基于核磁共振谱图分段技术的流体性质识别方法研究

Study on the fluid property identification method based on NMR spectra segmentation technique

核磁共振录井近些年应用效果显著,可实现对现场岩石物性的快速分析,评价孔隙结构,定量分析含油气饱和度、可动流体饱和度、束缚流体饱和度等重要参数,但在流体性质识别方面,由于受T2截止值,以及可动流体、束缚流体饱和度及孔径分布等重要参数计算误差的影响,制约了核磁共振录井技术的进一步发展。通过引入核磁共振谱图分段技术(按照横向弛豫时间分段)对核磁谱图进行处理,依据重构的信号重新计算求取含油饱和度,并优选1~10 ms段含油饱和度与孔隙度建立二维解释图板,后期资料应用取得了较好的应用效果,解释符合率由75.6%提高到81.6%,提高了核磁共振录井解释评价精度,可满足现场快速识别流体性质的需要。

In recent years,NMR logging has achieved remarkable application effect,which can realize rapid analysis of field rock physical properties,evaluation of pore structure,quantitative analysis of important parameters such as hydrocarbon saturation,movable fluid saturation,and irreducible fluid saturation.However,in terms of fluid property identification,due to the influence of T2 cutoff value,there are slight errors in the calculation of important parameters such as movable fluid saturation,irreducible fluid saturation,and pore size distribution,which restrict the further development of NMR logging technology.The NMR spectra are processed by introducing the segmentation technique of NMR spectra(segmented according to transverse relaxation time),the reconstructed signal is obtained and calculated again,and the oil saturation and porosity in the 1⁃10 ms segment are optimized to establish a two⁃dimensional interpretation chart.The application of later data has achieved good results,with the interpretation coincidence rate from 75.6%to 81.6%,improving the accuracy of NMR logging interpretation and evaluation,which can meet the needs of rapid identification of fluid properties in the field.