Acoustics tests are conducted on deep tight sandstone reservoir samples in Tazhong area. A new method is developed for quantitatively evaluating the microcrack stress sensitivity of tight sandstone reservoir using inversion of acoustic data. The fracture density and the aspect ratio are inversed by using the Biot consistent model and the DEM model

and the variations of and are discussed under different confining pressures. The stress sensitivity of microfractures are also evaluated. The results show that

with the increase of confining pressure

decreases and increases

mainly due to the closing of the microfracture. According to the reducing amplitude of under different confining pressures

the percentage of fractures that close or open can be determined. Samples with a larger under high confining pressure represent low stress sensitivity. Otherwise

the stress sensitivity is higher. This paper defines the point

where the pore-fracture in the rock changes greatly

as the turning point. The values of corresponding to the turning points of different samples are similar. This phenomenon can be seen as the common characteristics of tight sandstone reservoir fractures

and it can also act as the contrast indicator of the fracture development degree. The correlations of (with a confining pressure of 65 MPa) and turning pressure with rock porosity are discussed

which shows that they both have a very good positive correlation. For the deep low permeability sandstone reservoir in this region

the favorable fracture that has weak stress sensitivity is influenced mostly by physical properties of rock.