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.

Geological Controls of the Coalbed Methane (CBM) Enrichment in the Zhengzhuang Coal Zone, Southern Qinshui Basin, China

2012 ◽  
Vol 616-618 ◽  
pp. 234-239 ◽  
Author(s):  
Jun Qian Li ◽  
Da Meng Liu ◽  
Yan Bin Yao ◽  
Yi Dong Cai ◽  
Xiao Qain Guo ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coalbed Methane ◽  
Adsorptive Capacity ◽  
Qinshui Basin ◽  
Coalbed Gas ◽  
Southern Qinshui Basin ◽  
Exploration And Development

For finding out favorable coalbed methane development districts, the evaluation of geological controls of CBM distribution and accumulation is essential during CBM exploration and development. In this paper, the No. 3 coal seam in the Zhengzhuang coal zone located at southern Qinshui Basin, China, was selected as a focus for comprehensively evaluating geological controls of CBM. The findings of this study are: (1) Coalbed gas contents increase with increasing mudstone roof thickness (ranging from 0-9 m), and will always be as high as 20 m3/t in the coal reservoirs with the mudstone roof thickness greater than about 9 m. (2) The weak transmission and stagnant coalbed water are favorable for CBM accumulation in coal reservoirs resulting from the typical hydraulic preservation of CBM. (3) High coalbed gas contents will commonly occur in vitrinite-rich and low-ash yield coals with high CH4 adsorptive capacity.

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.

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.

scholarly journals Numerical Simulation Research on Well Pattern Optimization in High–Dip Angle Coal Seams: A Case of Baiyanghe Block

2021 ◽  
Vol 9 ◽  
Author(s):  
Hongli Wang ◽  
Xiao Zhang ◽  
Suian Zhang ◽  
Hongxing Huang ◽  
Jun Wang
Keyword(s):  
Coal Seam ◽  
Coalbed Methane ◽  
Horizontal Well ◽  
Gas Production ◽  
Low Rank ◽  
Water Migration ◽  
Coal Seams ◽  
Well Pattern ◽  
Dip Angle ◽  
Desorption Model

The Baiyanghe block in Fukang, Xinjiang, China, is rich in coalbed methane (CBM) resources, and several pilot experimental wells have yielded high production. Due to the high dip angle (35–55°) of the coal seam in this area, the lack of understanding of the geological characteristics, the physical properties of coal, and gas–water migration law lead to immature development techniques and poor overall development benefits. We first conducted desorption and adsorption tests on low-rank coal of this area and found residual gas in the coal. We established a coalbed methane desorption model suitable for this area by modifying the isotherm adsorption model. Next, by analyzing the influence of the gas–water gravity differentiation in the high–dip angle coal seam and the shallow fired coalbed methane characteristics in this area, we discovered the leakage of CBM from the shallow exposed area of the coal seam. Given the particular physical property of coal and gas–water migration characteristics in this area, we optimized the well pattern: (i) the U-shaped along-dip horizontal well group in coal seams is the main production well for gas production with a spacing distance of 312 m; (ii) a multistage fracturing well drilled in the floor of coal is for water production; and (iii) vertical wells with a spacing distance of 156 m in the shallow area is to capture CBM leakage. Using numerical simulation and net present value (NPV) economics models, we optimized the well pattern details. Applying our CBM desorption model, the numerical simulator can improve the accuracy of the low-rank coalbed methane productivity forecast. The optimization results demonstrated the following: 1) the cumulative gas production of single U-shaped well increased by 89% with the optimal well spacing, 2) the cumulative gas production of the well group increased by 87.54% after adding the floor staged horizontal well, and 3) the amount of CBM leakage decrease by 67.59%.

Analysis of Critical Restricting Factors and Proposals for Coabed Methane Development in China

2011 ◽  
Vol 361-363 ◽  
pp. 848-852
Author(s):  
Jian Yun ◽  
Feng Yin Xu ◽  
Wen Ting Zeng ◽  
Ning Ning Zhong ◽  
Jia Lin Wang
Keyword(s):  
Coalbed Methane ◽  
Low Rank ◽  
Atmospheric Environment ◽  
Coal Bed ◽  
Energy Structure ◽  
Low Carbon ◽  
Geological Conditions ◽  
Well Yield ◽  
Single Well ◽  
Exploration And Development

