核磁共振录井参数与孔隙结构关系及其在长庆油田的应用

Relationship between nuclear magnetic resonance logging parameters and pore structure and its application in Changqing Oilfield

实验室的孔隙结构特征主要通过压汞曲线及孔喉半径频率分布图体现,而核磁共振t_2谱是岩心样品中不同孔隙流体核磁共振衰减信号叠加并经数学反演而成,能够反映孔隙结构特征。从理论上分析两者之间存在着关联性,通过研究核磁共振资料与压汞曲线及孔喉半径之间的关系,建立长庆油田储集层核磁共振t_2谱转换孔喉半径及压汞曲线方法,转换后与压汞资料具有较好的吻合性;通过研究核磁共振资料与表征孔隙结构的孔喉半径中值、排驱压力和分选系数之间的关系,建立长庆油田储集层核磁共振录井参数与孔隙结构之间的对应关系,实现两者定量转换,进而应用核磁共振录井资料可以评价储集层的微观孔隙结构,为录井从储集层微观角度进行油气层解释评价提供了依据。

The pore structure in the laboratory is mainly characterized by the distribution graph of intrusive mercury curve and the pore throat radius frequency,while the nuclear magnetic resonance(NMR) t_2 spectrum is obtained from the superposition of the nuclear magnetic attenuation signals of different pore fluid in the core samples and through mathematical inversion,which can reflect the pore structural features.Theoretically,there is a correlation between them.By studying the relationship between NMR data and intrusive mercury curve and pore throat radius,the conversion method of the NMR t_2 spectrum to pore throat radius and intrusive mercury curve was established for the reservoirs in Changqing Oilfield and after the conversion,it has good agreement with intrusive mercury data.By studying the relationship between NMR data and pore structure parameters,the corresponding relationbetween NMR logging parameter and pore structure of reservoirs in Changqing Oilfield was established to achieve a quantitative conversion between the two.Furthermore,the microscopic pore structure of the reservoirs can be evaluated by using NMR logging data,which provides the basis for mud logging interpretation and evaluation of hydrocarbon reservoir microscopic angle.