Data of Evolution law and calculation model of shale permeability under true triaxial constant volumetric stress Conditions
Description
Data of Evolution law and calculation model of shale permeability under true triaxial constant volumetric stress Conditions
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To realistically simulate triaxial stress conditions, the volumetric stress of the shale sample was kept constant throughout the experiment. The initial stress state was defined as maximum principal stress σ1=60MPa, intermediate stress σ2=35MPa, and minimum stress σ3 =35MPa, with a total stress of σ1+σ2+σ3=130MPa. The σ2 coefficient started from 0 and increased stepwise by 0.1(Figure 3). The experimental design included four cases: Case 1: σ2 perpendicular to bedding, with σ3 constant; the σ2 coefficient increased by 0.1 each step, revealing the effect of fracture compaction on permeability when σ2 directly compresses bedding. Case 2: σ2 perpendicular to bedding, with σ1 constant; the σ2 coefficient increased by 0.1 each step, showing stronger permeability reduction under high strain differentiation, compared with Case 1. Case 3: σ2 parallel to bedding, with σ3 constant; the σ2 coefficient increased by 0.1 each step, revealing fracture propagation when σ2 is parallel to bedding. Case 4: σ2 parallel to bedding, with σ1 constant; the σ2 coefficient increased by 0.1 each step, showing more significant permeability enhancement under high strain differentiation, compared with Case 3.
Institutions
- Southwest Petroleum University