scholarly journals Coalbed Methane Resources and Reservoir Characteristics of NO. II1 Coal Seam in the Jiaozuo Coalfield, China

2009 ◽  
Vol 27 (5) ◽  
pp. 307-332 ◽  
Author(s):  
Xiaodong Zhang ◽  
Yanhao Liu ◽  
Geoff Wang ◽  
Hao Liu
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Coalbed Methane ◽  
Gas Content ◽  
Burial Depth ◽  
Resource Concentration ◽  
Reservoir Evaluation ◽  
Average Value ◽  
West Part ◽  
Cbm Production

Jiaozuo coalfield is located in the northwest of Henan province, China, and close to the Southern Qinshui coal basin, the most successfully commercial CBM resource developed area in China. The No. II1 coal seam is the main economic coal seam in Jiaozuo coalfield and its average thickness exceeds 5.36m. The maximum reflectance of vitrinite (RO,max) of the No. II1 coal across the Jiaozuo is between 3.16% and 4.78%. The coalbody structure of the No. II1 coal seam changes greatly in different part and can be generally divided into 1∼3 sub-layers. The micropores in the No.II1 coal seam is the major pores, secondly are transitional pores, and then less macropores and mesopores. The No. II1 coal seam has stronger adsorption, and the reservoir natural permeability has an evident heterogeneity vary from 0.0001 to 83.71mD. High permeability region is often near fault structure or the boundary of fault block. The CBM genetic type is homologous thermal cracking gas of humic coal with high matunity. Gas content with the burial depth of 163∼1070m varies very greatly from 4.65 to 45.75m3/t, with an average value of 18.3m3/t, and gradually increases from northeast to southwest. According to the latest evaluation for CBM resource in Jiaozuo coalfield, the existing total in-place CBM resources in the No. II1 coal seam with the depth of shallower than 2000 m are close to 1.2 × 1012m3, most of them mainly distribute in the depth of 1000 ∼ 1500 m. The existing total in-place CBM resources is dominated by the inferred CBM resource reserves (more than 70%), which distribute the undrilled places with few coal geological knowledge and deeper than 1000m. The resource concentration of the No. II1 coal seam in Jiaozuo coalfield is in the range of (0.513–3.478)x108 m3/km2, with an average value of 1.805×108 m3/km2. Based on the CBM resource investigation and reservoir evaluation, the most prospective target zones for CBM production in Jiaozuo coalfield include Guhanshan coal mine, Jiulishan coal mine and the west part of Qiangnan coal district.

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.

Geological Characteristics of Coalbed Methane Reservoir in Southern Shizhuang Block, Southeastern Qinshui Basin

2013 ◽  
Vol 295-298 ◽  
pp. 3209-3212
Author(s):  
Li Ren Xing ◽  
Yan Bin Yao ◽  
Da Meng Liu ◽  
Jun Gang Liu ◽  
Lu Lu Zhou ◽  
...  
Keyword(s):  
Coal Seam ◽  
Local Structure ◽  
Coalbed Methane ◽  
Simple Structure ◽  
Gas Content ◽  
Burial Depth ◽  
Coal Seams ◽  
Structure Characteristics ◽  
Geological Characteristics ◽  
Coalbed Methane Reservoir

Southern Shizhuang Block has simple structure characteristics, relatively thick coal seams (3.1-10.5 m, 6 m in average), and favorable burial depth (450-900 m). The gas content of the No.3 coal seam in the Shanxi formation ranges from 6-20 m3/t, and it increases from the southeast to northwest area in the southern Shizhuang Block. Gas content is high in the structural low in the area, which means the gas accumulation is controlled by the geological characteristics of local structure and hydrogeologic conditions.

scholarly journals Influence of pressure, coal structure and permeability on CBM well productivity at various burial depths in South Yanchuan Block, China

2016 ◽  
Vol 20 (3) ◽  
pp. 1 ◽  
Author(s):  
Teng Li ◽  
Caifang Wu
Keyword(s):  
Effective Stress ◽  
Methane Production ◽  
Coalbed Methane ◽  
Gas Content ◽  
Burial Depth ◽  
Type I ◽  
Type Ii ◽  
Transformation Zone ◽  
Shallow Reservoir ◽  
Deep Reservoir

