The Broad Concept and Resource Calculation Method of Coalbed Methane

2014 ◽  
Vol 962-965 ◽  
pp. 185-188
Author(s):  
Wei Hou ◽  
Fang Zhang
Keyword(s):  
Coal Seam ◽  
Calculation Method ◽  
Coalbed Methane ◽  
Surrounding Rock ◽  
Gas Content ◽  
Coal Bed ◽  
Broad Concept

It has become the focus of debate about Coalbed Methane (CBM) concept whether the surrounding rock is reservoir. The gas content of surrounding rock is considerable, and it may become valuable exploration targets. In lateral, the gas content of surrounding rock is negatively related with coal bed. In vertical, the closer distance between coal seam and surrounding rock is, the higher gas content is. The broad CBM is defined as the gas that mainly originates from coal, mainly exists in the coal seam, and also widely exists in the surrounding rock. The method of volume and capacity are used to resource calculation.

A Review of Technical Potential for Coal Production and Coal Degasification – A Conventional Source of Methane – In Nigeria

2003 ◽  
Vol 14 (1) ◽  
pp. 59-67
Author(s):  
Adepo Jepson Olumide ◽  
Ayodele Charles Oludare ◽  
Balogun Olufemi
Keyword(s):  
Coal Seam ◽  
Fossil Fuels ◽  
Underground Mining ◽  
Simple Calculation ◽  
Gas Content ◽  
Gelling Agent ◽  
Coal Bed ◽  
Natural State ◽  
Mining Operations ◽  
Inorganic Matter

Coal, a solid fuel in its natural state has been identified as one of the world's major fossil fuels. It is a compact, stratified mass of mummified plant debris interspersed with smaller amounts of inorganic matter buried in sedimentary rocks. The use of coal as an energy source can be dated back to the prehistoric times. Methane is associated with many if not all coal seams, and is the dreaded “fire damp” responsible for many pit explosions. Coal mines are designed to vent as much methane as possible. It is present in the pores of coal under pressure, released during mining operations and can be extracted through vertical well bores. This paper highlights the fact that pipeline- quality methane can be extracted economically from coal seems before and during underground mining operations. The stimulation method involves hydraulic fracturing of the coal seam by using water, sand and, a gelling agent in a staged and alternating sand/and no sand sequence. The purpose is to create new fractures in the coal seam(s). The cleating of the coal helps to determine the flow characteristics of the coal formation and is vital in the initial productivity of a coal-methane well. The simple calculation of gas-in-place is achieved by multiplying the gas content of the coal by net coal thickness, the density, and the aerial extent of the drainage. The method is claimed to be suitable for use in Nigeria and potential sites for coal bed methane extraction in Nigeria are identified.

Quantitative analysis of coal-bed methane components by downhole laser Raman spectroscopy

2021 ◽  
pp. 1-24
Author(s):  
Heng Wang ◽  
Lifa Zhou ◽  
Wang Yuxia
Keyword(s):  
Raman Spectroscopy ◽  
Coalbed Methane ◽  
Molecular Structures ◽  
Spectral Lines ◽  
Gas Content ◽  
Laser Raman Spectroscopy ◽  
Coal Bed ◽  
Laser Raman ◽  
Coiled Tubing ◽  
Ct System

Laser Raman spectroscopy can be used to acquire the unique fingerprint of a specific molecule, and it is widely used to identify substances and study the spectral line characteristics of molecular structures. The measurement of coalbed methane (CBM) content is essential in the exploration and development of CBM fields for optimizing the fracture design. For this purpose, laser Raman spectroscopy can be extremely beneficial because it detects the gas content rapidly and accurately. Moreover, conventional gas content testing methods are laborious, time-intensive, expensive, and yield inaccurate results. Therefore, we integrated a laser Raman spectroscopy system with a coiled tubing (CT) equipment for downhole deployment in gas wells to accurately determine the CBM content in situ. The developed system can directly determine the CBM content at a specific location in the target layer. The trace test characteristics enable this system to rapidly detect downhole gas components and contents. The real-time detection data are transmitted via a cable to a computer on the surface and are processed using a baseline correction algorithm and data enhancement algorithm. Fourier transform and wavelet transform are used to identify the Raman spectral lines, while analysis of Raman spectra is used to determine CBM content. By employing this equipment, we can shorten the cycle of depressurization, drainage, and recovery processes from multiple days to just a few hours. Furthermore, the integrated laser Raman spectroscopy-CT system enables a flexible operation and possesses strong site operability, making it suitable for complex and high-risk wells.

