Study On Numerical Simulation Of Gas-water Two Phase Flow Of Coal Seam

In China, the energy supply can not meet the needs of economic and socialdevelopment; energy has become a bottleneck restricting China’s rapiddevelopment. In the census of China’s new round of energy depth of the coalbedmethane resource is about less than2000m on coalfield that is about3.681billionm3, but most of the coal reservoirs are low permeability, and the coal seams is aporous medium, containing gas and water two-phase flow, while the existingmining technology under the application process can no longer meet the needs ofmining, there have been various problems, so study on coal bed methane-watertwo-phase transport mechanism to ease the development of technical problems it isimminent.Based on the theory of porous media fluid mechanics and rock mechanicsresearch in low-permeability conditions of coal bed gas-water meso seepagemechanism and antireflection measures, through the theoretical analysis of fluidtwo-phase flow, and established a general gas–water seepage of two-phase flowequations, and then researched special factors of the different particle radius of theporous medium under the conditions of permeability, porosity, saturation and theeffective radius of drilling etc. about main affect factors of CBM development.Through numerical simulation calculated and we find:(1) through meso numericalexperiments, the particle radius and porosity of the coal reservoirs in the mediachange, will affect the penetration rate of change;(2) pore fluid flow is far less thanthe fracture flow. Under starting pressure gradient effect, the penetration rate of thehorizontal direction is much larger than the vertical permeability, fluid migrationpathway is a fracture of the horizontal direction, vertical direction of migrationspeed is very low;(3) drilling for of coalbed gas-water flow under the action ofdrilling hole diameter75mm, the range of the effective radius of drainage is 0.8-1.2m through numerical simulation, the general about antireflection action ofcoal seam，the double drilling is better than the single-hole drilling, cross-drilled isbetter than parallel drilling, when the gas saturation at65%，under coal bedtwo-phase fluid flow phenomena，the part antireflection effect of the drilling isstagnation.According to the above results, it can be for low-permeability coalbed methanegas seepage mechanism research and the parameters of increased extraction toprovide a theoretical basis.