摘要
以河南省新近系明化镇组热储层细砂为多孔介质,在水温40℃条件下,分别以Br-、NH4+为示踪剂开展室内土柱实验并采用CXTFIT2.1软件进行数据拟合研究其运移机制。首先通过Br-的穿透实验确定了土柱的运移参数,然后讨论了NH4+的运移机制。研究结果表明:填充土柱的弥散度为0.492 cm,较高的弥散度值与40℃的水温及填充土柱在一定程度上的非均质性有关。实测的NH4+的穿透曲线能和双点位吸附溶质运移模型预测结果较好地吻合。岩土对氨氮的阻滞系数较大为72.5,并且溶质的吸附存在速率限制步骤,这主要是因为低的达西流速及岩样中含有阳离子交换量极高的蒙脱石粘土矿物成分。
This paper is engaged in a study of the transportation mechanism of NH4＋ in the porous medium under geothermal environment. Column experiment of nitrate at 40 ℃ was done in the loose-pore geothermal reservoir matrixes, which were formulated in the Neogene Period in Minghuazhen Formation, Henan Province. The computer code CXTFIT was used to fit the experimental data. The transport parameters for the packed column were first determined through bromide displacement experiment, then the transportation mechanism of ammonium was studied at 40 ℃ and Darcy＇s fluxes of 3.6 cm/h. The results showed that the high value of＇the packed column＇s dispersivity could be partially attributed to the temperature and heterogeneity of the column, which was illustrated to some extent by the scanning electron microscope （SEM） picture of the porous medium in the column. The two-site nonequilibrium transport model can fit the observed breakthrough curve of ammonium well. The simulated retardation factor （R） was 72.5 which was much higher than the reported value. This could be attributed to the low pore-water velocity in the column experiments and montmorillonite in the porous medium, which has strong adsorption capacity and high cationic exchange capacity.
出处
《环境科学与技术》
CAS
CSCD
北大核心
2015年第4期74-78,共5页
Environmental Science & Technology
基金
河南省教育厅科学技术研究重点项目指导计划(13B610039)
河南理工大学博士基金联合资助(B2014-074)
关键词
多孔介质
地热水
氨氮
运移机制
porous media
geothermal water
ammonium
transportation mechanism