Study on Well Logging Technology with Methods of Evaluating Gas Content of Coal-Bed Methane Reservoir

2014 ◽  
Vol 1003 ◽  
pp. 183-187
Author(s):  
Huai Jie Yang ◽  
He Ping Pan
Keyword(s):  
Statistical Analysis ◽  
Coal Seam ◽  
Well Logging ◽  
Langmuir Equation ◽  
Gas Content ◽  
Coal Bed ◽  
High Yield ◽  
Coal Bed Methane ◽  
Analysis Method ◽  
Statistical Analysis Method

In this study, the well logging response of CBM reservoir have been analyzed, and discussing the factors that affect the gas content of coal seam. The well logging technology has been employed in connection with log data and gas content. Take one oilfield’s well logging data for example, statistical analysis method and Langmuir equation method are selected to calculate the gas content of one coal seam, the two calculated results are basically the same, the highest value are about 26 cm3/g, is a high-yield coal seam.

The Studies on Gas-Bearing Characteristics of Deep Coal Seams in Yanchang Oil and Gas Province, China

2014 ◽  
Vol 962-965 ◽  
pp. 213-216
Author(s):  
Guo Ping Jiang
Keyword(s):  
Coal Seam ◽  
Layer Thickness ◽  
Oil And Gas ◽  
Single Layer ◽  
Gas Content ◽  
Coal Bed ◽  
Coal Seams ◽  
Resource Potential ◽  
Gas Bearing ◽  
Average Layer Thickness

In this paper, four general directions are described to make evaluations and their resource potential; those are coal structure and coal level, gas content of deep coalbed, the coalbed thickness and distribution and the buried depth of coalbed. Coalfields of the study area are mainly Permian and Carboniferous coal seam of Shanxi Formation coal and Benxi group 11 # coal, coal seam depth 1370-1812m. No. 3 coal-seam average layer thickness of 1.6 m, the monolayer most 2 m thick; No. 11 coal-seam in the average layer thickness of 3 m, single-layer thickness of 4.5 m. Predict the amount of coal resources of 17.3 one hundred million t. Predict coal-bed methane resources of 27.68 billion cubic reserve abundance of 104 million square / km2 in. The exploration results show that this region has good development prospects.

Gas content of the D6 coal seam

2021 ◽  
Vol 101 (1) ◽  
pp. 18-25
Author(s):  
S.B. Imanbaeva ◽  
◽  
A.D. Mausymbaeva ◽  
V.M. Yurov ◽  
V.S. Portnov ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coalbed Methane ◽  
Underground Mining ◽  
Lower Layer ◽  
Complex Structure ◽  
Gas Content ◽  
Mining Operations ◽  
Coal Particles ◽  
The Difference ◽  
External Forces

The article deals with the issues of gas content of the most thick and stable D6 coal seam in the Tentek region. This complex structure seam is dangerous in underground mining for gas and dust outbursts, it consists of coal packs separated by interlayers of mudstones, while the lower layer 0.5-1.5 m thick is very soft, has a strong shear disturbance and is most saturated with methane. Extraction of coalbed methane is a necessary process to ensure the safety of mining operations, to reduce its emissions into the atmosphere, and to utilize it as a fuel and a product for obtaining synthetic materials. The regularity of changes in the particle size distribution of the upper thick pack and the lower thin pack indicates the difference in small coal particles in them, while there are much more of them in the lower layer therefore, the specific surface is larger, which is an important factor of the adsorption processes intensity in the accumulation of methane, and during the gas drainage from the seam. The activation energy of methane from carbohydrate has been determined. A quadratic relationship between methane gas evolution and its initial concentration has been shown. In carbohydrate, it depends on the energy of external forces. A complex relationship has been established between the gas pressure in the coal seam and its concentration and characteristics of the «coal-methanenatural moisture» system. Regularities of changing the methane content of the coal seam depending on its fracturing formed due to the effect of the energy of destruction and the energy appearing with increasing the area of a crack in the coal, have been obtained. The effect of the coal mineral composition on the gas content has been shown.

