核磁测井资料在岩石粒度反演中的应用

The Application of NMR Logging Data in the Inversion of Rock Grain Size

吴进波 张海荣 陈现

WU Jinbo ZHANG Hairong CHEN Xian

中海石油（中国）有限公司湛江分公司，广东湛江　524057 南方海洋科学与工程广东省实验室（湛江），广东湛江　524300 中国石化石油勘探开发研究院无锡石油地质研究所，江苏无锡　214126

Zhanjiang Branch of CNOOC Ltd., Zhanjiang, Guangdong 524057, China Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Zhanjiang, Guangdong 524057, China Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, China

岩石粒度参数是储层岩石物理分析的关键评价参数。研究岩心核磁共振T2谱与岩石粒度分布曲线之间的关系，发现核磁共振T2分布与岩石粒度分布直接相关，因此可以利用核磁T2谱资料来反演岩石粒度分布。首先基于岩心实验结果对每块岩心采用分段非线性刻度转换方法由核磁T2分布计算岩石粒度分布，调整刻度参数使得计算得到的粒度分布与岩心分析粒度分布逼近，误差最小时即获得每块岩心的转换刻度参数。然后结合孔渗参数对岩心进行分类，确定每类岩心的刻度参数。最后根据实际核磁测井T2分布曲线对井下岩石粒度进行反演，反演结果与岩心分析结果对比效果良好，验证了方法的可靠性，为地质储层岩石物理分析提供准确的连续岩石粒度分布剖面。

Rock grain size parameter is the key parameter of reservoir rock physics analysis. The study of the relationship between NMR T2 spectrum and rock grain size distribution curve showed NMR T2 distribution directly related to and particle size distribution of rock. Hence NMR T2 spectral data can be used to retrieve the size distribution of rock. Firstly, based on the core experiment results, the rock particle size distribution is calculated from the NMR T2 distribution, using the conversion method of piecewise nonlinear calibration for each core, adjusting the calibration parameters to make the particle size distribution calculated approximate with the particle size distribution got thourgh core analysis, then obtain each core conversion scale parameter when error is minimum. Then classify the core and obtain scale parameters of each type according to the parameters of pore and permeability. At last, the granularity of down-hole rocks is inversed according to the actual NMR T2 distribution curve. It turned out that the inversion results fitted most core analysis results, which suggested the method is reliable and can provide accurate, continuous rock size distribution profile for geological reservoir rock physics analysis.

中海石油（中国）有限公司综合科研课题 "双孔介质储层测录井综合评价技术与作业方案优化研究"（项目编号：YXKY-2021-ZJ-01）

https://doi.org/10.3969/j.issn.1008-2336.2022.03.067