Analasis on effect of stress sensitivity on permeability of high-rank coal in southern Qinshui Basin

In order to realize the damage mechanism of stress sensitivity in coal reservoir, discuss the damage degree of high rank coal reservoir, 9 high- rank coal samples were collected in southern Qinshui Basin to complete the stress sensitivity measurement, and then the effect of stress sensitivity was systematic evaluated. Th e results showed that the damage degree of coal permeability of high- rank coal samples is large, main strong stress sensitivity. The permeability would decrease as a negative exponent with the surrounding stresses increase.The variation rate of coal permeability have the same trend with variation of the maximum damage rate. The permeability declined rapidly when the effective stress was lower than 9. 5 MPa, reflecting a strong stress sensitivity; while the permeability declined slowly when the ef fective stress was larger than 9. 5 MPa, reflecting a weak stress sensitivity. As a rule, how to avoid or decrease the permeability damage during the process of coalbed methane development is a key problem for achieving a high and stable gas production rate.