Low Rank Coalbed Gas Preservation Conditions of Inversion Study

2013 ◽  
Vol 448-453 ◽  
pp. 3747-3750
Author(s):  
Feng Long Huo ◽  
Cheng Wu Xu
Keyword(s):  
Coal Seam ◽  
Coalbed Methane ◽  
Prediction Method ◽  
Low Rank ◽  
Coal Bed ◽  
Accumulation Factor ◽  
Affecting Factors ◽  
Coalbed Gas ◽  
Lithology Prediction ◽  
Preservation Conditions

The preservation conditions of coalbed gas reservoir are one of the most important affecting factors. Coal seam roof and floor of coalbed methane is the most direct emission barrier. That is the direct control of coal seam gas accumulation factor. A coal seam roof lithology prediction method at present more popular is the wave impedance inversion. But the results have multiple solutions. While the technology of stratmagic seismic can be a very good solution to the traditional seismic attributes application problems. It can provide precise results for coal seam roof lithology prediction, providing geological basis for evaluation and development of coal bed gas.

Original design of coal-bed gas/air control units for engine-generator sets

2006 ◽  
Vol 220 (2) ◽  
pp. 179-184
Author(s):  
An-Ping Qiao ◽  
Yun-Qing Li ◽  
Feng Gao
Keyword(s):  
Coal Seam ◽  
Calculation Method ◽  
Combustion Engine ◽  
Control Unit ◽  
Coal Bed ◽  
Design Calculation ◽  
Original Design ◽  
Coal Seam Gas ◽  
Control Units ◽  
Generator Sets

An original air/fuel automatic mixing control unit for a coal-bed gas internal combustion engine and its matching generator, which is different from the conventional one, is introduced. The basic design and calculation method of this novel unit are explained. On the basis of these, the units of the 12V190ZDT type engine-generator sets are calculated and designed, machined, and trial-produced. A year's service-test at the Centre of West Coal Mine Construction shows that the performances of these devices are stable and reliable, and that this method could solve many practical problems that the old unit could not; for instance, working with mid-low concentration of coal-seam gas. They also fill a gap in the field of design, calculation, development, and application of coal-bed gas devices; the economic and social benefits are also truly remarkable. Therefore, the design and calculation method obtained in this article are important for engineering applications. This paper also offers a theoretical basis for the design and development of coal-seam gas engines or sets of engine-generator.

Research on Result Prediction of Coal-Bed Gas Wells Fracturing by Using Expert System

2013 ◽  
Vol 734-737 ◽  
pp. 1445-1449
Author(s):  
Chi Ai ◽  
Chao Yang Hu ◽  
Yu Wei Li ◽  
Feng Jiao Wang
Keyword(s):  
Expert System ◽  
Coal Seam ◽  
Hydraulic Fracturing ◽  
Gas Content ◽  
Coal Bed ◽  
Coal Bed Methane ◽  
Main Method ◽  
Number Of Factors ◽  
Coal Seam Thickness ◽  
Expert Database

Hydraulic fracturing is the main method to increase the output of coal-bed methane wells, however, the hydraulic fracturing result of coal-bed methane well is usually affected by large number of factors such as the conditions of coal-bed, the conditions of coal-bed methane well, fracturing operation parameters and so on. As a result, the fracturing operation result is difficult to predict. This paper assumed coal seam thickness, the depth of coal seam, coal seam gas content and other six main factors which affect hydraulic fracturing results by analysis various factors. Membership function of the expert system was established to divide the level of each factor. The established method which applies the expert system to predict the hydraulic fracturing results of coal-bed methane wells was based on expert database. Using the established expert system to calculate 200 groups of test data and the prediction error rate is only 3.5%. The prediction results are accurate and reliable, and can provide guidance for coal-bed methane wells fracturing optimization.

