摘要
孔隙结构是制约页岩气赋存与运移的重要因素。页岩致密、低渗,其孔隙度极低。酸液可溶蚀页岩中的部分矿物,使其孔隙增加,促进页岩内部的气体流动。论文利用稀盐酸、氢氟酸、混合酸分别对页岩试样进行了不同时间的酸化处理,应用扫描电镜(SEM)观测了酸化前后湖南牛蹄塘组页岩试样表面的孔隙。基于MATLAB对页岩酸化前后的电镜扫描结果进行了孔隙度分析,页岩试样孔隙度为10.68%,纯水、稀盐酸、氢氟酸、混合酸分别浸泡24 h后,试样孔隙度分别增加了1.21倍、1.3倍、2.61倍、2.99倍。利用扫描电镜能谱仪测试了酸化前后页岩的元素变化,分析了页岩试样与不同酸液反应的机理和反应程度。结果表明:1 h酸化后,氢氟酸作用后的页岩试样表面残有大量石英和黏土矿物;而混合酸作用后的页岩试样表面虽残有大量石英,但黏土矿物含量明显减小,混合酸液作用下黏土矿物更容易被溶蚀。混合酸溶液酸性最强,24 h酸化后,混合酸与石英和黏土矿物剧烈反应。混合酸作用后页岩的孔隙最为发育,促进了页岩渗透率的增加。
The ultra-low permeability and porosity of shale reservoir dominants gas storage and transport capabilities.Recent research shows that the acid solution would dissolve some specified minerals in shale matrix,improve the porosity together with the permeability,therefore and enhance the gas flow.The hydrochloric acid,hydrofluoric acid and mixed acid are applied to immerse the shale matrix with the SEM together with MATLAB applied to identity the porosity variation.Also the SEM and XRD are combined to measure the element changes before and post the immersion.The reaction mechanism and degree between shale samples and different acid solutions are analyzed.The results and discussions show the initial porosity of the shale matrix is 10.68%while enhanced to 1.21,1.3,2.61 and 2.99 times of the initial value after immersion.After soaking for one hour,a quantity of quartz and clay are remained on the surface of shale matrix after hydrofluoric acid immersion;and the content of clay minerals decreases obviously and lots of quartz remain when treated with mixed acid,which indicates that the clay minerals are more likely to be dissolved.After 24 hours of acidification,the mixed acid reacts violently with quartz and clay minerals because of its strongest acid.The porosity network is well developed after acidification with mixed acid prompting the gas reservoir performance.
作者
金佳旭
郑旭
付彦吉
陈天宇
杨冬鹏
仲红军
JIN Jiaxu;ZHENG Xu;FU Yanji;CHEN Tianyu;YANG Dongpeng;ZHONG Hongjun(College of Civil Engineering and Transportation,Liaoning Technical University,Fuxin 123000,China;Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines,Northeastern University,Shenyang 110819,China;Investigation and Design Institute of Water Resources and Hydropower Liaoning Province,Shenyang 110819,China;Drilling and Production Technology Research Institute of Liaohe Oilfield Company,Panjin 124000,China)
出处
《工程地质学报》
CSCD
北大核心
2021年第3期891-900,共10页
Journal of Engineering Geology
关键词
牛蹄塘组页岩
酸化
微观结构
孔隙度
矿物成分
Niutitang shale
Acidification
Microstructure structure
Porosity
Mineral composition
