岩心核磁共振实验对低孔低渗碳酸盐岩储层的适应性研究

Evaluation of Core Samples from Low-Porosity and Low-Permeability Carbonate Reservoir with NMR Experiments

低孔低渗碳酸盐岩储层矿物成分复杂、岩石骨架参数难以确定、储集空间类型多样、孔隙结构及孔渗关系复杂、常规测井曲线响应特征不明显,使其测井评价极其困难.本文利用核磁共振测井定量评价低孔低渗碳酸盐岩储层岩心的孔隙结构、计算储层参数.利用T2谱分布曲线分析孔隙结构、计算T2截止值;在此基础上计算岩心总孔隙度、有效孔隙度、束缚水孔隙度、渗透率等储层参数,并与常规岩心实验结果进行对比分析;最后,总结出核磁共振测井在低孔低渗储层中的应用优势与局限,为核磁共振测井评价模型的建立提供基础数据.

Well logging evaluation of the low-porosity and low-permeability carbonate reservoir is difficult because of its complex mineral composition, difficult to determine rock skeleton parameters, diverse types of reservoir space, complex pore structure and pore-permeability relationship, and unobvious response characteristics of conventional logging curves. In order to quantitatively evaluate the pore structure and calculate the reservoir parameters by nuclear magnetic resonance(NMR) logging, NMR experiments on the core samples from low-porosity and low-permeability reservoir were performed.The pore structure was analyzed from the NMR data, and a T2 cutoff value was calculated using the T2 spectrum distribution curve. With the NMR method, the total porosity, effective porosity, bound water porosity, permeability and other reservoir parameters of the core samples were determined and compared with the results obtained with the conventional core experiments. The advantages and limitations of NMR methods in evaluating the low-porosity and low-permeability reservoirs were summarized.