Evaluation of Methane Dynamic Adsorption–Diffusion Process in Coals by a Low-Field NMR Method

Li, Zhentao; Liu, Dameng; Xie, Songbin; Fang, Xianglong; Si, Guangyao; Cai, Yidong; Wang, Yunpeng

doi:10.1021/acs.energyfuels.0c03168

Cited by 7 publications

(6 citation statements)

References 43 publications

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“…The first peak in the T 2 distributions in Figure arriving at or before 1 ms represents gas adsorbed to the core, which was the same as in a packed activated carbon column, crushed coal ,,, samples, and whole core samples, as described above.…”

Section: Resultsmentioning

confidence: 99%

“…The maxima of the first peaks are within a relatively small range, between 0.18 and 0.25 ms (Table 3), indicating the peak timing is controlled by the same process. The first peak in the T 2 distributions in Figure 4 arriving at or before 1 ms represents gas adsorbed to the core, which was the same as in a packed activated carbon column, 30 crushed coal 24,29,49,50 samples, and whole core samples, 27 as described above.…”

Section: Steady State Nmr Measurementsmentioning

confidence: 99%

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Quantifying Gas Storage and Transport in an Intact Core Sample Using Low-Field NMR and Pressure Measurements

Heagle,

Walsh,

Sgro

et al. 2023

Energy Fuels

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Quantifying gas movement through low-permeability rocks is important for shale gas resource evaluation as well as characterizing cap rocks for reservoirs storing natural gas, carbon dioxide, and hydrogen gas. In this study, we used an established NMRbased method to determine the ethane gas adsorption isotherm for an intact core plug of Bakken shale, with measurements carried out at 0.3, 1.4, 2.8, and 4.2 MPa. The results showed that there was ten times more ethane mass adsorbed to the sample compared to the ethane mass in the pores at 4.2 MPa. Next, we expanded the methodology to take advantage of the steady state between the core plug and gas in the NMR sample chamber at 4.2 MPa. The chamber was rapidly degassed to a gauge pressure of 0.061 MPa and shut-in. NMR measurements were used to quantify the gas adsorbed to the rock and the gas in the pores of the rock, while gas pressure measurements were made until the pressure reached a new steady state of 0.14 MPa after 21 h. The NMR measurements showed that one-third of the ethane measured at 4.2 MPa remained sorbed to the rock, indicating two-thirds of the ethane had desorbed. A numerical model of the degassing core was created by using TOUGH2 to simulate the desorption of ethane from the core and the movement of ethane out of the core by advection and diffusion. The model confirmed the affinity for ethane to remain adsorbed to the rock even when the pressure was lowered, suggesting enhanced gas recovery techniques may be required to remove a larger proportion of adsorbed gas in tight shale formations. The understanding of adsorption/desorption, permeability, effective porosity, and diffusion coefficient can be applied to reservoir models at reservoir conditions to improve estimates of gas recovery in tight rock reservoirs.

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Section: Resultsmentioning

confidence: 99%

Section: Steady State Nmr Measurementsmentioning

confidence: 99%

Quantifying Gas Storage and Transport in an Intact Core Sample Using Low-Field NMR and Pressure Measurements

Heagle,

Walsh,

Sgro

et al. 2023

Energy Fuels

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show abstract

“…The calculation results show that the increase of effective diffusion coefficients at a certain pressure drop rate induced higher desorption efficiency by stepwise pressure drop than by natural desorption. In addition, Li et al 26 investigated the methane adsorption under stepwise pressure drop using the NMR technique and calculated the micropore diffusion coefficient based on the bidisperse model and the dynamic diffusion coefficient based on the multiporous model for the adsorption process, respectively. The results show that their diffusion coefficients showed consistent variations, and the dynamic variation of diffusion coefficients was related to the combined effect of methane diffusion mechanism and coal matrix swelling under different adsorption pressures.…”

Section: Resultsmentioning

confidence: 99%

Review on the Application of Low-Field Nuclear Magnetic Resonance Technology in Coalbed Methane Production Simulation

et al. 2022

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Low-field nuclear magnetic resonance has become one of the main methods to characterize static parameters and dynamic changes in unconventional reservoirs. The research focus of this paper is process simulation of coalbed methane (CBM) production. The dynamic variation of pore volume with different pore sizes during pressure drop, methane desorption–diffusion process, and methane–water interaction during migration is discussed. Moreover, the calculation principles of NMR single and multifractal models are systematically described, and the applicability of NMR fractal models within different research contexts is discussed. Four aspects need urgent attention in the application of this technology in CBM production: (1) overburden NMR technology has limitations in characterizing the stress sensitivity of shale and high-rank coal reservoirs with micropores developed, and we should aim to enable an accurate description of micropore pore stress sensitivity; (2) dynamic NMR physical simulation of reservoir gas and water production based on in-situ and actual geological development conditions should become one of the key aspects of follow-up research; (3) low-temperature freeze–thaw NMR technology, as a new pore–fracture characterization method, needs to be further applied in characterizing the distribution characteristics of pores and fractures; and (4) NMR fractal model should be used as the main theoretical method to expand the simulation results. The applicability of different fractal models in characterizing pore–fracture structure (static) and CBM production process (dynamic) needs to be clarified.

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“…In previous research, we demonstrated that combination of gas adsorption and NMR can be used draw information regarding surface alteration [43]. Others have shown that these two techniques can be combined to understand the distribution of gasses in the pores and to gather information related to diffusion [153][154][155]. In addition, we are also confident that the hybridization of these two techniques can provide insights to better understand the capillary condensation process in shale complex porous media.…”

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confidence: 87%

Use of Gas Adsorption and Inversion Methods for Shale Pore Structure Characterization

Medina-Rodriguez

Alvarado

2021

Energies

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The analysis of porosity and pore structure of shale rocks has received special attention in the last decades as unconventional reservoir hydrocarbons have become a larger parcel of the oil and gas market. A variety of techniques are available to provide a satisfactory description of these porous media. Some techniques are based on saturating the porous rock with a fluid to probe the pore structure. In this sense, gases have played an important role in porosity and pore structure characterization, particularly for the analysis of pore size and shapes and storage or intake capacity. In this review, we discuss the use of various gases, with emphasis on N2 and CO2, for characterization of shale pore architecture. We describe the state of the art on the related inversion methods for processing the corresponding isotherms and the procedure to obtain surface area and pore-size distribution. The state of the art is based on the collation of publications in the last 10 years. Limitations of the gas adsorption technique and the associated inversion methods as well as the most suitable scenario for its application are presented in this review. Finally, we discuss the future of gas adsorption for shale characterization, which we believe will rely on hybridization with other techniques to overcome some of the limitations.

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Evaluation of Methane Dynamic Adsorption–Diffusion Process in Coals by a Low-Field NMR Method

Cited by 7 publications

References 43 publications

Quantifying Gas Storage and Transport in an Intact Core Sample Using Low-Field NMR and Pressure Measurements

Quantifying Gas Storage and Transport in an Intact Core Sample Using Low-Field NMR and Pressure Measurements

Review on the Application of Low-Field Nuclear Magnetic Resonance Technology in Coalbed Methane Production Simulation

Use of Gas Adsorption and Inversion Methods for Shale Pore Structure Characterization

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