Abstract: Compared with shallow and medium-depth coal seams, deep coal reservoirs exhibit significant differences in gas–water occurrence, production mechanisms, and engineering responses. Under in situ high-pressure conditions, free gas primarily flows as a continuous medium, and variations in reservoir pressure and bottom-hole flowing pressure directly influence gas–water distribution, migration driving forces, and production evolution. Proper pressure management enhances gas production via matrix and fracture flow. Based on the control of coalbed methane (CBM) migration mechanisms by pressure evolution, an active depressurization and production control method centered on differentiated bottom-hole pressure regulation is proposed. This approach incorporates a critical fracturing fluid pressure model, criteria for iso-flow and iso-pressure points, and a dynamic gas–water ratio identification model, revealing the fluid migration characteristics and pressure-differential control rules across different production stages. A staged bottom-hole pressure management system—“safe flow initiation–stable dewatering–coordinated gas production–enhanced output and stable production”—is established, achieving dynamic coupling of pressure, flow mechanisms, and desorption kinetics throughout the production process. Numerical simulations based on typical CBM wells on the eastern margin of the Ordos Basin indicate that the active pressure-control strategy enables graded energy release and effective utilization of reservoir energy, producing a “multi-peak” daily gas production profile and improving predicted recovery by approximately 8.9% compared with uncontrolled conditions. Field tests further demonstrate that staged and graded depressurization effectively slows the pressure decline, mitigates rapid gas–water ratio increases, maintains two-phase flow balance, and gradually releases production capacity, significantly enhancing single-well output and production stability. These results provide a theoretical basis and practical guidance for the efficient development of CBM in deep coal-rock gas reservoirs of the Ordos Basin.

Key words: Ordos Basin, coal–rock gas, active pressure-reduction, equal flow point, gas–water ratio, numerical simulation