摘要
页岩富含纳米孔,纳米孔气体传输不同于宏观流体流动.基于滑脱流动和克努森扩散两种传输机理,分别以分子之间碰撞频率和分子与壁面碰撞频率占总碰撞频率的比值作为滑脱流动和克努森扩散的权重系数,耦合这两种机理,建立了理想气体传输模型.同时考虑高压条件下真实气体分子间相互作用力和气体分子自身体积对气体传输的影响,建立了页岩纳米孔真实气体传输模型.模型可靠性通过分子模拟结果验证.结果表明:纳米孔真实气体传输模型能够更合理地描述所有的气体传输机理,包括连续流动、滑脱流动和过渡流动;真实气体效应对气体传输的影响可高达23%,其受压力、温度、纳米孔尺度和气体类型的控制;在室内实验条件下模拟页岩纳米孔气体传输时,用氦气代替甲烷,低估了甲烷的传输能力65.09%;用氮气代替甲烷,高估了甲烷的传输能力106.27%.
The gas transport in nanopores of shale gas reservoirs significantly differs from that in conventional gas reservoirs. A model for ideal gas in nanopores is derived based on a weighted summation of slip flow and Knudsen diffusion, where ratios of molecule-molecule collisions and molecule-wall collisions to total collisions are the weighted factors of slip flow and Knudsen diffusion, respectively. This model is extended to the application of real gas transport in nanopores, taking into account the effects of molecule-molecule force and gas molecule volume on mass transport under the condition of high pressure. The model reliability is validated by published molecular simulation results. The results show that the model can be more reasonable to describe all of the gas transport mechanism known, including continuous flow, slip flow and transition flow; the real gas effect on gas transport is up to 23%, which is affected by pressure, temperature, nanopores radius and gas type; and transport capacity is underestimated by 65.09% with helium and overestimated by 106.27% with nitrogen in modeling methane transport in shale nanopores under the condition of laboratory experiments.
出处
《中国科学：技术科学》
EI
CSCD
北大核心
2016年第1期68-78,共11页
Scientia Sinica(Technologica)
基金
国家自然科学基金重大项目(批准号:51490654)
国家自然科学基金(批准号:51374222)
国家科技重大专项(编号:2011ZX05030-005-04)资助
关键词
页岩气
纳米孔
真实气体
滑脱流动
克努森扩散
shale gas reservoirs
nanopores
real gas
slip flow
Knudsen diffusion
