分子扩散对枯竭油藏型地下储气库动态的影响

针对枯竭裂缝性油藏型储气库渗流特性非常复杂，许多矿场在应用和理论研究中往往忽略气体分子扩散对枯竭裂缝性油藏型地下储气库动态的影响。引入了Fick第一定律，对多孔介质中的扩散系数进行了修正，计算了气体扩散流量；并将气体分子扩散流量代到WarrenRoot双孔模型中，建立了考虑气体分子扩散的枯竭裂缝性油藏型地下储气库的数学模型，应用该模型进行了实例计算。算例分析表明：储气库运行18年后，考虑分子扩散比不考虑分子扩散自由气量多损失6％，累积产油量增加1.35倍；证明了气体分子扩散是储气库气体损失的一个重要原因，同时也是注气提高原油采收率的重要机理。

EFFECT OF MOLECULE DIFFUSION ON THE PERFORMANCE OF UNDERGROUND GAS STORAGE IN DEPLETED FRACTURED RESERVOIRS

The flowing characteristics of depleted fractured gas/oil reservoirs are very complex, effect of gas molecule diffusion on the performance of underground gas storage is often neglected in many field applications and theoretical researche. Authors of the paper firstly induce the Fick's First Law, correct molecule diffusion coefficient in porous media and calculate gas molecule diffusion flux rate, the calculated diffusion flux rate is then substituted in Warren-Root dural pore model to develop a new fractured underground gas storage mathematical model, which effectively considers the influence of gas molecule diffusion. The case-analyzing results of the new model show that after 18 years of operation, the cumulative losing free gas quantity in the gas storage with molecule diffusing is 6% more than that without molecule diffusion, while the cumulative oil production with molecule diffusion is 1.35 times more. It proves that the gas molecule diffusion is a key factor of gas lossing in gas storage, and also, is the important machanism of improving oil recovery by gas injection.