Pore structure characterization based on NMR experiment: A case from the Shanxi Formation tight sandstones in the Daning-Jixian area, eastern Ordos Basin

作     者：Yunxi Teng Chuang Er Jingzhou Zhao Qiqi Guo Congmin Shen Shijin Tan 

作者机构：School of Earth Sciences and EngineeringXi’an Shiyou UniversityXi’anShaanxi710065China Shaanxi Key Laboratory of Petroleum Accumulation GeologyXi’anShaanxi710065China 

出 版 物：《能源地球科学(英文)》 (Energy Geoscience)

年 卷 期：2023年第4卷第3期

页      面：266-275页

核心收录：

学科分类：081803[工学-地质工程] 08[工学] 0818[工学-地质资源与地质工程] 

基　　金：supported by the National Natural Science Foundation of China(41702132) 

主　　题：Pore structure Nudear magnetic resonance(NMR) Pore size distribution Fractal dirnension Irreducible water saturation 

摘      要：The study of pore structure requires consideration of important factors including pore throat size,pore radius composition,and pore-throat *** the nuclear magnetic resonance(NMR)experimental results contain rich information about pore structures and fluid occurrence states,this study investigated the pore structures of the tight sandstone reservoirs of the Shanxi Formation in the Daning-Jixian area,eastern Ordos ***,by making the inverse cumulative curve of the NMR T2 spectrum coincide with the capillary pressure curves which were obtained by the mercury injection capillary pressure(MICP)technique,this study derived a conversion coefficient that can be used to convert the NMR T2 spectrum into the pore throat radius distribution curves based on the NMR experimental ***,we determined the pore radius intervals corresponding to irreducible water distribution using the NMR-derived pore radius distribution ***,the NMR T2 distribution curves based on the fractal theory were analyzed and the relationships between fractal dimensions and parameters,including permeability,porosity,reservoir quality index(RQI),flow zone indicator(FZI),irreducible water saturation,RT35,and RT50,were also *** NMR-derived pore throat radius distribution curves of the study area are mainly unimodal,with some curves showing slightly bimodal *** irreducible water mainly occurs in small pores with a pore radius less than 100 *** the permeability decreases,the contribution rate of small pores to the irreducible water gradually *** NMR-based fractal dimensions of pores show a two-segment *** pores have small fractal dimensions and are evenly distributed,while large pores have large fractal dimensions and complex pore *** fractal dimension of large pores(Dmax)is poorly correlated with porosity but strongly correlated with FZI,RQI,RT35,and *** results indicate that large pores are the ma