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Title: Modelling of methane extraction from abandoned coal mines
Author: Martinez Rubio, Ruben
ISNI:       0000 0004 2743 3666
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2007
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This thesis describes the research undertaken to characterise abandoned mines in terms of permeability levels within an emission zone representative of post-mining conditions to model the rate of methane extraction using numerical tools. First, in order to create a general understanding about the flow regimes and pressure behaviour in abandoned mines during gas extraction a simple conceptual model was developed upon improvement of the pseudo-empirical void-resistance models currently employed by abandoned coal mine methane operators. The new model proposed a methodology to estimate the average residual gas strata pressure and residual mine void from extraction records. Upon validation the model identified the source of methane within an emission zone strata at nearly atmospheric conditions for leaky mines. Coal permeability zones around longwall faces are known from coal mining methane prediction methods to determine the rate of methane, discharge into operating coal mines. However, no reference to the extent, and permeability conditions, of the emission zone in abandoned coal mines has been made in the literature. A methodology to estimate the strata permeability levels around longwall panels was defined from previous laboratory studies on the permeability variation under different mining stress conditions. Numerical simulation results produced residual gas content profiles around longwall faces that were in agreement with empirical gas emission curves extensively used in methane prediction methods in different countries in Europe. The methodology defined to characterise the permeability conditions of coal and coal measure strata around longwall panels provided the foundation for the development of a new gas emission zone model incorporating the effect of multi seam mining in abandoned coal mines site. This approach was validated using METSIM, a modified CBM simulator to represent the 3-D models of Santa Barbara-Frankenholz abandoned coal mine in Germany and at the Bevercotes abandoned coal mine in the UK. The modelling results predicted the rates of methane production at the mine sites and provided reservoir information on gas reserve and pressure distributions.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available