Project summary: 

The amount of coal seam gas that can be produced from a coal bed is dependent on the thickness of the coal, gas content, permeability and the depth of the coal seam. Determining permeability of coal seams is an important part of estimating gas production from a well in reservoir models. Currently permeability is estimated from well test analysis. However, permeability estimates based on well test analyses have become more challenging as coal permeability is spatially highly variable between adjacent wells. Variability in permeability is also present at different scales and is determined by coal seam distribution and continuity, composition, diagenesis, geomechanical characteristics and reservoir stress evolution. Over a short range (at the near well to inter-well scale) an even higher variability in permeability exists due to the connectivity of fracture networks between adjacent wells, and this makes predicting associated porosity and permeability difficult. It is for instance not unusual to find a variation in production of 50-70% between neighbouring wells within short distances (few kilometres) of each other. One of the key challenges is modelling short-range continuity of different categories of absolute permeability.

This project sought to understand and better characterise the short-range variation in permeability between wells. 

This project aims were to: 

  1.  Examine measurements of different (proxy) properties at the short range scale to provide information on continuity, variability and randomness of coal permeability.
  2. Develop single well and interference test models based on the new characterisation of short range permeability.
  3. Use different approaches in modelling (correlation schemes, geostatistical inference, etc.) to improve current modelling practice
  4. Calibrate and validate test models using field data.   
Project status: 
Project leader or contact: 
Team members: 
Start date: 
May 2015
Completion date: 
April 2017
Output availability: 
Notes: 

Outputs:

  1. A set of guidelines in the determination of optimal reservoir scale properties for coal seam gas reservoirs of varying permeability heterogeneities. These guidelines and workflows will be calibrated and verified with well pressure test data and interference test data.
  2. Guidelines on the selection of appropriate estimation algorithms over inter-well scales and recommendations on appropriate modelling strategies.
  3. Guidelines on the selection of upscaling algorithms and their suitability to use models constructed at the inter-well scale.
  4. Identification of new algorithms and software tools and, if applicable, a scope variation to develop these tools.
Project output: 
Record number: 
475
This information has been collated by the Centre for Coal Seam Gas. The project summary on this page may be a reproduction or adaptation of the researcher’s own published description of the project, which is generally available via the link to online information located beneath the summary. In other cases, the summary has been provided directly by the researcher or their organisation.