IDCAP D Polymeric Shale Inhibitor | Schlumberger


Polymeric shale inhibitor

IDCAP D shale inhibitor provides excellent cuttings encapsulation by adsorbing onto the clay surfaces and forming a protective film that prevents cuttings from sticking to each other or to the shaker screens. IDCAP D shale inhibitor limits dilution rates and low-gravity-solids loading by preventing clay solids from dispersing into the mud system. This product is effective in a wide range of base brines, including seawater, saturated sodium salt, and potassium chloride but should not be used in calcium brines. Typical concentrations of IDCAP D shale inhibitor range between 0.5 and 4 lbm/bbl [1 and 12 kg/m3].

Due to the low molecular weight of this polymer, the mixing process requires less shear than polymers with higher molecular weights. The resulting fluid will pass through fine shaker screens without blinding.

IDCAP D shale inhibitor concentration should be calculated by mass balance assuming an approximate depletion rate and observing the quality of the cuttings at the shakers. Cuttings that appear dry inside but ball or stick to shakers may indicate low shale inhibitor levels. Conventional ammonia extraction testing cannot be used to determine residual concentration because IDCAP D inhibitor does not produce ammonia when exposed to elevated pH.

Dilution rates with premix should be based on the depletion rate of the IDCAP D shale inhibitor. Premix concentrations can range as high as 5 lbm/bbl [12 kg/m3], depending on the depletion rates.

Calcium hardness in makeup water should be treated out with soda ash before use. Maintain pH below 10 for optimal performance, where applicable. IDCAP D shale inhibitor does not contain acrylamide, so hydrolysis with NH3 release is not a problem.

Typical Physical Properties  
Physical appearance White powder
Specific gravity 1.4–1.6
pH (1% solution) 6.0
Solubility in water Soluble


  • Freshwater, seawater, and saturated NaCl and KCl applications


  • Provides excellent cuttings encapsulation, limits cuttings dispersion, and improves shale stabilization
  • Enhances removal of drill solids by reducing dispersion tendencies
  • Contributes minimally to the viscosity of the system
  • Adds easily to the active system through a premix
  • Significantly lower screen blinding potential compared with higher-molecular-weight inhibitors
  • Can be used in high-pH fluids (silicates) for enhanced control of highly dispersive (kaolinite or illite) shales


  • Fluid systems containing IDCAP D shale inhibitor should be pretreated with either citric acid or sodium bicarbonate before drilling cement to avoid chemical precipitation by calcium ions
  • Should not be used in systems with calcium content above 500 mg/L
  • Magnesium concentration above 2,700 mg/L might diminish its performance
  • Check for compatibility and run performance testing when using IDCAP D inhibitor in high-performance water-based mud with amine inhibitor concentrations higher than the maximum recommended 3 vol %.

Toxicity and handling

Bioassay information is available upon request. Handle as an industrial chemical, wearing protective equipment and observing the precautions as described in the safety data sheet.

Packaging and storage

IDCAP D shale inhibitor is packaged in 25-kg [55.1-lbm] multiwall paper sacks. Keep away from open flames, hot surfaces, and sources of ignition. Keep containers tightly closed in a dry, cool, and well-ventilated place.

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