Petrophysical characterization of Chinese coal cores with heat treatment by nuclear magnetic resonance

Cai, Yidong; Liu, Dameng; Pan, Zhejun; Yao, Yanbin; Li, Junqian; Qiu, Yongkai

doi:10.1016/j.fuel.2013.02.031

Cited by 160 publications

(84 citation statements)

References 28 publications

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“…4. Finally, a horizontal projection from the cumulative curve is drawn at the irreducible water condition; the intersection of this projection line and the cumulative T 2 spectrum at water-saturated condition gives the T 2 cutoff (Cai et al, 2013). Eventually, the T 2 cutoff value, together with movable fluid parameters, can be determined by comparing the T 2 spectra obtained before and after centrifuging.…”

Section: Methodsmentioning

confidence: 99%

“…The drawback of T 2 measurement is that it is more complicated to interpret as it is affected by three possible relaxation mechanisms (i.e. the bulk, diffusion, and surface relaxations) (Cai et al, 2013). As for fluid flow in porous media, bulk relaxation and diffusion relaxation can be neglected.…”

Section: Introductionmentioning

confidence: 99%

“…T 2 cutoff corresponds to a threshold dividing the T 2 spectrum into two parts: bound water and free water; the free water corresponds to T 2 higher than T 2 cutoff. Accurate determination of T 2 cutoff is very important for determining bound and free fluid volumes, as well as pore throat distribution (Cai et al, 2013;Yao et al, 2010). The ratio of the T 2 coverage greater than T 2 cutoff to the overall T 2 coverage is called the movable fluid percentage (Wang et al, 2001b;Zhang et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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 usually uses the transverse relaxation time (T 2 ) to analyze the pore size distribution (PSD). The pores corresponding to the T 2 peaks are divided into adsorption pores, seepage pores, and fissures by Yao et al [11] and Cai et al [12]. They think that the patterns of unimodal, bimodal, and multi-peak in the T 2 spectra represent different pore types and PSD, and the pore characteristics of NMR were compared with those of MIP and CT scanning [13,14].…”

Section: Introductionmentioning

confidence: 99%

Experimental Analysis of Pore and Permeability Characteristics of Coal by Low-Field NMR

Song

Zhao

et al. 2018

Applied Sciences

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Abstract:On the basis of the complexity of the pore structure characteristics of a coal reservoir, coal samples with different ranks were selected to study the difference in pore structures and permeability using nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), and permeability measurement. Porosity and pore size distribution (PSD) above 20 nm can be analyzed by the improved NMR equation, and the results were basically consistent with that of SEM and MIP. The NMR spectra of the coal samples from the same location were close, but the difference between the coal samples from different locations was quite large, which indicated that the heterogeneity of a coal reservoir was strong. An empirical equation of movable fluid porosity was proposed, which can be used to evaluate the fluid migration characteristics of the coal reservoir, and the porosity of movable fluid mainly came from the contribution of fissures and micro-fissures. The average movable fluid porosity of the coal samples from the Chengzhuang (CZ) coal mine, Wuyang (WY) coal mine, and Yujialiang (YJL) coal mine was 1.37%, 0.67%, and 4.26%, respectively. Although the permeability is related to the NMR porosity and movable fluid porosity, it was difficult to establish a widely used mathematical equation correlating permeability and porosity based on the experimental data.

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“…Mohnke and Yaramanci (2008), Wang et al (2010), Li et al (2012, Cai et al (2013), Zhou et al (2013) and Ge et al (2013) analyzed pore radius distribution of various types of reservoirs using NMR methods, but they failed to intuitively describe and analyze the reservoirs' microscopic characteristics. Li et al (2008Li et al ( , 2012, Wang (2009), Yao et al (2010, Liu (2012), Mao et al (2013) and Zou et al (2013b) thought the results of pore radius distribution were consistent by contrasting NMR with mercury intrusion experiments/CT.…”

Section: Introductionmentioning

confidence: 99%

New characterization on the petrophysical characteristics of tight sandstone reservoirs in Yanchang Formation Ordos Basin China

Zhi-qiang

Shi

2016

Energy Exploration & Exploitation

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New characterization on petrophysical characteristics of tight sandstone reservoirs is of an important value to exploration and exploitation of oil and gas. In this paper, low-field nuclear magnetic resonance, combined with casting thin sections, laser scanning confocal microscopy, scanning electron microscopy and pressure-controlled porosimetry were applied to investigate the pore structure characteristics of nine tight sandstone samples of Yanchang Formation in the Upper Triassic Ordos Basin China. And then, based on the nuclear magnetic resonance T 2 spectrum distribution and previous theoretical models, a new model is proposed to predict permeability of tight sandstone reservoirs. Petrophysical characteristics are qualitativelyquantificationally analyzed by a combination of various experiments, which is considered to be a new method that will be widely used in future research. Results indicate that nuclear magnetic resonance T 2 spectrum distribution has a close relationship with characteristics of pore types and pore radius distribution. Three T 2 spectrum peaks are identified by the relaxation time at 0.1-10 ms, 10-100 ms and >100 ms correspond to micropores (<0.2 mm), mesopores (0.2-4.9 mm) and macropores and fractures (>4.9 mm), respectively, which is well consistent with results from casting thin sections, laser scanning confocal microscopy, scanning electron microscopy and pressure-controlled porosimetry. Compared with the existing several classical models, the new permeability model can better estimate the permeability of tight sandstone samples. The new characterization method and new model can accurately evaluate petrophysical characteristics of typical tight sandstone samples, which have a great value for nuclear magnetic well logging in the exploration and exploitation of tight sandstone reservoirs in the Ordos basin.

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Petrophysical characterization of Chinese coal cores with heat treatment by nuclear magnetic resonance

Cited by 160 publications

References 28 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

Experimental Analysis of Pore and Permeability Characteristics of Coal by Low-Field NMR

New characterization on the petrophysical characteristics of tight sandstone reservoirs in Yanchang Formation Ordos Basin China

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