核磁共振T₂分布评价阳离子交换容量方法研究

Study on evaluation method of cation exchange capacity using NMR T₂ distribution

张冲¹ 张占松¹ 严伟²

长江大学油气资源与勘探技术教育部重点实验室，湖北 荆州 434023 中国石化勘探南方分公司勘探开发研究院，四川 成都 610041

MOE Key Laboratory of Exploration Technologies for Oil and Gas Resources, Yangtze University, Jingzhou 434023, China Research Institute of Exploration and Development, Exploration Southern Company, SINOPEC, Chengdu 610041, China

阳离子交换容量是基于泥质砂岩电阻率的含水饱和度解释模型中的关键项。文中根据含油气泥质砂岩体积模型和扩散偶电层理论，推导了阳离子交换容量与黏土束缚水孔隙度、总孔隙度和溶液矿化度之间的理论关系式。在此基础上，结合核磁共振实验和湿式的化学阳离子交换容量测试资料，提出了一种利用核磁共振T₂分布计算阳离子交换容量的方法。实际应用表明，利用该方法计算的阳离子交换容量与岩心分析结果吻合较好，证实该方法是可行的。这一研究成果对于扩展核磁共振测井储层评价应用具有参考价值。

Cation exchange capacity(CEC) is a critical item in the interpretation model of water saturation resistivity based on shaly sandstone. According to the volume model of oil-bearing and gas-bearing shaly sandstone and the diffusion double layer theory, the theoretical relationship among CEC and the porosity of clay bound water, the salinity of formation water and total porosity was derived. On this basis, a method of calculating CEC was put forward by using nuclear magnetic resonance (NMR) T₂ distribution combined with the data of NMR experiment and wet chemistry cation exchange capacity test. Actual data application shows that the result of CEC calculated by using NMR T₂ distribution coincides with that of core analysis, which confirms that the proposed method in this paper is feasible. The study can provide some references for extending application of NMR logging reservoir evaluation.

10.6056/dkyqt201205030