thereby revealing the shattered edges of shale clay, it becomes apparent that the SULFEX® additive provides a significant advantage over the inert materials sometimes referred to as “substitutes of the SULFEX® additive.”

If there is an issue of possible damage to reservoirs, the SULFEX® additive has an added advantage. It partially dissolves in oil and partly in water. The extracted liquids will gradually dissolve the SULFEX® additive in the seams. Gilsonites and bitumens are completely insoluble in water and only partially soluble in hydrocarbons and, therefore, have a lesser likelihood of elution by the flow of the produced liquid.

The SULFEX® clay stabilization additive (Shale inhibitor), its ability to reduce high pressure and high temperature filtration, and reduce the torque and tightenings in the wellbore are also good reasons for using SULFEX® in all drilling fluids, both in water and on a hydrocarbon base.




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