Experimental Investigation of Gas–Liquid–Solid Flow near the Pump Intake of Coalbed Methane Horizontal Wells

Sand deposition and gas ingestion near downhole pumps are persistent flow-assurance challenges in coalbed methane horizontal wells. A large-scale gas–water–sand flow loop was developed to investigate phase distribution, particle transport, and pump-intake behaviour under controlled gas and liquid flow rates, well inclinations, and progressing cavity pump speeds. Stratified flow dominated the horizontal configuration. Increasing gas flow generally lowered the gas–liquid interface and sand bed, while increasing pump speed increased outlet gas readings and recovered wet masses more clearly at higher gas rates. Local bed height did not consistently decrease with pump speed. Single-run comparisons at a liquid flow rate of 0.625 m3/h showed more intermittent liquid structures and lower outlet gas readings and recovered wet masses at 75° than at 90°. A four-coefficient semi-empirical model incorporated annular geometry and a pump-reference interfacial correction. Gas-group holdout RMSEs were 0.816 mm for bed height and 6.725 mm for liquid-layer thickness. Only 14 of 35 gas-held-out liquid-layer predictions were within ±10%. The model describes local phase heights within the tested horizontal geometry and operating range.