The way of coalbed geology modeling is quite different from that of modeling conventional sandstone oil/gas reservoirs due to the following factors.(1)It is difficult to obtain the actual permeability of coalbed through laboratory experiment because the coal rock sample is brittle;(2)the permeability derived through laboratory experiments cannot reveal the subsurface conditions

since the coal rock is low in elastic modulus

high in poisson's ratio

and thus it is sensitive to stress;(3)it is difficult to apply the methods of well log petrophysical interpretation to interpret coalbed permeability.Thus in this study

we determine the permeability via well testing data

and establish a quantitative relationship between in-situ stress and permeability according to the types of coalbed

based on the analysis of all critical factors for permeability.In addition

we propose a 4-step modeling

namely

to set up the model of coal reservoir space framework

the coal facies(type)model

and the in-situ stress model.Then

under these 3 constraints

the model of permeability is established with stochastic simulation technique and the controlling points from the permeability obtained from well test and well in-situ calculation.Further

the model fits well with the production data status quo from the actual coal data of bed methane fields

which proves the feasibility of the concepts and methods in practical application.