2026-10-06T09:59:37Z https://api.figshare.com/v2/oai

oai:figshare.com:article/34037884 2026-10-01T03:03:28Z category_1 category_12 category_24 category_122 portal_63 item_type_6 month_year_10_2026

Microfracture Evolution and Transformation Mechanism of Coal Induced by Supercritical Carbon Dioxide Fracturing under True Triaxial Stress Conditions Xianglong Wang (3726340) Jienan Pan (1385547) Shike Zhang (6648329) Zhenzhi Wang (9727033) Qinghe Niu (14392086) Zhenfeng He (1555234) Biophysics Cell Biology Evolutionary Biology Mental Health two horizontal stress shaped connections promoted multiscale fracture network mineralized interface detachment injection flow rate important stimulation technology higher horizontal stress driven effects becoming seepage pathway development low stress difference high stress difference seepage capacity enhancement highest fracture connectivity h </ sub 2 </ sub seepage capacity difference conditions difference condition transformation mechanism results showed results provide natural fractures microfracture transformation mainly concentrated mainly characterized local closure intersection count image processing fractal dimension fractal analyses favorable conditions coal reservoirs coal induced became limited Supercritical carbon dioxide (ScCO₂) fracturing is an important stimulation technology for enhancing coalbed methane production, and microfracture evolution directly affects the seepage capacity of coal reservoirs. To reveal the evolution and transformation mechanism of ScCO₂-induced microfractures under true triaxial stress conditions, fracturing experiments were conducted under two horizontal stress-difference conditions and different injection flow rates. Image processing was used to analyze the distribution, structure, connectivity, and complexity of microfractures. The results showed that microfractures exhibited clear anisotropy after ScCO₂ fracturing. The maximum horizontal stress direction (σ_H) had the highest fracture connectivity and complexity and dominated fracture network development, whereas the minimum horizontal stress direction (σ_h) was mainly characterized by simple and isolated microfractures, and the vertical principal stress direction (σ_v) showed transitional characteristics. Under the higher horizontal stress-difference condition, fracture directionality became stronger, and complex microfractures were mainly concentrated in the σ_H direction, providing more favorable conditions for seepage pathway development. Connectivity and fractal analyses further showed higher connected microfracture area, intersection count, and fractal dimension in the σ_H direction. Injection flow rate and the principal-stress configuration jointly affected microfracture evolution. Under a low stress difference, increasing injection flow rate enhanced fracture connectivity and complexity. Under a high stress difference, fracture evolution first increased and then became limited, with fluid-driven effects becoming more pronounced at higher injection flow rates. SEM observations showed microfracture formation and propagation, mineralized interface detachment, and local closure. T-shaped connections promoted the connection between natural fractures and new microfractures, forming a multiscale fracture network. These results provide a basis for microfracture transformation and seepage capacity enhancement in coal reservoirs by ScCO₂ fracturing. 2026-09-30T00:00:00Z Text Journal contribution 10.1021/acs.energyfuels.6c03572.s001 https://figshare.com/articles/journal_contribution/Microfracture_Evolution_and_Transformation_Mechanism_of_Coal_Induced_by_Supercritical_Carbon_Dioxide_Fracturing_under_True_Triaxial_Stress_Conditions/34037884 CC BY-NC 4.0