基于核磁共振测井的致密气储层孔隙结构评价与分类

Evaluation of pore structure and classification in tight gas reservoir based on NMR logging

孔隙结构评价和储层类型划分对致密储层的勘探和开发具有重要意义.本文利用核磁共振测井对沙溪庙组致密气储层孔隙结构进行评价和分类.首先根据核磁共振T2分布形态利用模糊聚类的方法将致密砂岩储层孔隙结构分为Ⅰ、Ⅱ和Ⅲ类,随后结合压汞实验数据,利用变刻度幂函数法建立不同类型孔隙结构岩石T2分布转化毛管压力曲线的模型.根据建立的模型,我们将研究区实际核磁共振测井T2分布转化为毛管压力曲线,并计算储层孔隙结构参数,实现研究区致密气储层分类,通过岩心压汞实验数据和试油数据验证了储层分类结果的准确性.该方法可以扩展应用于其他地区致密储层的孔隙结构评价和分类.

Evaluation of pore structure and classification are of great significance for tight reservoirs exploration and development. In this paper, taking the tight gas reservoir of Shaximiao Formation as the research example. Evaluation the pore structure and classification based on Nuclear Magnetic Resonance(NMR) logging. First of all, the pore structure of tight reservoirs is divided into Class Ⅰ, Ⅱ, Ⅲ, by the fuzzy clustering according to the core NMR T_2 distribution. Then combined with the data of Mercury Injection Capillary Pressure(MICP) experiments, the MICP curve prediction model is established with different types of pore structures, based on the variable scale power function conversion method. NMR T_2 distribution was used to predict the MICP curve of tight sandstone according to the established model. Then calculate the pore structure parameters of the reservoir, and classify the reservoir in the study area. The accuracy of the reservoir classification results was verified by mercury intrusion data and test data. This method can be extended to pore structure evaluation and classification of tight reservoirs in other regions.