Determination of nuclear magnetic resonance T2 cutoff value based on multifractal theory — An application in sandstone with complex pore structure

Ge, Xin; Fan, Yiren; Zhu, Xuejuan; Chen, Yiguo; Li, Runze

doi:10.1190/geo2014-0140.1

Cited by 121 publications

(70 citation statements)

References 24 publications

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“…Divide the study subject into N equal size box（N = 2 k ,k = 1,2,3….）, The scale of each box is ε, The probability mass function for the i th box with a scale ε can be expressed as follows:

ε = 2^{- k} L

P_{i} (ε) = \frac{N_{i} (ε)}{\sum_{i = 1}^{N (ε)} N_{i} (ε)}

where Ni ( ε ) is the cumulative porosity or pore volume of partition i , and Pi ( ε ) is the probability mass function and satisfy a power exponent relationship with the box scale ε , which can be expressed as:

{normalP}_{i} (ε) \propto ε^{- a_{i}}

…”

Section: Experimental and Multifractal Theorymentioning

confidence: 99%

“…The other set is q ~ D ( q ), which is introduced from the perspective of information theory. The formula of D ( q ) can be expressed as:

D (q) = \frac{1}{q - 1} \underset{ε \to 0}{falselim} \frac{\log \sum_{i = 1}^{N (ε)} P_{i}^{q} (ε)}{\log ε} = \frac{τ (q)}{1 - q}

…”

Section: Experimental and Multifractal Theorymentioning

confidence: 99%

“…For example, reservoir porosity and permeability, which vary from place to place, makes it difficult for the model to be widely used. Some researchers have also proposed T 2 cutoff value prediction models based on multifractal parameters . However, there are only multifractal parameters in the prediction model.…”

Section: Prediction Model For T2 Cutoff Value Calculationmentioning

confidence: 99%

“…In recent years, fractal theory has been applied to pore evaluation of porous media, including prediction of T 2 cutoff value . Fractal analysis theory has been gradually adopted as a new method to study nonlinear complex systems and used to study pore structure in rocks .…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, it has been a hot spot in pore evaluation. [12][13][14][15][16][17] The NMR T 2 contains a lot of information related to the fluid in porous media, including pore size distribution (PSD), and pore connection, 18,19 and can be used for pore structure evaluation, pore type characterization, capillary pressure reconstruction, calculation of porosity, and movable fluid saturation. 20 It is an important parameter for evaluating the reservoir properties of sandstone, shale, and coal.…”

Section: Introductionmentioning

confidence: 99%

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A method to determine nuclear magnetic resonanceT₂cutoff value of tight sandstone reservoir based on multifractal analysis

Guo

Zhang

et al. 2019

Energy Science & Engineering

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Nuclear magnetic resonance (NMR) T2 cutoff value is an important parameter for pore structure evaluation. It is complicated and uneconomical to obtain T2 cutoff value by an experimental method; therefore, it is necessary to explore a prediction method of T2 cutoff value. In this paper, 10 samples of tight gas reservoirs in the eastern Ordos Basin were selected, and then saturation and centrifugal experiments of nuclear magnetic resonance were carried out. On this basis, multifractal theory was introduced to calculate the multifractal characteristics of the NMR T2 spectrum of each sample, and the relationship between multifractal parameters and T2 value was analyzed. The influencing factors of the T2 cutoff value were clarified, and the prediction model of the T2 cutoff value was constructed accordingly. The results show that the T2 spectra of sandstones in the study area can be divided into three types: single steeple peak, double steeple peak, and irregular double peak. The pore diameter of the three types is 1 nm ~ 3×104 nm, 1 nm ~ 104 nm and 1 nm ~ 4×103 nm, respectively. The T2 cutoff value ranges from 9.72 to 35.16 ms. The correlation analysis suggests that the symmetrical fractal dimension difference and symmetrical multifractal dimension ratio (Dmin−Dmax, Dmin/Dmax) shows a positive linear correlation with the T2 cutoff value. The value of T2 cutoff gradually decreases with the increase of the flow zone indicator (FZI). Therefore, three parameters, including symmetrical fractal dimension difference, symmetrical multifractal number ratio, and FZI are optimized, and the prediction model for the NMR T2 cutoff value of sandstone samples in the study area is proposed. The introduction of porosity‐related parameters compensates for the shortcomings of previous T2 cutoff value prediction models. At the same time, the prediction model is proven to be accurate and reliable by testing the measured data of the samples near the study area. The results of this paper can be used for further study of the NMR T2 cutoff value prediction of tight sandstone reservoirs in different areas.

