多孔介质渗透率的NMR测定

摘要/Abstract

摘要：

介绍了利用NMR T₂弛豫数据求取岩心物性参数——渗透率的方法. 国外学者在分析了大量数据的基础上，建立了3种由T₂弛豫数据计算渗透率的模型，分别简称为SDR，Coates-cutoff和Coates-sbvi. 其中SDR模型不受束缚水计算方法的影响，但对岩心孔隙中流体的性质很灵敏，比较适合于水基泥浆地层. coates-cutoff和Coates-sbvi模型对束缚水的计算精度很敏感，可动和不可动流体孔隙体积的测定对渗透率的计算结果影响也很大. 此外，这三种模型对于低渗透率岩石的计算误差都较大. 通过对不同类型岩心的T₂弛豫特性和用常规方法测得的渗透率进行系统分析，在SDR模型的基础上所建立的渗透率测定方法（SDR-REV）有三个可调整参数，计算渗透率适用范围更大，计算的结果与常规实验值更接近. 把SDR-REV方法用于砂岩、砾岩、凝灰岩和火成岩四类岩心样品渗透率的测定，说明SDR-REV方法具有更普遍的适用性. 特别是对于中国普遍存在的低渗透岩心，测定结果更为准确.

关键词: 核磁共振(NMR), T₂弛豫, 测井, 岩心, 孔隙度, 渗透率, 模型拟合

Abstract:

The calculation methods for permeability of porous rock from its NMR T₂ relaxation distribution are introduced. There are three available models (i.e., SDR, Coates-cutoff and Coates-sbvi model). The Coates-cutoff model and Coates-sbvi model are very sensitive to the precision of irreducible fluid model, and thus the permeability results calculated by these two models are strongly affected by the precision of moveable/irreducible fluid volume calculation. On the other hand, the SDR model is not affected by irreducible fluid model, but it is sensitive to the property of the fluid in the core’s pores. Because there is only one variable coefficient in these models, the calculation errors are large when the permeability is very low. We found that the SDR-REV model, developed recently with three variable coefficients, is much suitable for calculating permeability of the core samples with lower permeability.

Key words: NMR, T₂ relaxation, well-logging, rock’s experiment, porosity, permeability, model fitting

中图分类号:

TE135⁺.1

彭石林, 叶朝辉, 刘买利. 多孔介质渗透率的NMR测定[J]. 波谱学杂志, 2006, 23(2): 271-282.

PENG SHI-Lin, YE Chao-Hui, LIU Mai-Li-. Measurement of Permeability of Porous Rock Using NMR T₂ Relaxation Distribution[J]. Chinese Journal of Magnetic Resonance, 2006, 23(2): 271-282.

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