The determination of surface relaxivity and application to coal spontaneous imbibition

Zhou, Hongwei; Sun, Xiaoming; Xie, Hui; Xue, Dongjie; Ren, W.G.; Liu, Z.L.; Li, X.N.; Hou, Wentao

doi:10.1016/j.fuel.2021.122165

Cited by 16 publications

(9 citation statements)

References 58 publications

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“…The SR of shales is influenced by many factors, such as pore geometry, mineralogical compositions, and magnetic susceptibility. Until now, numerous approaches have been established to capture the SR of reservoir rocks, which are summarized in Table . − At present, the most common approach is to appropriately match the T 2 distribution with the pore size distribution or S / V obtained by other approaches, such as MIP, N 2 , and centrifugation. However, none of them is universally accepted due to the reasoning mentioned above.…”

Section: Introductionmentioning

confidence: 99%

Determining Nuclear Magnetic Resonance Surface Relaxivity of Shales

2023

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Nuclear magnetic resonance, as an extensively recognized technique, is utilized to measure the pore size distribution of shales. However, the pore size distribution interpreted by nuclear magnetic resonance noticeably relies on the surface relaxivity (SR) of shales, which is influenced by many factors, including the measurement approach and mineralogical compositions. This paper chiefly deals with two approaches to measuring the surface relaxivity of shales based on a one-dimensional relaxation model. In continuing, the effects of mineralogical compositions and measurement approaches on the surface relaxivity of shales are methodically assessed. The surface relaxivity of shales is measured to be 1.34–2.59 μm/s by the spin echo approach and 1.40–2.44 μm/s based on the Carr–Purcell–Meiboom–Gill approach. Compared with the nitrogen adsorption approach, the suggested methods are more suitable for measuring the SR of shales. The achieved results reveal that the shale SR is negatively correlated with quartz and calcite and is positively correlated with pyrite and clay. In particular, the clay content seems to be the most vital mineral factor in determining the SR of shales.

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Section: Introductionmentioning

confidence: 99%

Determining Nuclear Magnetic Resonance Surface Relaxivity of Shales

2023

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“…Lu et al investigated the SI process with μ-CT, which reveals the relationship between the imbibition volume and fractures. The experimental study by Zhou et al illustrates that micropores play a key role in the early stage of SI and reach saturation first, followed by mesopores and macropores. Similarly, it is found that the average pore size of seepage pores is negatively correlated with the wetting range .…”

Section: Introductionmentioning

confidence: 99%

Quantitative Study of the Effects of Pore Structure and Wettability on the Water Spontaneous Imbibition Behaviors in Coal

Xu,

Zhai

et al. 2023

Energy Fuels

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Water injection has been widely used to prevent gas disasters and coal dust in coal mines. Coal would be wetted and softened by water through spontaneous imbibition (SI), which is mainly influenced by the pore structure and wettability. Studying the effects of pore structure and wettability on SI is of great significance for optimizing coal seam water injection parameters. This work aims to establish a quantitative relationship between these parameters and extract critical factors controlling the SI. Mercury intrusion porosimetry (MIP), low-temperature N 2 adsorption (LT-N 2 A), Fourier transform infrared spectroscopy (FTIR), and contact-angle measurements were used to assess the pore structure and wettability of the coal samples. Low-field nuclear magnetic resonance (LF-NMR) was used to monitor water in coal. All parameters were quantified with Pearson correlation analysis, and principal component analysis (PCA) was subsequently employed to pinpoint the key factors. The results show that the SI velocity and SI ability of bituminous coal are higher than those of anthracite; bituminous coal can rapidly elute more water. The time index (n) has a strong relationship with the SI velocity, and the higher the n value is, the faster the water migrates in pore space. Porosity is positively proportional to SI ability, and a larger SI ability means that the sample can store more water. The wettability parameter has a higher impact on SI velocity than on SI ability. Among the wettability parameters, the contact angle is a key factor in evaluating the SI process in coal. The bituminous coal with good pore connectivity, hydrophilicity, and high porosity could have a rapid SI velocity and store more water. Oxygen-containing functional groups promote SI by enhancing water and pore surface interactions. This work can better understand the mechanism of SI and provide the theoretical basis for field application.

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“…At present, scanning electron microscopy, CT scanning, MIP, nitrogen adsorption, and NMR technology 18−23 on the above testing techniques. Chang et al 24 and Zhou et al 25 used NMR technology to study the microscopic mechanism of moisture transport and permeability change during coal imbibition. Xia et al 26 monitored the mass change and distribution of water absorption during the imbibition experiment by using balance and NMR technology and studied the influencing factors of imbibition by using rock physical properties and fractal parameters.…”

Section: Introductionmentioning

confidence: 99%

Study on the Evolution Law and Mechanism of Fracture Imbibition in Loaded Coal Based on Micro-CT

Yu,

Li,

Gao

et al. 2023

Energy Fuels

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The determination of surface relaxivity and application to coal spontaneous imbibition

Cited by 16 publications

References 58 publications

Determining Nuclear Magnetic Resonance Surface Relaxivity of Shales

Determining Nuclear Magnetic Resonance Surface Relaxivity of Shales

Quantitative Study of the Effects of Pore Structure and Wettability on the Water Spontaneous Imbibition Behaviors in Coal

Study on the Evolution Law and Mechanism of Fracture Imbibition in Loaded Coal Based on Micro-CT

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