Mass transfer in coal seams for CO₂ sequestration

Abstract

in Wiley InterScience (www.interscience.wiley.com).CO 2 sequestration in coal seams is a relatively new technique to simultaneously achieve enhanced coal bed methane production and reduced CO 2 emission. In this article, we integrate understandings in individual research fields to provide improved insight into the nature of this complex process. Our current overall model constructed from a number of sub-models consists of mass transfer in four pore types, namely, fractures, micro-, meso-, and macro-pores, all having pore size dependent characteristics. Key parameters are estimated using well established methods from the general literature. Three mechanisms of coal swelling leading to permeability variations during adsorption are proposed based on molecular simulations. The macroscopic level model is validated using a true tri-axial stress coal permeameter, which provides previously unpublished, accurate dynamic measurements of systems properties in three orthogonal directions including changes to the coal matrix volume. The integrated model provides a more complete and flexible representation for this complex system.

Sorption and changes in bulk modulus of coal — experimental evidence and governing mechanisms for CBM and ECBM applications

“…Technical details on the polyaxial system were reported earlier by Massarotto et al (2010), Wang et al (2007) and Wang et al (2010).…”

“…The work reported here is the result of a collaborative experimental program involving RWTH Aachen University, Stanford University, and the University of Queensland (related reports by Massarotto et al, 2010;Wang et al, 2007;Wang et al, 2010), and focused on the mechanical response and permeability evolution of coal in CBM/ECBM reservoirs. We subjected the sample to mechanical loading and unloading using a polyaxial compaction cell, first in the evacuated state, and then each time after exposing it to either helium, or sorbing N 2 , CH 4 , and CO 2 .…”

A model for enhanced coal bed methane recovery aimed at carbon dioxide storage

“…One dimensional models have been shown to provide a very useful understanding of the key mechanisms that affect the storage and recovery process (Gilman and Beckie 2000;Shi and Durucan 2003;Wang et al 2007;Jessen et al 2008;Seto et al 2009). One can distinguish up to four types of pores in coal, namely cleats where gas and water are present, macro-and mesopores where there is only free gas, and micropores where adsorption takes place.…”

“…Among these, gas sorption and swelling have complex effects on the displacement dynamics, whose accurate description is essential for the development of reliable reservoir simulators used to history match field test data obtained from ECBM field tests. Input for these models are the results of laboratory studies that have focused on the different aspects related to CO 2 storage in coal seams, namely gas sorption (Bae and Bhatia 2006;Day et al 2008a;Pini et al 2010), coal swelling (St. George and Barakat 2001;Day et al 2008b;Ottiger et al 2008) and permeability changes upon gas injection (Wang et al 2007;Mazumder and Wolf 2008;Pini et al 2009). …”

Three-dimensional carbon dioxide-induced strain distribution within a confined bituminous coal

“…Successful sequestration relies on many factors that are still poorly characterized (Holloway, 1997;Holloway, 2005). Most important factors include: porosity, permeability, sorption capacity and the magnitude of CO 2 -induced swelling or CH 4 /H 2 O removal-induced shrinkage of coal at in-situ condition (White et al, 2005;Wang et al, 2007).…”