Coupled Seepage Mechanics Model of Coal Containing Methane Based on Pore Structure Fractal Features

• Published in: Fractal and fractional Vol. 6; no. 7; p. 391
• Main Authors: Lv, Runsheng, Zhu, Yuchen, Ma, Xinyu, Ni, Xiaoming, Ren, Jiangang
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.07.2022
• Subjects: Adsorption; Coal; coal body deformation; Coalbed methane; Deformation; Deformation effects; Experiments; fractal; Fractal geometry; Fractal models; Fractals; Heterogeneity; Mechanics (physics); Methane; methane-bearing coal; Morphology; Nitrogen; Permeability; pore; Pore size; Seepage; Strain
• ISSN: 2504-3110; 2504-3110
• DOI: 10.3390/fractalfract6070391

The paper applies fractal theory to the structure of fractal coal pores and calculates the fractal dimension and integrated fractal dimension for each pore section >100 nm, 100 nm > d > 5.25 nm, and <2 nm. In the experiment, we performed the full stress–strain-seepage experiment of methane-bearing coal, revealed the deformation–seepage characteristics of methane-bearing coal under load, and deduced the dynamic prediction mechanical model of methane-bearing coal permeability based on pore heterogeneity, followed by practical verification. The results show that the permeability change in methane-bearing coal is an external manifestation of coal pore deformation, and the two are closely related and affected by changes in the effective stress coefficient. The derived fractal-deformation-coupled methane permeability mechanics model based on coal pore heterogeneity has high accuracy, a general expression for the stress–strain-permeability model based on coal heterogeneity is given, and the fractal Langmuir model is verified to be highly accurate (>0.9) and can be used for coal reservoir permeability prediction.