Numerical simulation method and system for strength degradation of stratified shale

The invention discloses a numerical simulation method and system for strength degradation of stratified shale, and the method comprises the steps: preparing a plurality of shale samples, and obtaining the attribute parameters of the shale samples; drilling fluid is injected into one end of each shale sample within preset time, and the actual depth of the drilling fluid invading the shale sample bedding is measured; obtaining the compressive strength of each shale sample invaded into the drilling fluid, and fitting the compressive strength with the actual depth to obtain a first fitting relationship; constructing a physical model to simulate the simulation depth of the drilling fluid invading the bedding seam at different invasion time, and obtaining a second fitting relationship between the invasion time and the simulation depth; and performing equivalent substitution on the second fitting relationship and the first fitting relationship to obtain the strength degradation degree of the shale sample within the