Integrated Multifractal Framework for Characterizing Full-Scale Pore Architecture and Reservoir-Controlling Mechanisms of Deep Low-Rank Coal in the Turpan–Hami Basin

High Resolution Image Download MS PowerPoint Slide Understanding pore heterogeneity and its control on gas occurrence and migration in deep coal seams remains a critical challenge in coalbed methane (CBM) exploration. In this study, an integrated multifractal framework is proposed to characterize the full-scale pore architecture and quantify reservoir-controlling mechanisms of deep low-rank coals from the Turpan–Hami Basin. Comprehensive pore-structure characterization was conducted using high-pressure mercury intrusion, low-temperature N 2 adsorption, and CO 2 adsorption. Three coupled multifractal models─the pore-size distribution–fractal spectrum correlation model, the pore volume–fractal dimension coupling model, and the function–structure synergistic fractal model─were constructed to resolve multiscale heterogeneity, dominant pore types, and their effects on adsorption–seepage functionality. Results reveal a distinct “micropore–macropore dual-dominant” system, where micropores (>85% of surface area; 34.7–64.8% of pore volume across all samples) act as major adsorption sites, macropores (26.6–60.9% of pore volume) control seepage capacity, and mesopores ( 0.8 represents superior adsorption zones and D syn,1 > 0.6 marks high-efficiency seepage regions. This multifractal framework provides a strengthened theoretical and quantitative basis for evaluating deep coal reservoir quality and optimizing CBM production strategies.