Bulletin Article

Gas saturation and CO2 enhancement potential of coalbed methane reservoirs as a function of depth  

The influence of moisture, temperature, coal rank, and differential enthalpy on the methane (CH4) and carbon dioxide (CO2) sorption capacity of coals of different rank has been investigated by using high-pressure sorption isotherms at 303, 318, and 333 K (CH4) and 318, 333, and 348 K (CO2), respectively. The variation of sorption capacity was studied as a function of burial depth of coal seams using the corresponding Langmuir parameters in combination with a geothermal gradient of 0.03 K/m and a normal hydrostatic pressure gradient. Taking the gas content corresponding to 100% gas saturation at maximum burial depth as a reference value, the theoretical CH4 saturation after the uplift of the coal seam was computed as a function of depth. According to these calculations, the change in sorption capacity caused by changing pressure, temperature conditions during uplift will lead consistently to high saturation values. Therefore, the commonly observed undersaturation of coal seams is most likely related to dismigration (losses into adjacent formations and atmosphere). Finally, we attempt to identify sweet spots for CO2-enhanced coalbed methane (CO2-ECBM) production. The CO2-ECBM is expected to become less effective with increasing depth because the CO2-to-CH4 sorption capacity ratio decreases with increasing temperature and pressure. Furthermore, CO2-ECBM efficiency will decrease with increasing maturity because of the highest sorption capacity ratio and affinity difference between CO2 and CH4 for low mature coals.

Explorer Article

Regions Tackle Challenges in 2011   
Vern Stefanic

What’s next? Leaders of three AAPG Regions talk about anticipated activity and potential challenges their areas face in 2011. 

Shales – Similar, Yet So Different  
Louise Durham

Going global: Not all shale gas basins are created equal – but countries all over the world are intrigued by the possibilities.

Algeria Sitting in a Sweet Spot  
David Brown

Europe needs a remedy: Years of worry about reliable gas supply from Russia has Europe looking north for gas exploration. Algeria may be just what the doctor ordered.

AAPG Explorer: A world of information  

Explorer Emphasis

U.S. Shale Expertise Now Being Exported  
Louise Durham

Deeper targets, higher excitement: Industry enthusiasm for shale gas (and oil) plays just keeps escalating – and the interest is going global.

German Geothermal Potential   
Barry Friedman

When it comes to geothermal energy, Germany is feeling the heat – literally and figuratively – beneath its feet.

Database Gathers Europe Shale Data   
Ken Milam

European researchers, inspired by gas shale successes in the United States, have started a database in hopes of finding similar success for their continent.

Field Seminar

Forum

Online e Symposium

Short Course

A wealth of industry information in a short period of time  
14 February 3000

Workshop

A collaborative exchange of ideas and and best practices  
14 February 3000
Coming Soon

Check back often. "Find an Expert" feature is coming online soon!