The invention relates to an evaluation method for describing the
compressibility of a shale reservoir. The evaluation method comprises the following steps that material contents including a well-site design report of a well to be evaluated, well-
logging materials and well-measuring materials of the well to be evaluated are collected; according to the collected materials, the shale reservoir and the vertical depth H of the middle of the shale reservoir are determined, the
fluid pressure gradient (FPG) of a stratum pore of the shale reservoir is determined, and the density (DEN) of stratum rock overlaying the shale reservoir is obtained; according to the FPG and DEN, the largest horizontal
crustal stress Kimax and the smallest horizontal
crustal stress Kimin of the shale reservoir are calculated; and the
diversity factor delta Ki of the horizontal
crustal stress of the shale reservoir is calculated, the
compressibility of the shale reservoir is evaluated, and an
evaluation result is output. The
diversity factor delta Ki of the horizontal crustal stress of the shale reservoir is calculated through parameters of the FPG, the DEN and the like, and the
compressibility of the shale reservoir is evaluated according to the
delta Ki. The evaluation method is applied in more than 300 wells among
shale gas wells in areas such as the middle Yangtze area, the Jiannan gas-field and the like, and the
verification coincidence rate of the staged fracturing effect is 97.1%.