"Clean technology and low carbon" is becoming a new trend of energy development worldwide. To speed up Coalbed Methane (CBM) exploration and development is of significant importance to reduce coal mine gas accidents, to protect atmospheric environment and to improve energy structure. Greater efforts have been exerted to CBM development, and three major CBM enterprises emerged. Qinnan, Lu’an and Sanjiao cooperation modes are developed to promote the coordinated development of gas extraction and coal mining. Many exploration and development technologies, tailored for various rank coal methane and for different geological conditions, are developed. Exploring technology, in CBM buried deeper than 800m and in low-rank coal bed methane development, has achieved substantial breakthrough. Moreover, Qinnan, Hancheng, Daning-jixian and Baode four favorable blocks are all adjacent to the major existing pipelines. China is rich in CBM resources, with great potentials and promising prospects, however, two factors of technology and management are still constraining the development of China’s CBM. Based on the analysis of the key factors, four following suggestions are proposed: to adjust strategies based on the resource distribution, to further coordinate governmental policies and entrepreneur performance, to strive to make technological breakthroughs in increasing single well yield and in promoting integrated economic efficiency, to establish a unified information platform to avoid disorderly competition and repeated investment.

Exploration Prospect of Low Rank Coalbed Methane Coal in Huhehu Depression Hailar Basin

2013 ◽  
Vol 734-737 ◽  
pp. 1196-1199 ◽  
Author(s):  
Cheng Wu Xu
Keyword(s):  
Experimental Data ◽  
Coal Seam ◽  
Coalbed Methane ◽  
Mineral Content ◽  
Low Rank ◽  
Control Factors ◽  
Hailar Basin ◽  
Target Layer ◽  
Coal Seam Thickness ◽  
Favorable Area

CBM resource in Huhehu depression Hailar Basin is large. Damoguai formaiton is the most favorable exploration coalbed methane target layer for top depth of 500-1200m, big coal seam thickness, low seam mineral content and high vitrinite by drilling, seismic and experimental data. Then cover character is evaluated and distribution is predicted. By analogy other low-level the CBM reservoir control factors, the south of depression is the most favorable area of CBM exploration for bigger coal thickness and better sealing conditions.

scholarly journals Geochemical characteristics and genesis of coalbed methane in Baode area on the eastern margin of Ordos Basin

2020 ◽  
Vol 206 ◽  
pp. 01019
Author(s):  
Weiqiang Hu ◽  
Xin Chen ◽  
Yangbing Li ◽  
Litao Ma ◽  
Wang Yuesheng ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coalbed Methane ◽  
Ordos Basin ◽  
Mean Value ◽  
Geochemical Characteristics ◽  
Coal Bed ◽  
Mass Reproduction ◽  
External Water ◽  
Systematic Understanding ◽  
Exploration And Development

The degree of coalbed methane exploration and development now in Baode area is relatively low. The lack of systematic understanding of the formation of coalbed methane in this area restricts the further exploration and development of coalbed methane. Based on the comprehensive study on the geochemical characteristics of coalbed methane components, hydrocarbon isotopes, water quality detection and hydrogen oxygen isotopes in coal seam in Baode area, the origin of coalbed methane in this area is discussed. According to the research, the hydrocarbon gas in the composition of coalbed methane in Baode area is mainly CH4 and a small amount of ethane. Both of their drying coefficients are more than 0.99, so they belong to the extremely dry coal bed methane. The value of δ13C(CH4) coalbed methane is on the low side and the value of δ13C(CO2) is on the high side, the mean value of δD(CH4) is -247.5‰, which shows the characteristics of terrestrial biogas. The water produced by coal seam is weak alkaline and belongs to the NaHCO3 type of water. which is similar to the surface water ion composition, salinity , δD(H2O) and δ18O(H2O) values, indicating that the hydrodynamic conditions of the coal seam in this area are more active. There is a recharge of external water, which is benificial to the mass reproduction of CH4 producing bacteria and the formation of biogas. In this area, the coalbed methane is a mixture of thermogenic and biological genesis, mainly composed of thermogenic gases and supplemented by biogenic gases generated through carbon dioxide reduction.

scholarly journals A fully coupled thermo-hydro-mechanical model associated with inertia and slip effects

2017 ◽  
Vol 21 (suppl. 1) ◽  
pp. 259-266 ◽  
Author(s):  
Yi Xue ◽  
Zheng-Zheng Cao ◽  
Cheng-Zheng Cai ◽  
Fa-Ning Dang ◽  
Peng Hou ◽  
...  
Keyword(s):  
Coal Seam ◽  
Mechanical Model ◽  
Coalbed Methane ◽  
Gas Flow ◽  
Gas Adsorption ◽  
Coal Bed ◽  
Klinkenberg Effect ◽  
Numerical Result ◽  
Slip Effects ◽  
Fully Coupled

