Shale stabilizer and inhibitor system

Schlumberger Oilfield Services

KLA-GARD shale stabilizer and inhibitor system reduces the swelling of sensitive shales and drill cuttings exposed to water-based drilling fluids. It inhibits shale hydration, reduces the effect of drill solids on viscosity, and works to minimize problems such as

  • excessive dilution rates
  • increased torque and drag
  • high surge and swab pressures
  • bottomhole assembly balling.

This high-quality, concentrated product has applications in a wide variety of mud systems and has low-toxicity characteristics as to be considerable for offshore applications.

Typical Physical Properties
Physical appearance Clear blue liquid
Specific gravity 1.1
pH (1% solution) 6.5–8.5
Solubility in water at 20 degC [68 degF] 100%
Flash point >99 degC [210 degF] (Pensky–Martens closed cup)


  • For systems where additional inhibition is needed as an alternative to gyp, lime, and potassium systems.
  • Only be added to mud systems containing low concentrations of active solids, bentonite-free systems, or freshly prepared low-solids systems containing a minimum amount of prehydrated bentonite. These systems should have a methylene blue test (MBT) capacity of less than 35.6 kg/m3 [12.5 lbm/bbl] with 5.7 to 14.3 kg/m3 [2 to 5 lbm/bbl] of prehydrated bentonite for filtration control.
  • Compatible with most drilling fluid additives and is especially suited for use in freshly prepared, low-solids polymer systems such as the POLY-PLUS system. It is most effective when the use of organic thinners, such as SPERSENE lignosulfonate, is minimized.

Normal concentrations of KLA-GARD system range from 11.4 to 22.8 kg/m3 [4 to 8 lbm/bbl] depending on hole size, rate of penetration, interval length, and reactivity of the shale. A minimum concentration of 11.4 kg/m3 [4 lbm/bbl] is required for the product to be effective. One lbm/bbl of KLA-GARD system contributes 508-mg/L chlorides; KLA-GARD B stabilizer, a chloride-free formulation, is available. To prevent bacterial attack, a biocide should be used.

KLA-GARD system works by being adsorbed onto active solids, thereby reducing their sensitivity to water. This action causes the product to be depleted from the mud system at a rate dependent on the reactivity of the formation, cuttings size, and amount of hole volume drilled. A test procedure is available to monitor the approximate concentration of excess KLA-GARD system.

Estimated Depletion Rates
Hole size, in 6 1/8 8 1/2 9 7/8 12 1/4 14 3/4 17 1/2
KLA-GARD system, lbm/100 ft [kg/30 m]
107 [48]
205 [92]
277 [124]
426 [190]
617 [276]
869 [388]

Estimated depletion rate is based on a highly reactive shale. This table is based on 5.2-lbm KLA-GARD system per cubic foot of gumbo shale drilled. Actual depletion rates can vary, depending on the reactivity of the shale and the cuttings size.


  • Highly effective shale stabilizer
  • Effective at all pH levels
  • Environmentally acceptable
  • Stable at temperatures in excess of 204 degC [400 degF]
  • Reduced potential for bit balling
  • Reduced the amount of dilution required and the associated treatment costs
  • Unaffected by contaminants such as hard water, cement, or CO2


  • Should not be added to systems containing high concentrations of active solids; flocculates muds with high MBT values, causing excessive viscosity
  • Limits the hydration of all clay materials; therefore, bentonite additions must be prehydrated in freshwater
  • Due to the interaction of KLA-GARD system with active solids and bentonite, give increased attention to filtration control
  • Biodegradable; requires a biocide

Toxicity and handling

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

Packaging and storage

KLA-GARD system is packaged in 208-L [55-galUS] drums and 18.9-L [5-galUS] cans. Store in a dry, well-ventilated area. Keep container closed. Keep away from heat, sparks, and flames. Store away from incompatibles. Follow safe warehousing practices regarding palletizing, banding, shrink-wrapping, and stacking.