Fractal analysis of tight shaly sandstones using nuclear magnetic resonance measurements

Lai, Jin; Wang, Guiwen; Fan, Zhuoying; Zhou, Zhong‐Zhen; Chen, Jing; Wang, Shu-Chen

doi:10.1306/0425171609817007

Cited by 99 publications

(92 citation statements)

References 63 publications

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“…The Ordos Basin, located in the northwest of China with an area of 37.104 million km 2 (14.326 million mi 2 ), is the second largest sedimentary basin in China (Figure 1(a)) [2]. The margins of the basin experienced intense tectonic movements, while the interior basin, in areas where the rigid basement was developed, is characterized by deficient faults and folds and the strata slightly tilted to the west with a dip of less than 1° [4,27]. The Ordos Basin is tectonically bound by the Yimeng Uplift to the north, the Weibei Uplift to the south, the Xiyuan Thrust Belt to the west, and the Jinxi Fault-Fold Belt to the east.…”

Section: Methodsmentioning

confidence: 99%

“…where r max is the minimum value of the pore radius, in μm. Based on equation 6, the fractal dimensions of the pore structure from the intrusion method, defined here as the PCMI and RCMI tests, can be calculated [4,12,47]. Mercury is the nonwetting phase in the process of intrusion; hence, the mercury intrusion saturation with a pore radius larger than r in %ðS Hg ð>rÞÞ can be obtained.…”

Section: Fractal Analysis Theorymentioning

confidence: 99%

“…In view of the serious shortage of energy supply, tight sandstones have drawn much attention due to their considerable exploration and exploitation potential [1,2]. Expressing quantitatively the pore structures of tight sandstones, including heterogeneities of pore geometries, pore connectivity, and pore size distributions is becoming one of the most important works because an accurate description of pore structures is conducive to evaluating both storage capacities and percolation properties [3][4][5]. As complex geological materials, tight sandstones are dominated by nano-to millimeter-scale pores, making the characterization of the pore structure significantly different from those of conventional sandstones, and these sandstones have been paid much attention by the researchers [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…There has been a growing enthusiasm in employing fractals for comprehending the pore structures of tight formations. The fractal theory offers a successful prediction of the geometric morphology of porous media, builds up the relationships between microscopic pore system heterogeneities and macroscopic spatial qualities in sediments, and governs rules that simplify complex characteristics in nature [4,14]. By determining the fractal distributions of the tight sandstones, the topology of the pore space could be analyzed [15], the pore volume of different porous media can be quantitatively characterized [16,17], and the fractal dimensions of pore structures can also be used to relate the pore-scale understanding of the pore systems to core-scale measurements, such as porosity and permeability [4,11].…”

Section: Introductionmentioning

confidence: 99%

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Quantifying Fractal Dimension in Integrated Experimental Data of Tight Sandstones

Ren

Liu

et al. 2019

Geofluids

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Determining the microscopic pore structures of tight sandstones is becoming one of the most challenging efforts, and the strong heterogeneity makes the accurate assessment still a problem. In this research, we report a new criterion for pore structure typing based on the fractal geometry theory. The fractal dimension values were first accurately calculated through intrusion and nonintrusion methods. The results show that the pores in tight sandstones have multifractal distributions and different types of pore structure were divided based on various tests. The relationships between petrophysical properties and a series of multifractal parameters have been analyzed in detail. The fractal dimension values of type 1 sandstones derived from the throat curves in rate-controlled mercury intrusion methods can well characterize the porosity of the research area, while the others did not respond well. Finally, a multifractal criterion was proposed to analyze the petrological and pore structures by combined observations and experiments. The new criterion exhibits perfect performance in the prediction of the storage capacity. The multifractal model proposed in this research helps to assess the pore structures of tight sandstones and helps to characterize the reservoir quality in hydrocarbon exploration and development.

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Section: Methodsmentioning

confidence: 99%

Section: Fractal Analysis Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Quantifying Fractal Dimension in Integrated Experimental Data of Tight Sandstones

Ren

Liu

et al. 2019

Geofluids

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“…Pore structure significantly influences storage capabilities, transport properties, and oil‐bearing property in rock reservoirs . Sandstones typically have a wide range of pore‐throat sizes, spanning from the nanoscale (<1 μm) to the microscale; therefore, various techniques and theories must be applied to qualitatively and quantitatively describe the complex pore geometry and pore‐throat structure in sandstones . Mercury injection capillary pressure (MICP) experiments are widely used to determine the complexity and heterogeneity of pore‐throat distribution .…”

Section: Introductionmentioning

confidence: 99%

Effect of pore structure on oil‐bearing property in the third member of Paleogene Funing Formation in Subei Basin, East China

