As one of the most successful blocks of coalbed methane (CBM) development in Qinshui Basin

the exploration and development in Chengzhuang coal block can provide useful guidance for the development of other CBM blocks with geologically similar backgrounds.In combination of plenty of practical data on exploration and development and methods such as mathematical statistics

laboratory experiment

wire line logging interpretation

structure analysis

numerical modeling

decline analysis

we analyzed the genetic mechanism

accumulation conditions of CBM

and patterns of gas production

in the Chengzhuang Block.The study indicates that:(1) the Chengzhuang Block is characterized by favorable accumulation conditions with its simple structure

extensive reservoir distribution

shallow burial depth of coal reservoir

organic thermogenic gas

high gas content and high permeability;(2) the high productivity wells account for 47% of the total wells of the block

with high average production of 4 000~7 000 m

3

/d per well and high expected recovery of 55.1%.Furthermore

we analyzed the controlling mechanisms for CBM gas accumulation and high production

and concluded that (1) the tectonic thermal events would boost gas generation

reservoir quality

seal-capping capacity and optimal distribution of hydrodynamic force

which would be beneficial for CBM accumulation;(2) the coal reservoirs with horizontal extensional stress and in the coal mine pressure relief zone are of high permeability

favorable for CBM production.