亚硝酸盐在明化镇组热储层中的转化规律研究

Study on transformation of nitrite in geothermal reservoir fine sand of Minghuazhen formation

以明化镇组热储层细砂为含水层孔隙介质,模拟地热水温度环境开展室内土柱模拟试验,研究不同温度条件下地热水亚硝态氮的转化规律,该研究为降低地热水中NO2-含量、地热水污染治理、修复及其可持续利用提供基础性科学依据.结果表明,细砂热储层中NO2-—N向NO3-—N,NH4+—N方向转化明显,是硝化作用和反硝化作用的共同作用,转化强度受温度影响较大,且40℃时NO2-积累的可能性比50℃时大.NO3-—N含量随时间变化趋势为,40℃时先迅速增高后逐渐降低,50℃时呈逐渐增高趋势.NH4+—N含量随时间变化趋势明显,40,50℃时均呈增高趋势,50℃较40℃增高快.TN含量随反应时间的增加呈降低趋势.两个温度下NO2-—N转化过程的pH值稳定在7.74～8.30,呈弱碱性,与反硝化作用强度有关;对应的DO值变化范围为2.88～3.78 mg.L-1,均随反应时间而有减小的趋势.

To study on the transformation of nitrite in a geothermal reservoir, the soil column experiments at different temperatures were carried out in the fine sand derived from a geothermal reservoir which was com- posed of Minghuazhen formation. The research can offer scientific evidence for reducing the content of NO2- , pollution management, repairing and providing sustainable utilization of the geothermal water. The results showed that the studied NO2--N in the simulated fine sand column was transfered to NO3---N and NH4＋--N at the same time and the temperature had an important effect on its conversion. The extent of accumulation of NO2 at 40 ℃ is more than that at 50 ℃. The content of NO3--N increased rapidly and then gradually re- duced at 40 ℃ while it increased gradually at 50 ℃. The content of NH4＋-N increased gradually at 40 ℃ and 50 ℃. On the contrary, the content of TN decreased gradually with time. The pH value fluctuated in the range of 7.74 - 8.30 which was related to denitrification. The DO （dissolved oxygen） value decreased with time and changed in the range of 2.88 - 3.78 mg. L-1