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Rock Properties

Advanced Rock Properties - RwCore™

RwCore™ is a quick, nondestructive, accurate method for determining formation water resistivity (Rw).

Uncomplicate the core Rw measurement. Much uncertainty can exist in reserves determination in the Rw variable alone, particularly in reservoirs that don't produce water. Core-based Rw methods have included direct measurement on water produced by centrifugation or ionic speciation after distillation and leaching and subsequent conversion to resistivity.

RwCore™ is a new and improved resistivity-based method that provides rapid Rw determinations on fresh or preserved core samples.

RwCore Accuracy

The RwCore™ model was developed experimentally and was laboratory-tested extensively prior to implementation. The data on the right illustrate one such experimental sequence. A suite of core samples was saturated with carefully prepared brines of known resistivity and were tested on a blind basis.

These data illustrate the accuracy and the measurement range of the RwCore™ protocol.

  • Accurate - < 1% deviation
  • Measurement Range - from 0.035 to 50.0 Ω-m (100 to 230,000 ppm NaCl)

RwCore Core-Base Comparison

This data comparison illustrates RwCore™ compared to traditional "ionic speciation" which is rather time-consuming and requires sample destruction. The experimental variation, although acceptable, is predominantly attributed to ionic speciation. RwCore™ is ideally suited for shale reservoirs:

  • Requires ionic permeability
  • Unaffected by clay bound water
  • Independent of water saturation and the presence of liquid hydrocarbons

RwCore™ provides formation water resistivity from core, cuttings, and liquids using resistivity-based measurements.

RwCore Water Resitivity


  • Rapid - provides results in a day
  • Direct core measurement
  • No fluid displacement or chemical analysis
  • Nondestructive - sample maintained
  • Unaffected by sample lithology
  • Ideal for shale reservoirs
  • Unaffected by clay bound water
  • Independent of saturation and fluids present

Sample Requirements

  • Wide range of samples - plugs, cuttings, and liquids
  • Any diameter right cylinder; ¼ - inch minimum length

Example Data Set

RwCore Data Set

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