利用核磁共振信息评价致密砂岩气层

Using NMR information toevaluate the tight sand gas reservoir

文章针对致密砂岩中,该类气层具有储层的成岩作用强,物性差,孔隙结构异常复杂、非均质性极强等特点,为解决该类气层的岩性识别、地质参数计算、流体判识以及孔隙结构分析是测井评价面临的难题。分析了核磁共振测井在致密砂岩地层评价具有特殊的规律,以岩样核磁共振实验分析为基础,阐述了核磁共振测井资料解决致密砂岩岩性划分、流体识别、地质参数计算以及孔隙结构分析等问题及解决方法。实践表明,核磁共振测井方法在致密砂岩天然气评价中具有较好的应用效果。

The gas reservoir in Neopaleozoic of GB region mainly distributes in the tight sand in the KuiShan segment of the up-ShiHeZi group.This type of gas is characterized by strongly diagenetic metamorphism,bad physical property,complicated pore structure and great anisotropy.Therefore,lithologic identification,geologic parameter calculation,fluid estimation and the pore structure analysis are difficult problem to well logging estimation.The NMR well logging bears special advantage in evaluating the tight sand.The NMR measures the T2 spectral distribution,which has intimate relationship with lithologic composition,fluid property,pore structure feature and gas content.This paper analyzes the NMR data and gives the methods for identifying lithology,calculating geologic parameter,estimating fluid and analyzing the pore structure,based on the NMR experimental analysis of the sample.The results demonstrate that NMR has good effect in the evaluation of the tight sand gas reservoir.