With a burial depth of 1000 m as the demarcation, the coal reservoir in South Yanchuan Block, China is divided into deep reservoir and shallow reservoir regions. A combination of coalbed methane well production data, well logging interpretation, coalbed methane numerical simulations and reservoir properties were used to research various production characteristics at different depths. The results indicate that coal thickness and gas content are not key factors that influence methane production. The shallow reservoir is located in a tension zone, while the deep reservoir is located in both a transformation zone and a compression zone. Although the reservoir and closure pressures increase with the burial depth, the pressures fluctuate in the deep reservoir, especially in the transformation zone. This fluctuation influences the opened degree of the fractures in the reservoir. The effective stress is lower in the deep reservoir than in the shallow reservoir, leading to higher permeability in the deep reservoir. This difference in effective stress is the key factor that influences the methane production. The combination of coal thickness and gas content also significantly influenced the methane production. Influenced by the reservoir and closure pressures, the Type III coal in the shallow reservoir is more developed, while the deep reservoir contained more developed Type I and Type II coal. The permeability increases exponentially with increasing thickness of Type I and Type II coal, which determines the high reservoir permeability in the deep reservoir. The development of Type III coal leads to the poor reservoir hydraulic fracturing effect. However, a reservoir with thick Type I and Type II coal can have a positive effect. Influencia de la presión, la estructura del carbón y su permeabilidad sobre la productividad de gas metano de carbón en profundidades de enterramiento del bloque Yanchuan Sur, ChinaResumenCon una profundidad de enterramiento de 1000 metros, el yacimiento de carbón del bloque Yanchuan Sur, en China, se divide en dos: el depósito profundo y el depósito superficial. Este trabajo combina los datos de la información de producción de gas metano asociado carbón, la interpretación de registros de pozo, las simulaciones numéricas de metano asociado a carbón y las propiedades del reservorio para encontrar las características de producción a diferentes profundidades. Los resultados indican que el espesor del carbón y el contenido de gas no son factores que alcancen a influir en la producción de metano. El depósito superficial se encuentra en una zona de tensión, mientras el depósito profundo está ubicado en una región tanto de transformación como de compresión. Aunque el reservorio y la presión de cierre se incrementan con la profundidad de enterramiento, las presiones fluctúan en el depósito profundo, especialmente en la zona de transformación. Esta fluctuación influye en el grado de apertura de las fracturas en el depósito. La tensión efectiva es más baja en el depósito profundo, lo que significa una mayor permeabilidad. La diferencia en la tensión efectiva es el factor clave que incide en la producción de metano. Afectado por las presiones de cierre y del yacimiento, el carbón tipo III en el depósito superficial está más desarrollado, mientras que el depósito profundo contiene carbón tipo I y tipo II más desarrollado. La permeabilidad se incrementa exponencialmente con el incremento del espesor en el carbón tipo I y tipo II, lo que determina la alta porosidad en el depósito profundo. El desarrollo de carbón tipo III lleva a un pobre efecto de la fractura hidráulica en el depósito. Sin embargo, un depósito con carbón tipo I y tipo II espeso podría tener un efecto positivo.

scholarly journals Study on Reservoir Properties and Critical Depth in Deep Coal Seams in Qinshui Basin, China

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Guiqiang Zheng ◽  
Bin Sun ◽  
Dawei Lv ◽  
Zhejun Pan ◽  
Huiqing Lian
Keyword(s):  
Coal Seam ◽  
Step Change ◽  
Gas Content ◽  
Burial Depth ◽  
Critical Depth ◽  
Coal Seams ◽  
Reservoir Properties ◽  
Qinshui Basin ◽  
Geological Conditions ◽  
Change Characteristics

Coalbed methane (CBM) reservoir properties and relationship of properties with burial depth were studied based on the data derived from 204 deep CBM production wells in Qinshui Basin, China. Through the study, it is found that permeability and porosity decrease with the increase of burial depth and the decreasing trend shows step-change characteristics at a critical burial depth. They also show divisional characteristics at certain burial depth. Gas content, geostress, and geotemperature increase with the increase of burial depth, and the increasing trend shows step-change characteristics and also have divisional characteristics at certain burial depth. Based on the previous study on the reservoir property changes with burial depth, three series of critical depth using different parameters are obtained through simulating the critical depth using the BP neural network method. It is found that the critical depth is different when using different parameters. Combined the previous study with the normalization of three different parameter types, the critical depth in Qinshui Basin was defined as shallow coal seam is lower than 650 m and transition band is 650–1000 m, while deep coal seam is deeper than 1000 m. In deep coal seams, the geological conditions and recovery becomes poor, so it can be defined as unfavorable zones. Therefore, other development means, for example, CO2 injection, need to be used to accelerate the deep coal methane development.

scholarly journals CBM Resources Estimations for the Development of Coal Mine Methane in the Asturian Central Basin, Spain

