页岩油气层核磁共振评价技术综述

NMR Technologies for Evaluating Oil & Gas Shale:A Review

对于常规储层,核磁共振是一项十分有效的解释—评价技术,它既能评价岩石物性与孔隙结构,又能评价孔隙流体分布与饱和度,且具有快速、无损、经济等特点;而对于页岩储层,其核磁共振受纳米级孔隙、复杂矿物成分、特殊孔隙结构、较高有机质含量、超低渗透性及内部梯度和受限扩散等因素的影响,面临探测分辨率低、解释模型不适用等瓶颈.为了发挥该项技术在页岩油气勘探开发中的作用,将国内外的页岩油气层核磁共振分析、评价技术与相关的页岩油气层实验室微观分析成果相结合,进行了系统梳理,从探测分辨率的提高、孔隙结构与岩石物性评价模型的建立、孔隙流体分布与识别模型的建立等方面进行了综述,提出需加强纳米孔的核磁共振弛豫机理和提高D-T2二维谱分辨率两个基础研究,在此基础上,进一步完善岩石物理及孔隙流体两个评价模型.

For conventional reservoir, NMR is an effective technology that can be used to evaluate petrophysics and pore structure, distribution and saturation of pore fluid rapidly, nondestructively and economically. Applying NMR technologies to evaluate shale reservoir, however, often encounters problems such as low resolution and inapplicable interpretation and evaluation models, due to reservoir characteristics such as nanoscale pore, complex mineral composition, complex pore structure, high organic content, ultralow permeability, influence of internal field gradients and restricted diffusion et al. In this paper, we reviewed recent progresses in NMR technologies for shale oil and gas exploration and exploitation, and related data analysis methods. Special attention was given to areas such as improvement of NMR detection resolution and novel evaluation models for pore structure, rock physical property, and pore fluid distribution and recognition. Two areas needed further research are identified： relaxation mechanisms inside nano-pore and improving pore scale resolution of D-T2. Petrophysics evaluation model and pore fluid evaluation model also need to be further optimized.