A new method for multi-exponential inversion of NMR relaxation measurements

Wang, Zhongdong; Xiao, Lizhi; Liu, Tangyan

doi:10.1360/03yw0111

Cited by 17 publications

(7 citation statements)

References 3 publications

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“…The NMR technique has been applied for formation evaluation purposes for several decades. The characteristics of fluid in the rock pores, effective porosity, permeability, movable and irreducible fluid volume, porous structure, and other geological information related to reservoir physical properties can be directly obtained by interpreting the NMR signals of hydrogen nucleus in fluid contained in the pores (Wang et al, 2001a;Weng et al, 2003;Al-Mahrooqi et al, 2003, 2006Tan and Zhao, 2006). Timur (1969) successfully applied the pulsed NMR to study the porosity, movable fluid, and permeability of sandstones.…”

Section: Introductionmentioning

confidence: 99%

Determination of movable fluid percentage and movable fluid porosity in ultra-low permeability sandstone using nuclear magnetic resonance (NMR) technique

Gao

2015

Journal of Petroleum Science and Engineering

197

100

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Section: Introductionmentioning

confidence: 99%

Determination of movable fluid percentage and movable fluid porosity in ultra-low permeability sandstone using nuclear magnetic resonance (NMR) technique

Gao

2015

Journal of Petroleum Science and Engineering

197

100

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“…NMR spectrums are obtained from magnetic decay data, and the inversion problem can be reduced to the first kind of Fredholm integral equation which is ill conditioned in the sense that small noise in the data can cause significant changes in the resulting spectrum. Common methods presented to solve ill‐posed inverse Laplace transform problems are iterative and regularized algorithms such as uniform‐penalty, Butter‐Reeds‐Dawson, truncated singular value decomposition, simultaneous iterative reconstruction technique (SIRT), nonnegative least squares, and intelligent optimization algorithms such as genetic algorithm, simulated annealing, differential evolution, Monte Carlo, and Lloyd‐Max optimal quantization (Borgia et al, ; Song et al, ; Sun, ; Wang et al, ). Different methods for 1‐D NMR inversion are suitable for various kinds of raw data.…”

Section: Theory and Experimentsmentioning

confidence: 99%

A Practical Method to Compensate for the Effect of Echo Spacing on the Shale NMRT₂Spectrum

Zhao

Zhang

et al. 2019

Earth and Space Science

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The low field nuclear magnetic resonance (NMR) technique is considered as one of the most effective methods to characterize the pore size and fluid distribution in geophysical prospecting. The signal of NMR is noninvasive and lithology independent, while the effect of NMR responses influenced by the echo spacing (T E ) is significant when applied to unconventional reservoirs which are featured with ultralow porosity and pore radius. T E is expected to be as low as possible to ensure most of the hydrogen signals are accounted for, but it is hard to achieve in downhole NMR measurement. We develop a practical method to compensate for the influence of T E on the transversal relaxation time (T 2 ) spectrum of shale. Based on the experiments with different T E , the relationship between the NMR calibrated porosity and the T E is established to recover the signal amplitude. The effect of T E on the peak position is investigated, and then an empirical equation is constructed to move the peak position to its original state. By the above two-step correction algorithm, the T 2 spectrums of shale at large T E are compensated precisely. The proposed method provides an effective way to obtain the real T 2 spectrum and achieves good results in the downhole NMR data processing of shale reservoir.

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“…The relaxation times of water in pore of different sizes are different. The clay-bound water, capillary-bound water, and movable water can be obtained by analyzing NMR log data [4,10] .…”

Section: Water Only In Poresmentioning

confidence: 99%

The influence factors of NMR logging porosity in complex fluid reservoir

Xie

Xiao²,

Wang³

2008

Sci. China Ser. D-Earth Sci.

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Porosity is a basic parameter for evaluating reservoir, and NMR logging is an effective method to obtain the porosity. However, we have often found that there exist significant differences between NMR porosities and formation core porosities in the complex reservoir. In this paper, we list the factors which affect the NMR porosity response in the complex reservoir, such as longitudinal relaxation time (T 1 ), transverse relaxation time (T 2 ), hydrogen index (HI) and borehole environment. We show how these factors affect the NMR porosity response and suggest methods to correct them. This should improve the accuracy of NMR logging porosity in complex reservoirs for the terrestrial formation.NMR logging, complex fluid reservoir, porosity, influencing factors Nuclear magnetic resonance (NMR) logging provides estimates on formation porosity with a technology which is superior to many of the conventional porosity logging methods, such as neutron, density and sonic logs. NMR logging gives quite accurate porosity in marine deposit or well sorted terrestrial sedimentation with little clay content 1) [1][2][3][4] . However, there exists significant differences between NMR and conventional log porosities in light hydrocarbon and /or heavy oil reservoir [5,6] . We analyzed several factors such as longitudinal relaxation time (T 1 ), transverse relaxation time (T 2 ), hydrogen index (HI) and borehole environment which could affect the NMR porosity response in the complex reservoir and suggest methods of correction to improve the results of NMR logging porosity.

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A new method for multi-exponential inversion of NMR relaxation measurements

Cited by 17 publications

References 3 publications

Determination of movable fluid percentage and movable fluid porosity in ultra-low permeability sandstone using nuclear magnetic resonance (NMR) technique

Determination of movable fluid percentage and movable fluid porosity in ultra-low permeability sandstone using nuclear magnetic resonance (NMR) technique

A Practical Method to Compensate for the Effect of Echo Spacing on the Shale NMRT₂Spectrum

The influence factors of NMR logging porosity in complex fluid reservoir

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A new method for multi-exponential inversion of NMR relaxation measurements

Cited by 17 publications

References 3 publications

Determination of movable fluid percentage and movable fluid porosity in ultra-low permeability sandstone using nuclear magnetic resonance (NMR) technique

Determination of movable fluid percentage and movable fluid porosity in ultra-low permeability sandstone using nuclear magnetic resonance (NMR) technique

A Practical Method to Compensate for the Effect of Echo Spacing on the Shale NMRT2Spectrum

The influence factors of NMR logging porosity in complex fluid reservoir

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A Practical Method to Compensate for the Effect of Echo Spacing on the Shale NMRT₂Spectrum