Petroleum Geochemistry Division – Unconventional Gas
Coal Seam Gas, Shale Gas & Tight Gas Sands...

Gas production from coal beds, shales and tight sands is a developing energy resource in Australia. Internationally, the USA, Europe, China, and Canada have programs aimed at unconventional gas recovery.

Coal Seam Gas (CSG), also known as Coal Seam Methane (CSM) and Coal Bed Methane (CBM), has seen dramatic growth over previous years and now accounts for over 13% of Australia’s domestic gas supply.

Gas bearing shales and tight sands are also making an emergence due to the application of newer technologies such as horizontal drilling and advanced stimulation methods, improving the economics of these resource plays.

GAS CONTENT OF CSM AND SHALE GAS RESERVOIRS
Accurate gas content measurements are essential in assessing CSG and shale gas reservoirs. Well recognized and documented techniques are utilized to determine gas content, including desorption and residual gas experiments conducted at reservoir temperature.

Total Gas Content = Lost Gas + Desorbed Gas + Residual Gas

   Lost Gas – gas that is lost while tripping out of the hole, extrapolated from         desorption data collected at the wellsite
   Desorbed Gas – gas released from a desorption canister over time, initially         measured in the field and completed in the lab
   Residual Gas – gas that remains sorbed on the coal after completion of the         desorption test, lastly determined in the laboratory

Adsorption Isotherm analysis is also used to assess reservoir saturation

CHARACTERISATION METHODS
A range of other assessments are utilized for Coal Seam Gas, Shale Gas and Tight Gas Sands to assess the economics of developing the reservoir. Depending upon the resource type, these may include:

Gas Composition	CT Scanning
Gas Isotopes	XRD
Proximate Analysis	Thin Section Petrography
Maceral Description	Rock Mechanics
Vitrinite Reflectance	Hg Injection Capillary Pressure
Density	Rock Eval / TOC
Porosity	Whole Extract GC-MS
Permeability	Oil/Gas/Source Rock Correlation
Ultra-low Pulse Decay Permeability	Water / Brine Analyses