摘要
中国尚处在页岩气勘探开发的初期,常用等温吸附实验获得吸附气含量来定量评价页岩气藏的品质和资源潜力。实验发现,随压力增加,吸附气含量不是一直增加的,而是呈现减小的趋势,甚至出现负值。对四川盆地及其周缘下寒武统和上奥陶统—下志留统48块样品的等温吸附实验研究表明,这一现象不是页岩吸附气含量的客观反映,主要和等温吸附实验原理、压力大小、自由空间体积大小、真实吸附气含量大小、微观孔隙结构和吸附剂等因素有关。高有机碳含量页岩由于其较高的吸附能力、且微孔和小孔不发育,自由空间体积增大导致的负吸附现象不明显;低有机碳含量页岩由于其较低的吸附能力、且微孔和小孔较发育,自由空间体积增大导致的负吸附现象明显。无论何种影响因素导致页岩的负吸附现象,均导致视吸附气含量比实际吸附气含量偏小,低估了页岩的赋存能力,页岩的实际吸附能力可能比我们实验获得的数据大得多。文章系统分析了页岩等温吸附曲线负吸附现象的原因,并提出校正建议,为页岩吸附气含量的准确测定和页岩气资源量的客观评价提供了依据。
China is still in the early stage of shale gas exploration and development.The isothermal adsorption test is commonly used to acquire adsorbed gas content and quantitatively evaluate the quality and resource potential of the shale gas reservoir.It is found that with increasing pressure the adsorbed gas content is not always increased,but shows a decreasing trend,or even negative.The isothermal adsorption test studies of 48black shale samples from Lower Cambrian and Upper Ordovician and Lower Silurian in Sichuan Basin and its surrounding areas have shown that this phenomenon can not objectively reflect the adsorbed gas content of shale.The negative adsorption phenomena is mainly related with the principles adapted in the isothermal adsorption test,the prevailing pressure,the size of the free space,the real adsorbed gas content,the microscopic pore structure,the adsorbents and other factors.Because of high adsorption capacity and nanoscale micropore are not developed in organic-rich shales,the negative adsorption phenomena caused by the increase in free space are not obvious;however,due to the low adsorption capacity and nanoscale micropore developed in organic-poor shale,the negative adsorption phenomena caused by the increase in free space are obvious.No matter what kind of impact factors caused the negative adsorption phenomena of shale it will lead to the apparent adsorbed gas content smaller than the actual adsorbed gas content.This negative adsorption underestimates the potential occurrence of shale reservoir.The real shale adsorption capacity may be much larger than the experimental data obtained.The present paper systematically analyzes the factors that caused the negative adsorption phenomena,puts forward the correction recommendations for the negative adsorption phenomenon and provides the basis for accurate determination of the adsorbed gas content of shale and for the objective evaluation of shale gas resources.
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2013年第6期282-288,共7页
Earth Science Frontiers
基金
国家自然科学基金项目(41202103)
国土资源部全国油气资源战略选区调查与评价专项(2009GYXQ15-02)
关键词
页岩气
吸附气含量
等温吸附
负吸附
自由空间体积
shale gas
adsorption gas content
isothermal adsorption
negative adsorption phenomena
free space
作者简介
聂海宽（1982-），男，博士，主要从事非常规天然气地质研究。E-mail：niehk．syky@sinopec．com
