基于岩心核磁共振实验数据确定阳离子交换容量

Q_V Determination Based on NMR Testing Data

以HSK方程为基础,提出了一种利用岩心核磁共振实验数据计算阳离子交换容量QV的方法。该方法与湿式化学阳离子交换容量分析法相比存在一定的误差。12块岩样数据显示,相对误差范围12%～95%,平均相对误差为55%。分别从溶液矿化度、核磁共振总孔隙度以及黏土束缚水T2截止值等参数出发,开展了核磁共振确定阳离子交换容量影响因素分析研究。黏土束缚水T2截止值是影响核磁共振计算阳离子交换容量的关键参数,黏土束缚水T2截止值是可变的,而不是传统意义上的3ms。基于岩心核磁共振准确求取阳离子交换容量的前提是准确求取黏土束缚水T2截止值。

Based on the HSK equation, a calculation method ot cation excnange capacity （Qv） is proposed based on NMR test data. Compared with wet chemistry cation exchange capacity tests （CEC）, there is a certain error. 12 rock samples data show the relative error range is from 12% to 95% and the average relative error is 55%. To understand the impact factors of Qv determination based on NMR test data, the researches are carried out on solution salinity, NMR total porosity and clay bound water Tz cutoff values. The above results show that clay bound water T2 cutoff value is the key effect factor for accurately calculating Qv, its value is variable, rather than 3 ms as traditional understanding. The premise of accurately calculating Qv based on NMR testing data is to accurately calculate the clay bound water T~ cutoff value.