一利用格子Boltzmann方法计算页岩渗透率-中国石油大学学报.PDFVIP

2014年摇 第38卷摇 摇 摇 摇 摇 摇 中国石油大学学报(自然科学版)摇 摇 摇 摇 摇 摇 摇 摇 Vol.38摇 No.1 摇 第1期摇 摇 摇 摇 摇 摇 摇 摇 Journal of China University of Petroleum摇 摇 摇 摇 摇 摇 摇 摇 Feb.2014 摇 摇 文章编号:1673鄄5005(2014)01鄄0087鄄05摇 摇 摇 doi:10.3969/ j.issn.1673鄄5005.2014.01.013 一利用格子Boltzmann方法计算页岩渗透率 张摇 磊,姚摇 军,孙摇 海,孙致学 (中国石油大学石油工程学院,山东青岛266580) 摘要:针对页岩中孔隙主要分布在纳米尺度的特点,建立Knudsen数修正固体边界并考虑镜面反弹的格子Boltzmann 模型。 利用二维平板模型,考察Knudsen数对渗透率的影响,得出在一定误差条件下,须考虑Knudsen数修正的最大 孔隙宽度。 由页岩的SEM扫描图像重构得到三维数字岩心,利用新模型进行模拟流动,并计算得到绝对渗透率。 结 果表明:利用Knudsen数修正后,通道中间部分流体速度增大,固体边界处速度变小;压力不变,随着孔隙直径变小, Knudsen数增大,渗透率变小。 关键词:格子Boltzmann方法;页岩;Knudsen数;数字岩心 中图分类号:TE311摇 摇 摇 文献标志码:A Permeability calculation in shale using lattice Boltzmann method ZHANG Lei,YAOJun,SUN Hai,SUN Zhi鄄xue (College of Petroleum Engineering in China University of Petroleum,Qingdao266580,China) Abstract:Considering the nano鄄scale pores in shale,a lattice Boltzmann model amended by Knudsen number was estab鄄 lishedwith a specular bounceback condition onthe solidboundary. The effect of Knudsen number onpermeabilitywas stud鄄 ied in a2Dflatmodel. ThemaximumofporewidthcanbecalculatedwhentheKnudsennumberisconsideredatagivenrel鄄 ative errorrange. A3Ddigitalcoreof shalewasreconstructedusingSEMimages,whichwasusedtosimulatetheflowbehav鄄 ior in the core basedonthenewmodelinordertocalculatethepermeabilityofthecore. Theresultsshowthattheflowveloc鄄 ity in the middle of theflat model becomes larger after the model was amended by Knudsen number,whilethe velocity near the solid boundaries becomes smaller. Permeability decreaseswith the increase of Knudsen number when the pore diameter becomes smaller at the same pressure. Key words:lattice Boltzmann method;shale;Knudsen number;digital core 摇 摇 页岩气作为非常规油气资源日益受到重视,成 nm,页岩的孔隙直径