The inertia and slip effects have a significant impact on the coal seam gas extraction. A fully coupled thermo-hydro-mechanical model is established in this study, which takes into account the influence of non-Darcy gas flow and Klinkenberg effect on the coal seam deformation and coalbed methane migration. The numerical result shows that the coalbed methane migration and transport evolution coal bed methane reservoir is not only dependent on the coal matrix deformation, gas pressure and gas adsorption, but also closely related to inertia effect and slip effect.

scholarly journals Analytical Model of Wellbore Stability of Fractured Coal Seam Considering the Effect of Cleat Filler and Analysis of Influencing Factors

2020 ◽  
Vol 10 (3) ◽  
pp. 1169 ◽  
Author(s):  
Xinbo Zhao ◽  
Jianjun Wang ◽  
Yue Mei
Keyword(s):  
Boundary Condition ◽  
Theoretical Model ◽  
Coal Seam ◽  
Limit Equilibrium ◽  
Wellbore Stability ◽  
Coal Bed ◽  
Affecting Factors ◽  
Stability Model ◽  
Fractured Coal ◽  
Triangular Block

Currently, coal borehole collapses frequently occur during drilling. Considering that the coal near to the wellbore is cut into blocks, and the cleat filler of the coal influences the stress distribution near the wellbore, a new theoretical solution of a near-wellbore Stress Field in coal bed wells is established. In addition, according to the limit equilibrium theory and the E.MG-C criterion, the limit sliding formula of the quadrilateral and triangular block is deduced, and the slipping direction of the blocks is further judged. Finally, the wellbore stability model of the coal seam is established. The accuracy of the theoretical model is verified through a numerical method by using the PFC software. Based upon this wellbore stability theoretical model of coal, many cleat affecting factors such as cleat spacing, cleat length, cleat angle and the cleat geometric position, are studied, and the results show that a quadrilateral block slides off more easily than a triangular block under the same boundary condition; the bigger the cleat spacing and cleat length are, the lower is the risk that blocks slide off, and increasing the cleat angle could cause blocks to slide off easily. Under the same boundary condition, whether blocks slide off or not is closely related to the well round angle.

The Influences of the Rank of Coal on Methane Sorption Capacity in Coals/Wpływ Rzędu Węgla Na Pojemność Sorpcyjną Metanu W Węglach

2014 ◽  
Vol 59 (2) ◽  
pp. 509-516
Author(s):  
Andrzej Olajossy
Keyword(s):  
Sorption Capacity ◽  
Coalbed Methane ◽  
Vitrinite Reflectance ◽  
Sorption Isotherms ◽  
Volatile Matter ◽  
Low Rank ◽  
Hard Coal ◽  
Petrographic Composition ◽  
Methane Sorption ◽  
Indian Coals

Abstract Methane sorption capacity is of significance in the issues of coalbed methane (CBM) and depends on various parameters, including mainly, on rank of coal and the maceral content in coals. However, in some of the World coals basins the influences of those parameters on methane sorption capacity is various and sometimes complicated. Usually the rank of coal is expressed by its vitrinite reflectance Ro. Moreover, in coals for which there is a high correlation between vitrinite reflectance and volatile matter Vdaf the rank of coal may also be represented by Vdaf. The influence of the rank of coal on methane sorption capacity for Polish coals is not well understood, hence the examination in the presented paper was undertaken. For the purpose of analysis there were chosen fourteen samples of hard coal originating from the Upper Silesian Basin and Lower Silesian Basin. The scope of the sorption capacity is: 15-42 cm3/g and the scope of vitrinite reflectance: 0,6-2,2%. Majority of those coals were of low rank, high volatile matter (HV), some were of middle rank, middle volatile matter (MV) and among them there was a small number of high rank, low volatile matter (LV) coals. The analysis was conducted on the basis of available from the literature results of research of petrographic composition and methane sorption isotherms. Some of those samples were in the form (shape) of grains and others - as cut out plates of coal. The high pressure isotherms previously obtained in the cited studies were analyzed here for the purpose of establishing their sorption capacity on the basis of Langmuire equation. As a result of this paper, it turned out that for low rank, HV coals the Langmuire volume VL slightly decreases with the increase of rank, reaching its minimum for the middle rank (MV) coal and then increases with the rise of the rank (LV). From the graphic illustrations presented with respect to this relation follows the similarity to the Indian coals and partially to the Australian coals.

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