Analysis on the Flow in Horizontal Coalbed Methane Well Under Coupling of Tilted and Horizontal Sections
It is of great significance to the selection of rational development technologies and equipment of horizontal coalbed methane well to precisely master the gas-liquid flow pattern inside the wellbore of horizontal coal-bed methane wells.Based on the gas-liquid flow theory,the computational fluid dynamics Fluent software simula-tion analysis method was used to analyze the variable state flow law in horizontal coalbed methane wells under the coupling of tilted and horizontal sections,The results show that the fluid flow in the updip section intensifies the fluctuation of the gas-liquid two-phase interface in the horizontal section.The liquid holdup in the horizontal sec-tion increases in the direction of fluid flow under high gas and liquid volumes,but decreases under low gas and liq-uid volumes.When the dip angle of the updip section is less than 20°,it has a great impact on the average liquid holdup in the horizontal section.In the lower horizontal section,the length and dip angle of the updip/downdip sec-tion affect the position of imaginary cross section in the horizontal section.Under the same flow conditions,the lar-ger the dip angle and length of the updip section at the outflow end,the farther the imaginary cross section to the updip section at the outflow end.The research results provide a theoretical basis for the design and optimization of withdrawl and recovery technology such as pump setting depth of horizontal coalbed methane wells.
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