Geological controls on gas flow pathways in coal seams

Kinnon, Emma and Esterle, Joan (2008). Geological controls on gas flow pathways in coal seams. In: International Coalbed and Shale Gas Symposium 2008, Tuscaloosa, Alabama, (). 19-23 May 2008.


Author Kinnon, Emma
Esterle, Joan
Title of paper Geological controls on gas flow pathways in coal seams
Conference name International Coalbed and Shale Gas Symposium 2008
Conference location Tuscaloosa, Alabama
Conference dates 19-23 May 2008
Convener University of Alabama
Place of Publication New York, N.Y., U.S.A.
Publisher Curran Associates
Publication Year 2008
Sub-type Fully published paper
ISBN 9781605603216
Language eng
Abstract/Summary Coal bed methane (CBM) has recently become an important source of energy for Queensland, with operations currently underway in the Bowen and Surat basins, together producing around 27PJ of the state’s energy annually (Draper, 2006). The benefits of this resource are that it utilizes the coal which occurs abundantly in this region and produces less greenhouse gas emissions than conventional coal-fed power stations. Further greenhouse reductions might be achieved through geosequestration of CO2. Geosequestration into unmineable and gas depleted coalfields is a topic of research. However, coal is a heterogeneous reservoir in which gas flow for production, much more for CO2 injection, is poorly understood. This analogue project uses production data obtained from an undisclosed field to determine how the geology of the field affects production rates. This information can then be applied to determine which areas of the field would be the best locations for future gas production wells. A model of the production rate over the lifespan of the gas field will be created which will also increase our knowledge of how gas flows through coal. This information can then be used as an analogue for gas flow in basins elsewhere considering enhanced gas recovery. Gas production data has been interpolated and contoured across the field to illustrate the gas production rates over time for a two year period for two target seams. Both seams exhibit similar production patterns which indicate that the prevailing influence on the variation in production rates between wells is due to the structural geology of the region rather than variations in the individual coal seams. The area of greatest production shows that production rates have been continually high since they have been online and occur on the flank of an anticline. A large normal fault marks the boundary between good producing wells and poorer producing wells and it coincides with a master split in the upper and lower plies of the coal seam across the crest of the anticline. A number of smaller faults also occur in this poorly producing area. The palaeo-channel that created the split elevates the mineral matter content of the target seam prior to splitting which could reduce its permeability. These results, combined with initial virgin gas and saturation levels, suggest that internal baffling of gas flow occurs during production are due to both structural and architectural features of the seam. Further analysis of the data needs to be conducted to quantify the impact each of these features have on the production and why.
Subjects 240000 Physical Sciences
260000 Earth Sciences
EX
Q-Index Code EX
Q-Index Status Provisional Code

 
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Created: Wed, 06 Aug 2008, 11:00:05 EST by Laura McTaggart on behalf of School of Mathematics & Physics