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ε = 2^{- k} L

P_{i} (ε) = \frac{N_{i} (ε)}{\sum_{i = 1}^{N (ε)} N_{i} (ε)}

{normalP}_{i} (ε) \propto ε^{- a_{i}}

…”

Section: Experimental and Multifractal Theorymentioning

confidence: 99%

“…The other set is q ~ D ( q ), which is introduced from the perspective of information theory. The formula of D ( q ) can be expressed as:

D (q) = \frac{1}{q - 1} \underset{ε \to 0}{falselim} \frac{\log \sum_{i = 1}^{N (ε)} P_{i}^{q} (ε)}{\log ε} = \frac{τ (q)}{1 - q}

…”

Section: Experimental and Multifractal Theorymentioning

confidence: 99%

Section: Prediction Model For T2 Cutoff Value Calculationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A method to determine nuclear magnetic resonanceT₂cutoff value of tight sandstone reservoir based on multifractal analysis

Guo

Zhang

et al. 2019

Energy Science & Engineering

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An improvement of the fractal theory and its application in pore structure evaluation and permeability estimation

Fan

Deng

et al. 2016

JGR Solid Earth

Self Cite

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We present an improved fractal model for pore structure evaluation and permeability estimation based on the high pressure mercury porosimetry data. An accumulative fractal equation is introduced to characterize the piecewise nature of the capillary pressure and the mercury saturation. The iterative truncated singular value decomposition algorithm is developed to solve the accumulative fractal equation and obtain the fractal dimension distributions. Furthermore, the fractal dimension distributions and relevant parameters are used to characterize the pore structure and permeability. The results demonstrate that the proposed model provides better characterization of the mercury injection capillary pressure than conventional monofractal theory. In addition, there is a direct relationship between the pore structure types and the fractal dimension spectrums. What is more, the permeability is strongly correlated with the geometric and the arithmetic mean values of fractal dimensions, and the permeability estimated using these new fractal dimension parameters achieve excellent result. The improved model and solution give a fresh perspective of the conventional monofractal theory, which may be applied in many geological and geophysical fields.

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Advances in Well Logging Techniques for Shale Reservoirs Exploration

Mukhopadhyay

2024

Advances in Oil and Gas Exploration &Amp; Production

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Determination of nuclear magnetic resonance T2 cutoff value based on multifractal theory — An application in sandstone with complex pore structure

Cited by 121 publications

References 24 publications

A method to determine nuclear magnetic resonanceT₂cutoff value of tight sandstone reservoir based on multifractal analysis

A method to determine nuclear magnetic resonanceT₂cutoff value of tight sandstone reservoir based on multifractal analysis

An improvement of the fractal theory and its application in pore structure evaluation and permeability estimation

Advances in Well Logging Techniques for Shale Reservoirs Exploration

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Determination of nuclear magnetic resonance T2 cutoff value based on multifractal theory — An application in sandstone with complex pore structure

Cited by 121 publications

References 24 publications

A method to determine nuclear magnetic resonanceT2cutoff value of tight sandstone reservoir based on multifractal analysis

A method to determine nuclear magnetic resonanceT2cutoff value of tight sandstone reservoir based on multifractal analysis

An improvement of the fractal theory and its application in pore structure evaluation and permeability estimation

Advances in Well Logging Techniques for Shale Reservoirs Exploration

Contact Info

Product

Resources

About

A method to determine nuclear magnetic resonanceT₂cutoff value of tight sandstone reservoir based on multifractal analysis

A method to determine nuclear magnetic resonanceT₂cutoff value of tight sandstone reservoir based on multifractal analysis