Experimental Study on Rapid Determination Method of Coal Seam Gas Content by Indirect Method

Hong-yan, Lei; Dai, Linchao; Cao, Jie; Li, Rifu; Wang, Bo

doi:10.3390/pr11030925

Cited by 8 publications

(5 citation statements)

References 17 publications

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“…4,5 Gas content is normally measured using the direct method or the indirect method. The indirect method is limited in its use due to the complexity, long cycle, and low success rate of gas pressure measurement in coal seams, [6][7][8] while the direct method has been extensively applied by virtue of its advantages such as high measuring speed and broad applicability to complex geological conditions. 9,10 According to the direct method, coal seam gas content mainly involves three parts, namely gas loss, underground natural desorption, and residual gas content.…”

Section: Introductionmentioning

confidence: 99%

Gas desorption law of coal particles and calculation method of gas loss during fixed‐point closed sampling

Wen,

Wu,

Wei

et al. 2024

Energy Science & Engineering

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With the application of new technologies for coal mine gas control, it has been increasingly urgent to apply the fixed‐point closed sampling (FPCS) technology for accurate measurement of coal seam gas content. In this study, gas desorption during FPCS was analyzed. In addition, gas desorption experiments and COMSOL simulations were conducted on coal particles. Furthermore, the gas desorption law during FPCS was compared with that under atmospheric pressure. The results show that Sun's formula can effectively characterize the gas desorption law during FPCS, and the i value remains unchanged when the gas desorption curve is fitted with Sun's formula. On this basis, a specific method for calculating gas loss during FPCS by using Sun's formula was proposed. The research findings are expected to provide a theoretical basis for accurate measurement of coal seam gas content by means of FPCS.

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Section: Introductionmentioning

confidence: 99%

Gas desorption law of coal particles and calculation method of gas loss during fixed‐point closed sampling

Wen,

Wu,

Wei

et al. 2024

Energy Science & Engineering

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“…[8][9][10][11][12] The indirect method is based on the original gas pressure of the coal seam measured in the field and the value of gas adsorption constant determined in the laboratory and the results of industrial analysis, using the Langmuir equation to deduce the gas content. 13,14 This method requires the gas pressure value to be accurately measured. However, when drilling in the coal seam to determine the gas pressure, the process requirements are relatively strict, the cycle is long, and the success rate is limited.…”

Section: Introductionmentioning

confidence: 99%

Generation of cutting heat and simulation of coring tube wall temperature during coring in primary structure coal seam

MA,

Wang,

Yue

et al. 2024

Preprint

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When the drilling core method is used to determine the coalbed gas content, the cutting heat generated by the coring bit cutting coal will increase the coring tube temperature, and the excessively high coring tube temperature will have an heating effect on the coal core, which will accelerate the coal core gas desorption rate and increase the gas loss amount. The generation of cutting heat of coring bit and the measurement of coring tube temperature are the basis for grasping the gas desorption law of coal core and projecting the amount of gas loss. Firstly, the self-developed coring tube temperature measurement device was used to conduct on-site coring temperature measurement experiments at different cutting speeds. Then, the cutting temperature of coring bit was solved by establishing thermodynamic model for cutting coal and heat transfer model of cutting edge. Finally, based on the thermal conductivity characteristics of the coring tube, the coring tube temperature at different cutting speeds was simulated, and the simulated temperature was compared with the on-site measured temperature to verify the reliability of the model. The results show that when coring in primary structural coal, the temperature change trend of coring tube wall temperature measurement point at different cutting speeds is basically consistent, the temperature measurement point at the front end of the coring tube mainly goes through a relatively stable period in the drilling process, a sharp rising period in the cutting process, a slow rise and cooling period in the withdrawal process. However, the temperature measurement point at the back end of the coring tube wall mainly goes through a relatively stable phase and a slowly increasing phase. The temperature rise of the coring bit and the coring tube wall are significantly positively correlated with the cutting speed. When coring in hard coal seam and the coring depth is not large, the cutting heat generated by the coring bit and the coal body is the dominant factor for the temperature rise of the coring tube. The coring tube wall temperature calculated using the model matches well with the field measured temperature, and the error is small, which fully shows that the coring thermodynamic model is feasible. This study provides a basis for further research on the dynamic distribution characteristic of coal core temperature during coring, which is of profound significance to calculate the gas loss and coalbed gas content.

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“…Coal seam gas content is a key parameter in the exploration and development of coalbed methane resources, which can effectively predict the occurrence of protrusion, examine the effectiveness of regional antisurge, and evaluate the degree of coal mine gas hazard. – The methods of coal bed gas content determination are divided into direct method – and indirect method. , The process of the indirect method to determine coal seam gas content is complicated, the measurement period is long, and the success rate is low, so the direct method is mostly used to measure coal seam gas content underground in China. The direct method of measuring coal seam gas content mainly includes three parts: determination of gas desorption in underground coal samples, determination of residual gas in a laboratory, and extrapolation of gas loss during sampling, of which the first two parts can be measured according to relevant requirements, and the results are real and reliable.…”

Section: Introductionmentioning

confidence: 99%

Low-Temperature Response Characteristics of Coalbed Methane Desorption under High and Low Destruction Degrees

Zhu,

Wang,

Liang

2023

ACS Omega

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Freeze-coring technology can effectively reduce the amount of gas loss during the sampling process and improve the accuracy of gas content measurements in underground coal seams. In this study, high-and low-damage coals were selected as test objects to investigate whether the freezecoring technique is universally applicable to inhibit gas desorption in high-and low-damage coals. In this paper, the pore structure of the test coal samples was first tested using an ASAP2020 specific surface area analyzer, and then a nonfreezing and freezing simulation test was carried out on high-and low-damage coals using a self-developed freezing coring response test platform. The results showed that the gas desorption curves of both high-and low-damage coal samples followed the pattern of rapid increase in the early stage, slow increase in the middle stage, and stability in the late stage under both conditions; freezing conditions significantly reduced the gas desorption during the sampling process, and the difference in gas desorption between high-and low-damage coals was reduced; the gas desorption inhibition rate of high-damage coals was higher at an external heating temperature of 60 °C under freezing conditions; at an external heating at an external heat temperature of 90 °C, the gas desorption inhibition rate of low-damaged coal was higher in the early stage, and the gas desorption inhibition rate of high-damaged coal was higher in the later stage; freeze coring had a significant inhibition effect on the gas desorption of both high-and low-damaged coal types, which verified that the inhibition effect of freeze coring on the gas desorption of high-and low-damaged coal samples was universal. It provides a basis for the future application of freeze-coring technology in coal mines.

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Experimental Study on Rapid Determination Method of Coal Seam Gas Content by Indirect Method

Cited by 8 publications

References 17 publications

Gas desorption law of coal particles and calculation method of gas loss during fixed‐point closed sampling

Gas desorption law of coal particles and calculation method of gas loss during fixed‐point closed sampling

Generation of cutting heat and simulation of coring tube wall temperature during coring in primary structure coal seam

Low-Temperature Response Characteristics of Coalbed Methane Desorption under High and Low Destruction Degrees

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