页岩气储层岩心孔隙度测量影响因素分析  

Analysis of influencing factors on porosity measurement of shale gas reservoir core

作　　者：李新[1,2,3] 刘鹏[2,3] 罗燕颖 方朝强[2,3] 李兵[2,3] 吴迪[2,3] 

机构地区：[1]西北大学地质学系,西安710069 [2]中国石油集团测井有限公司技术中心,西安710077 [3]中国石油天然气集团公司测井重点实验室,西安710077

出　　处：《地球物理学进展》2015年第5期2181-2187,共7页Progress in Geophysics

基　　金：中国石油天然气集团公司科学研究与技术开发项目(2012A-3908)

摘　　要：在页岩气储层柱塞状岩心孔隙度测量中发现一些特有的现象:用核磁共振法、液体饱和法和波义尔定律双室法三种方法得到的核磁孔隙度、盐水孔隙度和氦气孔隙度不能很好的对应,三者存在较大的差异,而在常规砂岩岩心中三者对应较好.利用不同分析方法研究了差异产生的原因,1)核磁孔隙度偏大的原因是页岩气储层岩心干样具有核磁信号,而干样核磁信号的来源是黏土矿物,主要为蒙脱石所含的大量层间水.2)、氦气孔隙度偏小的原因是页岩具有较强的吸附能力且大量发育纳米级微孔隙,导致其容易吸附空气中的氧气和氮气分子而堵塞,使测量气体未能完全充填页岩的微孔隙.3)洗油洗盐后的岩心具有亲水性,饱和液体法能使岩心完全饱和,充分反映岩心的孔隙空间.因此,在进行类似于页岩等黏土含量高、孔径较小的非常规油气储层岩心孔隙度测量时,应该以盐水孔隙度为准,重视黏土对核磁孔隙度、吸附对氦气孔隙度的影响,在此类非常规储层核磁测井时应充分考虑岩石本身的影响.The different phenomenon was found in plug core porosity measurement between the sandstone reservoir and the shale gas reservoir：good uniformity exists in Sandstone reservoir cores measured by NMR method,liquid saturation method and Boyle＇s double chamber method, but much differences exist in the measurement of shale gas reservoir cores.Analyze the reason of the phenomenon use different method,we got the following conclusions：First,the reason of that the NMR porosity in shale gas reservoir cores is more bigger is that the dry cores have a strong NMR signal,and the signal comes from the clay minerals,most is a large number of interlayer water that montmorillonite contained.Second,the reason of that the helium porosity in shale gas reservoir cores is smaller is that micro throats adsorbed of oxygen and nitrogen molecules in the air and blocked,results in measuring gas helium is not easy to enter the smaller pores.Third,sample after washing oil and salt were hydrophilic,saturated liquid method can make the core fully saturated so that the porosity is relatively more closer to its real value.Therefore,when we measured the porosity of unconventional oil and gas reservoir cores who is similar to shale gas cores that has high clay contents and the porosity and pore is smaller,we should take the porosity measured by liquid saturation method as the standard,pay attention to the clay and adsorption on the NMR porosity and helium porosity.When we use NMR logging in such unconventional reservoir should fully consider the influence of the rock itself.

关 键 词：页岩气 柱塞状岩心 孔隙度 核磁信号 黏土矿物 层间水 

分 类 号：P631[天文地球—地质矿产勘探]