Dynamic Constitutive Relation Of Shale And Its Application

Better understanding of shale’s constitutive relationship under dynamic stress,the base of shale reservoir reforming,contributes to developing and stimulation of shale gas properly.In this paper, shale’s mechanical properties under dynamic stress are studied through the experiment--Split Hopkinson Pressure Test. Considering the main causes that affect shale’s dynamic constitutive relationship,shale’s dynamic statistical damage constitutive model is establishedbased on the statistical damage theory and experimental data.Then, the crack fracturing and propagation in the shale reservoir in the process of hydraulic fracturing are studied by applying the derived shale’s dynamic statistical damage constitutive model to the finite element analysis software. Good agreements are obtained on both the theoretical analysis and situational results against in-situ data. The research is-of great theoretical significance and application value in the development of shale gas.The thesis can be concluded as the following sections:1. The stress-strain curves (i.e. constitutive curves) under different strain rate are obtained and shale’s mechanical properties are analyzed by the SHPB impact experiment for shale;2. According to the experimental results, the shale’s constitutive model is established based on the statistical damage theory. Meanwhile, the model is modified after analyzing the effect of main model parameters. Then the comparison between the theoretical and experimental results is conducted to verify the feasibility of the constitutive model.3. Based on the fluid-solid coupling theory and the shale’s constitutive model, the mathematical model of crack propagation in the shale reservoir is established. Consequently, the mechanics of crack fracturing and propagation in the process of hydraulic fracturing is revealed.4. The established mathematical model is tested by numerical simulation on single well hydraulic fracturing. The fracturing and propagation mechanism in the. shale reservoir are analyzed. The shale reservoir sensitivity of multi-factors in the process of hydraulic fracturing is revealed by the parallel simulation...