Characteristics of Coal-Powder Migration and Accumulation in Coalbed-Methane Wellbores Based on Physical Simulation

Abstract

The accumulation of coal fines in the wellbores of coalbed methane (CBM) wells is the result of gas-liquid-solid transport; it reduces the effective flow area, blocks drainage, damages equipment, and causes scaling and corrosion. The components of the physical simulation in this paper are particle entry, entrainment, migration, settling, wall interaction, deposition, resuspension and localised accumulation. The foundation of the above framework is the laws of conservation, particle force balance and evidence from peer-reviewed studies published between 2024 and 2026; no unverified experimental results have been used as facts. Primary influencing factors include agitation speed, gas-liquid ratio, particle size distribution, solids concentration, fluid properties, well inclination, wall conditions and local geometry. According to the above framework, changes in these factors will cause changes in the pressure gradient, transported-solids fraction, deposit mass, bed height and deposition location. Continuous deposition occurs in areas with a low local carrying capacity; thus, particles accumulate, the flow reverses, liquid holdup happens, and wall interaction strengthens. A similarity-aware transparent-loop experiment for synchronous pressure imaging and solids recovery can distinguish between transient holdup and steady accumulation. Therefore, the framework offers a way to explain the problem of blockage and separates facts from hypotheses and tests.