scholarly journals Study on Gas Enrichment Mechanism of Coal Seam Influenced by Vertical Stress on Mountainous Region Condition

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Xiaojie Yang ◽  
Ruifeng Huang ◽  
Shuhua Sun ◽  
Chaowen Hu ◽  
Bo Cheng ◽  
...  
Keyword(s):  
Coal Seam ◽  
Beam Theory ◽  
Vertical Stress ◽  
Surface Elevation ◽  
Gas Content ◽  
Coal Bed ◽  
Burial Depth ◽  
Mountainous Region ◽  
Vertical Pressure ◽  
Winkler Elastic Foundation

The controlling effect of vertical stress of mountainous region on gas occurrence of the coal seam below it has always been ignored. In order to clearly express its influence mechanism, the change laws of depth, stress, and permeability of coal seam pressurised by the overlying mountain were studied based on the Winkler elastic foundation beam theory and seepage theory in the paper. At the same time, the enrichment mechanism of the coal seam pressurised by the overlying mountain was analyzed. The results showed the following: (1) There was a significantly strong correlation between the stress, permeability change rule of the coal seam, burial depth, and surface elevation under such condition. (2) Under the action of the vertical pressure of the mountain, the stress and permeability distribution of the coal seam showed significant nonlinear characteristics. The stress was the greatest under the peak, and the permeability was the smallest. (3) The initial gas content value was controlled by the permeability and the stress of the coal seam in the situation. Moreover, the field practice showed that under the action of vertical pressure of the mountain, the evaluation law of gas content was coupling with the surface elevation of the overlying mountain. In addition, the gas emission change law during the excavation of the driving face also showed the same characteristics. The results might be of great significance for the development and utilization of coal-bed gas and the safe exploitation of coal resources.

scholarly journals Influence of Overlying Caprock on Coalbed Methane Migration in the Xutuan Coal Mine, Huaibei Coalfield, China: A Conceptional Analysis on Caprock Sealability

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Kaizhong Zhang ◽  
Qingquan Liu ◽  
Kan Jin ◽  
Liang Wang ◽  
Yuanping Cheng ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Coalbed Methane ◽  
Evaluation Method ◽  
Gas Content ◽  
Factors Affecting ◽  
Coalbed Gas ◽  
Huaibei Coalfield ◽  
Main Components ◽  
The Impact

In order to determine the controlling factors affecting coalbed gas migration in the Xutuan coal mine, Huaibei Coalfield, China, overlying caprocks with Quaternary and Neogene formation (loose bed), Paleogene formation (Redbed), and coal-bearing strata were investigated via petrography, lithology, and physical properties according to laboratory tests, theoretical analysis, and on-site exploration. Results indicate that the basic properties of coal were not significantly changed whereas the effect of coalbed gas escape was promoted in the presence of Redbed and loose bed. The pore structure analysis shows that Redbed has well-developed pore connectivity than coal-bearing strata (main components are sandstone, siltstone, and mudstone). Also, the diffusion coefficient and permeability of Redbed and loose bed are proved to be a little different than those of sandstone but are much higher than those of mudstone and siltstone. Based on the aforementioned findings, investigation on the sealing mechanism of overlying caprocks on CBM migration was further discussed, interpreting that the thickness, permeation, and diffusion features are crucial factors for sealing capacity of the overlying caprock. Thus, with the simplification on the thickness of overlying strata, a conceptional analysis was carried out to theoretically estimate the sealability of caprocks from surface drilling holes; it appears, though, that the master factor on coalbed methane accumulation is coal-bearing strata instead of Redbed and loose bed with a poor sealability. In this case, the reliability of the evaluation method could be indirectly validated from the on-site gas content data of the actual coal seam to fundamentally reflect the effect of Redbed and loose bed on gas-escaping, and the impact of coal-bearing strata on gas accumulation in the coal seam.

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