Liu

Xie

Shu

et al. 2020

Energy Science & Engineering

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Mercury injection capillary pressure (MICP) tests, nuclear magnetic resonance (NMR), (fluorescence) thin section, X-ray diffraction (XRD), and scanning electron microscope (SEM) analyses were used to describe the size and distribution of entire pore-throat structures in the sandstones of the E 1 f 3 (the third member of Paleogene Funing Formation) in the Subei Basin. The lithologies of E 1 f 3 in the Subei Basin are mainly dark-gray, very fine-grained sandstones and siltstones, interbedded with dark mudstones. The pore systems predominantly feature secondary intergranular and intragranular dissolution pores, micropores coexisting with minor amounts of intergranular pores, and microfractures. The high threshold pressure and bulk volume of irreducible fluids values and the significant variation in the NMR and MICP parameters indicate that the E 1 f 3 reservoirs are characterized by complex and heterogeneous microscopic pore structures. Microscopic pore-throat parameters are linked with macroscopic properties through the reservoir quality index (RQI). The NMR T 2 (transverse time relaxation) spectrum is unimodal or bimodal but with weak right peaks, indicating the rarity of large intergranular pores. However, large-scale pore throats, though only account for a minor part of the total pore volume, significantly contribute to the total permeability. The abundance of small-scale pore-throat systems (short T 2 components) results in high irreducible water content. Therefore, the oil saturation in E 1 f 3 sandstones is low, and the pore structure, especially the number of micropores, determines the oil-bearing property. Oil primarily occurs in the intragranular dissolution pores with minor amounts occurring in the large intergranular pores. Most of the micropores are bound by capillary water. The sandstones with chlorite clay minerals tend to be oil-wet and have high oil-bearing potential, while the abundance of detrital clay or illite contributes to a low oil-bearing grade. The combination of core and microscopic observations and the MICP and NMR analyses have allowed the determination of the pore structure characteristics and their coupling effects on oil-bearing property. |

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Review on Pore Structure Characterization and Microscopic Flow Mechanism of CO₂ Flooding in Porous Media

Tang

Hou

et al. 2020

Energy Tech

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Rapidly rising emissions of greenhouse gases into the atmosphere lead to the greenhouse effect and accelerate the exacerbation of the global climate. [1] Greenhouse gases include carbon dioxide (CO 2), ozone (O 3), nitric oxide (N 2 O), methane (CH 4), hydrogen fluoride, the chlorine carbide class (CFCs, HFCs, HCFCs), and perfluorinated carbide (PFCs) and sulfur hexafluoride (SF 6). The concentration of CO 2 is the highest in the atmosphere among greenhouse gases, and it significantly dominates global warming. [2] The process of the greenhouse effect and the impact of greenhouse gases on global warming are shown in Figure 1. Carbon is one of the most important elements of earth's structure and living things. It widely exists in the biosphere, lithosphere, hydrosphere, and atmosphere and circulates continuously with the movement of the Earth. CO 2 plays an important role in the cycle. Green plants absorb CO 2 from the atmosphere, and CO 2 is converted into organic matter and oxygen is also released through photosynthesis with the participation of water, as shown in Figure 2. [3,4] Before the industrial revolution, the carbon cycle has been kept in balance for millions of years. After the industrial revolution, human beings began to utilize fossil fuels to obtain energy. The balance of nature is thus destroyed, leading to climate anomalies (e.g., global warming) due to the increased concentration of CO 2 caused by the burning of fossil fuels and other industrial activities. Therefore, reducing emissions of CO 2 and other greenhouse gases is essential for protecting the natural environment. [5,6] At present, carbon emissions can be reduced by decreasing energy consumption, improving energy utilization efficiency, replacing fossil fuels with clean energy (e.g., solar energy, wind energy, geothermal energy, and hydrogen energy), and carbon capture and storage (CCS). However, it is still hard for most of the clean energy to completely replace fossil fuels in the near future because of safety, technology availability, and economical efficiency. [7] CCS is an important technological means to reduce carbon emission. [8,9] However, CCS requires high costs and may cause leakage of carbon because the captured carbon is usually sequestrated in saline aquifers, coal seams, depleted reservoirs, etc. [10-12] Therefore, carbon capture, utilization and storage (CCUS) has been acknowledged as a promising technology to achieve efficient reduction of carbon and also generate economic benefits, which is more practical and economical. [13] CO 2 is an important material for industry and has been applied in many fields, as shown in Figure 3. [14,15] In the food industry, CO 2 is used in the production of carbonized beverages, food preservation, and industrial processing as a refrigerant and protective gas. It can also be applied to synthesize chemicals, drugs, polymers, such as degradable plastics, etc. High-purity

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Fractal analysis of tight shaly sandstones using nuclear magnetic resonance measurements

Cited by 99 publications

References 63 publications

Quantifying Fractal Dimension in Integrated Experimental Data of Tight Sandstones

Quantifying Fractal Dimension in Integrated Experimental Data of Tight Sandstones

Effect of pore structure on oil‐bearing property in the third member of Paleogene Funing Formation in Subei Basin, East China

Review on Pore Structure Characterization and Microscopic Flow Mechanism of CO₂ Flooding in Porous Media

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Fractal analysis of tight shaly sandstones using nuclear magnetic resonance measurements

Cited by 99 publications

References 63 publications

Quantifying Fractal Dimension in Integrated Experimental Data of Tight Sandstones

Quantifying Fractal Dimension in Integrated Experimental Data of Tight Sandstones

Effect of pore structure on oil‐bearing property in the third member of Paleogene Funing Formation in Subei Basin, East China

Review on Pore Structure Characterization and Microscopic Flow Mechanism of CO2 Flooding in Porous Media

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Review on Pore Structure Characterization and Microscopic Flow Mechanism of CO₂ Flooding in Porous Media