NMR research of movable fluid and<i>T</i><sub>2</sub>cutoff of marine shale in South China

Zhou Shangwen; Liu Honglin; Yan Gang; Xue Huaqing; Guo Wei

doi:10.11743/ogg20160420

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NMR research of movable fluid andT₂cutoff of marine shale in South China
Vol. 37, Issue 4, Pages: 612-616(2016)
Online First：08 August 2016，

Published：2016
DOI： 10.11743/ogg20160420
稿件说明：

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DOI：

Zhou Shangwen, Liu Honglin, Yan Gang, et al. NMR research of movable fluid andT₂cutoff of marine shale in South China[J]. 2016, 37(4): 612-616. DOI: 10.11743/ogg20160420. DOI：

摘要

为了分析中国南方海相页岩气储层的可动流体及T

截止值特征，结合低场核磁共振和高速离心实验进行了页岩可动流体测试。实验结果表明：页岩饱和水状态和束缚水状态的建立至关重要，中国南方海相页岩建立饱和水状态的最佳压力为12MPa，建立束缚水状态的最佳离心力2.76MPa。其可动流体T

截止值为1.07～3.22ms，平均值为1.8ms，明显小于致密砂岩的T

截止值。使用经验值13ms来进行页岩可动流体的计算将会产生很大误差。结合饱和水状态和束缚水状态的核磁共振T

谱，得到可动流体饱和度为23.19%～30.84%，平均值为27.28%，束缚水饱和度高，超低含水饱和度现象明显。将核磁共振T

谱转换成孔径分布，得到页岩孔隙半径主要分布在20～200nm。

Abstract

Low field Nuclear Magnetic Resonance was combined with high speed centrifugal experiments to study movable fluids and T

cutoff values of marine shale in South China.The experiments reveal the importance of establishing water saturated state and irreducible water state for the calculation of movable fluids.For marine shale from South China

the optimum pressure for establishing water saturated state is 12MPa

and the optimum centrifugal force for establishing irreducible water state is 2.76MPa.The T

cutoff values range between 1.07ms and 3.22ms

averaging at 1.8ms

significantly less than that of tight sandstone.Therefore

using empirical value (13ms) for the calculation of movable fluids may result in great error.To deal with the problem

we integrated the T

spectrums of both saturated water state and irreducible water state to calculate movable fluid saturation.The result ranges between 23.19% and 30.84% (averaging at 27.28%)

indicating high irreducible water saturation and ultra-low water saturation.we also converted the NMR T

spectrum into pore size distribution

revealing the pore radius of shale to be within 20 and 200 nm range.