Gas Content Testing

GeoGAS offers both Fast and Slow desorption.

The Fast and Slow desorption methods both involve the determination of Q1 (lost gas), Q2 (desorbed gas) and Q3 (residual gas, i.e. gas released on crushing). The sum of these three components is the “Measured Gas Content,” also known as “Qm” as defined in AS 3980-1999.


Q1 (lost gas) cannot be measured but is estimated based on field gas desorption measurements,
i.e. on-site gas measurements are taken in the field as soon as the core sample has been drilled and placed inside of a canister.

The term ‘Q1 readings’ is commonly used to distinguish between gas desorption measurements taken in the field and those taken in the laboratory. Though technically speaking, Q1 readings form part of the Q2 measurements.

  • Most customers prefer to use their own on-site staff for Q1 readings - GeoGAS offers its support through Q1 Training before the drilling campaign begins to ensure the on-site crew understands how to take accurate Q1 readings and prepare a sample for transport.
  • GeoGAS can also make available its own staff for on-site Q1 testing. Pricing for this service is available on request.


Q2 readings are taken in our laboratory. GeoGAS customers can choose between the Fast or Slow desorption method and we can advise you on which method best suits your testing needs.


Q3 readings are taken in our laboratory.  During this process, two 150g representative sub-samples are taken from the core and crushed for Q3 determination. GeoGAS uses high quality Rocklab Ring Mills that have been specially modified for our gas testing needs.


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