测井技术2026，Vol.50Issue(2)：316-326,11.DOI:10.16489/j.issn.1004-1338.2026.02.012
油基泥浆侵入低孔低渗储层核磁共振响应与残余油饱和度评价
NMR Response to Oil-Based Mud Invasion in Low-Porosity and Low-Permeability Reservoirs and Evaluation of Residual Oil Saturation
摘要
Abstract
To address the signal overlap between formation crude oil and oil-based mud(OBM)filtrate in nuclear magnetic resonance(NMR)logging T2 spectra and the consequent challenge in accurately evaluating residual oil saturation,this study focuses on low-porosity and low-permeability sandstone reservoirs in the Weixi'nan sag,Beibuwan basin.Online displacement NMR experiments are systematically designed and conducted to reveal the evolution of NMR T2 spectra after OBM filtrate invasion.Subsequently,a quantitative evaluation method for residual oil saturation integrating signal decomposition and constructed water spectrum is proposed.Experiments on 12 core plugs with diverse properties(porosity:3.17%～21.15%,permeability:0.01～29.5 mD,R2=0.713 1)reveal a consistent pattern:after OBM filtrate invasion,short relaxation components(T2<100 ms)decrease,while long relaxation components(T2>100 ms)increase.This establishes a characteristic distribution where formation water and crude oil signals concentrate in the short relaxation segment,and OBM filtrate signals dominate the long relaxation segment.Based on these findings,a combined approach is developed.First,asymmetric Gaussian functions and continuous wavelet transform enable high-precision decomposition of overlapping T2 spectra to separate crude oil and filtrate signals.Second,the constructed water spectrum difference technique eliminates filtrate contribution,allowing quantitative calculation of residual oil porosity and saturation.Application to severely invaded intervals in well B,Beibuwan basin,successfully identifies long relaxation signals as primarily OBM filtrate.Calculated residual oil saturations are below 10%,closely matching wireline formation test data and production test conclusions.This method effectively overcomes fluid signal overlap challenges in NMR logging under OBM invasion,providing a reliable technique for fine evaluation of residual oil saturation in low-porosity and low-permeability reservoirs drilled with oil-based mud.关键词
油基泥浆/核磁共振/残余油饱和度/T2谱/弛豫信号/低孔低渗储层Key words
OBM/NMR/residual oil saturation/T2 spectrum/relaxation signal/low-porosity and low-permeability reservoir分类
天文与地球科学引用本文复制引用
魏玺,王贵文,王猛,张志强,董宇..油基泥浆侵入低孔低渗储层核磁共振响应与残余油饱和度评价[J].测井技术,2026,50(2):316-326,11.基金项目
国家科技重大专项项目"大型智能化测井工业处理软件"(2025ZD1401100) （2025ZD1401100）
