Can cuttings replace cores for porosity and pore size distribution analyses of coal?

Chang, Yanhai; Yao, Yanbin; Liu, Yong; Zheng, Sijian

doi:10.1016/j.coal.2020.103534

Cited by 20 publications

(10 citation statements)

References 27 publications

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“…As discussed above, when P < P t , mercury has not yet occupied the intrapore volume of the coal samples, and thus the data were removed from the MIP data for a reliable pore structure characterization. The correction model of coal compressibility proposed by Li et al has been successfully used to correct the MIP data of coal at high pressure. ,, The correction process consists of two steps: first, calculating the matrix compressibility coefficients of coal and second, correcting the mercury volume caused by matrix compression. The matrix compressibility coefficients were calculated to be 3.82 × 10 –11 , 3.56 × 10 –11 , 3.77 × 10 –11 , 4.56 × 10 –11 , 5.30 × 10 –11 , and 1.53 × 10 –11 N –1 for S1–S6, respectively, which is close to the value of 7 × 10 –11 to 2.3 × 10 –10 N –1 reported for coal by Toda and Toyoda …”

Section: Resultsmentioning

confidence: 99%

New Model for Absolute Permeability Prediction in Coal Samples: Application of Modified Purcell Model to Mercury Injection Pressure and Nuclear Magnetic Resonance Data

Chang

Zhang

2023

ACS Omega

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The permeability of rocks is a critical parameter in many subsurface geological applications, and pore properties measured on rock samples (including rock fragments) can be used to estimate rock permeability. A major use of MIP and NMR data is to assess the pore properties of a rock in order to estimate the permeability based on empirical equations. Although sandstones have been extensively studied, permeability in coals has received less attention. Consequently, in order to obtain reliable predictions for coal permeability, a comprehensive study of different permeability models was performed on coal samples having a range of permeabilities from 0.003 to 1.26 mD. The model results showed that the seepage pores in coals account for the bulk of the permeability, while the contribution of adsorption pores to permeability is negligible. The models that only consider a single pore size point on the mercury curve, such as the Pittman and Swanson model, or those that use the entire pore size distribution, like the Purcell and SDR model, are inadequate for predicting permeability in coals. This study modifies the Purcell model to determine permeability from the seepage pores of coal, resulting in the enhancement of the predictive capability, with an increased R 2 and reduction in the average absolute error by approximately 50% compared to the Purcell model. To apply the modified Purcell model to NMR data, a new model was developed that provides a high degree of predictive capability (∼0.1 mD). This new model can be used for cuttings, which could lead to a new method for field permeability estimation.

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Section: Resultsmentioning

confidence: 99%

New Model for Absolute Permeability Prediction in Coal Samples: Application of Modified Purcell Model to Mercury Injection Pressure and Nuclear Magnetic Resonance Data

Chang

Zhang

2023

ACS Omega

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“…Some studies have found that the porosity measured on the same sample by the NMR- T 2 method exhibited good agreement with WIP method but was slightly lower than the GIP measured porosity, because a helium gas molecule has higher accessibility to pores than a water molecule . Unlike other methods, the NMR- T 2 measurement is independent of the sample size and shape . In addition, the NMR- T 2 porosity of a core plug can be measured at simulated reservoir conditions by replacing the measurement cell with a non-magnetic core holder, which can set different confining pressures.…”

Section: Characterization Of Pore Propertiesmentioning

confidence: 99%

“…104 Unlike other methods, the NMR-T 2 measurement is independent of the sample size and shape. 105 In addition, the NMR-T 2 porosity of a core plug can be measured at simulated reservoir conditions by replacing the measurement cell with a non-magnetic core holder, which can set different confining pressures. This is an advantage of the NMR-T 2 method over other methods that can only measure porosity at ambient temperature and atmospheric pressure.…”

Section: Characterization Of Pore Propertiesmentioning

confidence: 99%

Methods for Petrological and Petrophysical Characterization of Gas Shales

et al. 2021

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The increasing significance of shale gas resources to the global energy supply has resulted in an increasing need to understand shales as gas reservoirs. Shales commonly have complex organic and inorganic compositions and ultrafine pore structures. Fluid flow and transport in shale gas reservoirs (SGRs) are scale-dependent processes, including adsorption/desorption and diffusion of gas, water imbibition, and other non-Darcy flows, which is in contrast with conventional natural gas reservoirs, such as sandstones. In recent years, the transferring of the opinion from the prior efforts on studying the source and seal potential to the purpose of the function as the gas reservoir is creating some new challenges to the conventional analysis methods for SGRs. There has been a much larger number of publications relating to “shale and method” in the last 5 years compared to previously. On the basis of a review of these publications, this review summarizes both progresses made to improve or modify conventional methods as well as the application of new, emerging methods for a description of the complex shale petrology, rock physics, and flow mechanisms. The main part of this review is divided into six sections: organic geochemical evaluation, pore properties, such as pore type, porosity, specific surface area, and pore size distribution, wettability assessment, quantification of imbibition, gas adsorption and diffusion, and permeability evaluation. In each section, the advantages and disadvantages of conventional and emerging methods are reviewed. The goal of this review is to provide a guide for the reader to help them choose appropriate methods for future work in SGRs.

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“…The pores of the penetrated pore structure directly contact the external syngas and the syngas can flow through the penetrated pores. In addition, the molten slag droplet porosity (ϕ) can be estimated as where v p and v m represent the pore volume and the matrix volume, respectively.…”

Section: Model Descriptionmentioning

confidence: 99%

Numerical Simulations of Solidification Characteristics of Molten Slag Droplets in Radiant Syngas Coolers for Entrained-Flow Coal Gasification

et al. 2021

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The high-temperature syngas and molten slag droplets discharged from entrained-flow coal gasifiers contain a large amount of heat energy, which can be efficiently recovered by radiant syngas coolers (RSCs). However, it is hard to know the solidification degree of molten slag droplets at the outlet of an RSC during industrial operations. In this work, the industrial-scale RSC and molten slag droplet models are established to predict the solidification degree of slag droplets at the outlet of the RSC. Then, the effects of slag diameter, syngas flow field, slag initial temperature, slag porosity, and slag pore structure are investigated by numerical simulations, and residence time as well as complete solidification time are calculated by coupling of a discrete-phase model and a solidification model. The results indicate that as the slag droplet diameter increases, the residence time of the slag droplet shortens, but the complete solidification time increases. When the slag droplet diameter is greater than or equal to 3.0 mm, the complete solidification time is larger than the residence time, and the slag droplet cannot solidify completely at the outlet of the RSC. The solidification degree in the windward zone is greater than that in the leeward zone. Although the slag initial temperature has little effect on the solidification, a lower slag initial temperature is still conducive to a greater solidification degree. Additionally, the pore structure facilitates solidification, and the promoting effect of penetrated pores is more remarkable than that of closed pores. A larger porosity is also beneficial to accelerate the solidification of molten slag droplets and increase the solidification degree.

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Can cuttings replace cores for porosity and pore size distribution analyses of coal?

Cited by 20 publications

References 27 publications

New Model for Absolute Permeability Prediction in Coal Samples: Application of Modified Purcell Model to Mercury Injection Pressure and Nuclear Magnetic Resonance Data

New Model for Absolute Permeability Prediction in Coal Samples: Application of Modified Purcell Model to Mercury Injection Pressure and Nuclear Magnetic Resonance Data

Methods for Petrological and Petrophysical Characterization of Gas Shales

Numerical Simulations of Solidification Characteristics of Molten Slag Droplets in Radiant Syngas Coolers for Entrained-Flow Coal Gasification

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