二维核磁共振测井方法

TWO-DIMENSION NUCLEAR MAGNETIC RESONANCE LOGGING

核磁共振测井是通过对地层流体中氢核NMR信号的观测,获得用于地层评价所需的信息,然而目前的NMR测井都是基于一维核磁共振技术,只测量地层孔隙流体的横向弛豫时间T2信息,测量结果反映孔隙空间中的氢核总数,不能有效的区分这些信号是来自油还是来自水。当地层孔隙中油气和水同时存在时,它们的T2谱信号是重叠在一起的,使NMR测井技术在识别和定量评价油气水时存在很大的局限性。而二维核磁共振测井将孔隙流体中氢核数分布从一维空间的单个T2弛豫变量拓展到二维空间的两个变量,能够充分利用NMR观测的信息,开拓核磁共振测井岩石物理研究的新领域。本文介绍二维核磁共振测井的基本思想、方法原理以及反演方法,对二维核磁共振测井的研究具有重要的指导意义。

Nuclear magnetic resonance logging is to get the information for formation evaluation through measuring proton NMR signal of formation fluid.However,current NMR well logging is one-dimension nuclear magnetic resonance technique which measures only transverse relaxation time T2 of pore fluid.The measurement reflects the total of protons in pore but can not distinguish these signals from oil or gas.When there is oil,gas and water in the pore simultaneously,their T2 spectra signals are overlapped which makes NMR logging limited in identification and quantitative evaluation of oil,gas and water.While two-dimension NMR logging spreads proton distribution from one-dimensional to two-dimensional space.It extends the frontier of rocks physics research.The paper introduces the basic idea,principle and inversion method of NMR.It is of great significance to two-dimension nuclear magnetic resonance logging.