实际状态下的页岩气表观渗透率计算新模型

发布时间：2018-01-28 00:48

本文关键词： 实际状态页岩气表观渗透率计算模型黏滞流 Knudsen扩散吸附表面扩散渗透率比重　出处：《天然气工业》2017年11期 　论文类型：期刊论文

【摘要】：现有的页岩气表观渗透率计算模型均假设页岩气为理想状态,未考虑吸附气表面扩散等的影响,因而有可能与实际状态下的结果存在着差异。为此,针对实际状态下页岩气在纳米孔隙中的渗流情况,考虑了游离气的黏滞流、Knudsen扩散以及吸附气的表面扩散等影响因素,通过渗流力学方法,推导出了一种适用于实际状态的页岩气表观渗透率计算新模型;通过与实验测量结果的对比,验证了新模型的准确性,并利用所建模型分析了影响页岩气表观渗透率的各种因素。研究结果表明:(1)压力和孔隙半径对页岩气表观渗透率的影响最大,相对分子质量及阻塞系数对其的影响较小,Langmuir最大吸附量、Langmuir压力以及等量吸附热主要影响表面扩散渗透率比重;(2)在低压和高压条件下,各因素对表观渗透率及各渗透率比重的影响趋势存在着差异,低压下温度及孔隙半径对表观渗透率的影响更明显,同时温度、孔隙半径、Langmuir最大吸附量、Langmuir压力、等量吸附热等因素对各渗透率比重的影响也更明显;(3)压力较小、孔隙半径较小时,表面扩散占主要地位,压力较大、孔隙半径较大时,黏滞流占主要地位,小孔隙半径或低压条件下,表面扩散现象不可忽略。
[Abstract]:The existing models for calculating the apparent permeability of shale gas all assume that shale gas is an ideal state without considering the influence of surface diffusion of adsorbed gas, so it may be different from the results in actual state. In view of the actual seepage of shale gas in nano-pores, the influence factors such as viscous and stagflation Knudsen diffusion of free gas and surface diffusion of adsorbed gas were considered, and the percolation mechanics method was adopted. A new model for calculating the apparent permeability of shale gas is derived. The accuracy of the new model is verified by comparing with the experimental results. Various factors affecting the apparent permeability of shale gas are analyzed by using the established model. The results show that the pressure and pore radius have the greatest influence on the apparent permeability of shale gas. The relative molecular weight and blocking coefficient have little effect on the surface diffusion permeability. The maximum adsorption capacity of Langmuir, the Langmuir pressure, and the adsorption heat of the same amount mainly affect the specific gravity of surface diffusion permeability. 2) under the condition of low pressure and high pressure, the influence trend of each factor on the apparent permeability and the specific gravity of each permeability is different, the influence of temperature and pore radius on the apparent permeability is more obvious under low pressure, and the temperature at the same time. The influence of the pore radius and the maximum adsorption capacity of Langmuir on the specific gravity of each permeability is more obvious, such as the Langmuir pressure and the isobaric adsorption heat. (3) the pressure is small, the pore radius is small, the surface diffusion occupies the main position, and when the pressure is large, the viscous and stagnant flow occupies the main position, under the condition of small pore radius or low pressure. Surface diffusion can not be ignored.
【作者单位】：中国石油大学(华东)石油工程学院;成都理工大学能源学院;
【基金】：国家科技重大专项“鄂南长7页岩油流动机理及数值模拟技术研究”(编号:2017ZX05049-006) 国家自然科学基金项目“页岩油多尺度运移机制及数值模拟”(编号:51674279)
【分类号】：P618.13;TE642
【正文快照】： 页岩气储层以发育纳米级孔隙为主要特征[1],孔隙度一般小于6%[2],渗透率一般小于0.001 m D。目前,基于渗流力学方法建立的页岩气表观渗透率计算模型主要有Beskok-Karniadakis[3]、Javadpour[4-5]以及Klinkenberg[6]3种,而Jones-Owens[7]、Florence[8]、Ertekin[9]、Michel[10]

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