Study on effect of geo-stress on coal permeability and its controlling mechanism
Liu Dameng
Zhou Sandong
Cai Yidong
Yao Yanbin
Abstract：According to the great significance for the study on the effects of geo-stress on coal initial permeability and the expansion fractures during hydraulic fracturing,based on the controlling factors of stress state in coalbed methane (CBM) reservoir,the influence of geo-stress on the permeability and its controlling mechanism,the paper summarizes the recent progress about geo-stress vs.permeability.The results show that the influencing factors of geo-stress state include three aspects:tectonism,burial depth and coal lithotypes,dominating by the first and second aspects.The geo-stress generally captured by hydraulic fracturing method and experimental test.The current researches focused on the effects of in-situ tectonic stress field characteristics,laboratory and numerical simulation of different geo-stress on coal reservoir permeability.The essence of its controlling mechanism is the pore-fissure structure deformation in CBM reservoir dynamics.The regional stress field that developed a regional fissure system controls the regional distribution of coal permeability,whereas the local tectonic zone controls the anisotropic permeability in different blocks.The permeability decreases exponentially with increasing the effective vertical stress,the effective maximum horizontal principal stress and the effective minimum horizontal principal stress.Compared with the geo-stress difference,the coefficient of stress difference is the major factor that affects the expansion of hydraulic fracturing along the direction of maximum principal stress.
Keywords：geo-stressCBM reservoirfissurecoal seam permeability
Publication Date：2017-01-01
Pages：9( 1-8,23 )