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Fluid Sensitivity Screening by Capillary Suction Time (CST) and Roller Oven (RO) Analysis


  • The Capillary Suction Time TestTubing measures the relative flow capacity of a slurry of ground formation rock used to form an artificial core and it is an indication of clay swelling.
  • A rock sample with dispersible or swelling clays would have a lower pseudo permeability and will have a longer CST time while the one without clay or other fine particles would have a shorter retention time.

  • The Roller-Oven Shale Stability Test simulates the circulation of the completion fluid around ground rock particles
  • Studies the reduction of particle size due to mechanical attrition and reaction of shale particles with various test fluids
  • Measures erosion of shale in the presence of various salinity fluids (KCl, NaCl, fresh water), Clay controls, Completion fluids, Additive packages, etc.


The CST and RO analyses are used as preliminary screening tools to study the relative sensitivity of a rock sample to various fluids:

  • Guidance for drilling & completion fluids
  • Analysis of various Production Water/Fresh Water Ratios
  • Clay Control comparisons
  • Depletion Studies