Proceedings ◽  
2018 ◽  
Vol 2 (23) ◽  
pp. 1404
Author(s):  
Pablo Cienfuegos-Suárez ◽  
Efrén García-Ordiales ◽  
Diego Alonso-Fernández ◽  
Jorge Enrique Soto-Yen
Keyword(s):  
Coal Mine ◽  
Coalbed Methane ◽  
Technological Development ◽  
Gas Content ◽  
Central Basin ◽  
Economic Interest ◽  
Coal Seams ◽  
Coal Basin ◽  
Coal Mine Methane ◽  
Made In

New technological development and a best knowledge of the basin allow to have justified expectation to find coalbed methane reserves. Measurements of gas content in unexploited coal seams are made in order to estimate the CBM could revive the economic interest of the Asturian Central Coal Basin (ACCB). According to first estimations based on the studies accomplished, the minimum resources of coalbed methane in the whole of the Asturian Central Coal Basin are in the order of 25,000 Mm3 and the gas content of the coal seams range from 6 m3 to 14 m3/t. The introduction should briefly place the study in a broad context and define the purpose of the work and its significance.

Reasons and Control Countermeasures of Special Soft Coal Roadway Deformation in Liangbei Coal Mine

2013 ◽  
Vol 671-674 ◽  
pp. 1144-1149
Author(s):  
Le Tuan Cheng ◽  
Jia Lin Zhang ◽  
Zheng Sheng Zou ◽  
Qing Bo Li
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Mining Area ◽  
Gas Content ◽  
Deformation And Failure ◽  
Gas Outburst ◽  
Soft Coal ◽  
Coal Roadway ◽  
Roadway Stability ◽  
Roadway Deformation

B1 coal seam located at -550m level in Liangbei Coal Mine is a typical "three-soft" seam. The coal roadway with a depth of 610-750m lies under the critical softening depth of the roadway, and its support difficulty coefficient is 1.5-2.0. The coal has poor air permeability, high gas content and high gas pressure, so danger degree of the gas outburst is relatively strong. The coal seam was destroyed in a disastrous state by more than 100 boreholes for gas outburst prevention during the excavation. This results in the difficulty in the roadway support. Engineering geological characteristics of the coal roadway at 11 mining area are introduced. Based on the engineering geo-mechanics method, the reasons of deformation and failure of the coal roadway are analyzed. In view of problems in excavation and support, as well as the type of the coal roadway deformation mechanism, the borehole parameters are optimized for the gas outburst prevention, and bolt-net-cable coupling support with high convex steel-belt is used to control the coal roadway stability at 11 mining area. Practice shows that the effect is fine.

Prediction Technology of Coal and Gas Outburst in Xuandong Coal Mine

2011 ◽  
Vol 255-260 ◽  
pp. 3731-3734
Author(s):  
Sheng Shan Zhao ◽  
Wei Dong Pan ◽  
Xin Wang ◽  
Jia Dun Liu
Keyword(s):  
Coal Mine ◽  
Magmatic Rock ◽  
Coal And Gas Outburst ◽  
Gas Content ◽  
Burial Depth ◽  
Disaster Reduction ◽  
Geological Structures ◽  
Practical Situation ◽  
Gas Outburst ◽  
Geological Conditions

Based on the complicated geological conditions of coal seam in Xuandong Coal Mine, such as deep burial depth, high gas content, magmatic rock intrusion and so on, the distribution regularities of magmatic rock, gas and geological structures were analyzed and studied. Combining with the practical situation of the dynamic disaster and phenomenon during the mining, the dangerous zones of coal and gas outburst were predicted and regional divided. The research results would have certain significance of practical guide to the outburst prevention and disaster reduction.

scholarly journals Multi-factor controls on initial gas production pressure of coalbed methane wells in Changzhi-Anze block, Central-Southern of Qinshui Basin, China

2020 ◽  
Vol 38 (1-2) ◽  
pp. 3-23 ◽  
Author(s):  
Yang Zhao ◽  
Xiaodong Zhang ◽  
Shuo Zhang ◽  
Jiaosheng Yang ◽  
Xianzhong Li ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Gas Production ◽  
Gas Content ◽  
Working Fluid ◽  
Water Yield ◽  
Burial Depth ◽  
Reservoir Pressure ◽  
Pressure Drops ◽  
Factors Affecting ◽  
Control Factors

Adsorption and desorption of coalbed methane are generally at a dynamic equilibrium state under the undisturbed coal reservoir. However, as the reservoir pressure drops to a certain value during the extraction of coalbed methane, the equilibrium state is destroyed and thus more coalbed methane desorbs and escapes from coal to wellbore. Here the corresponding bottom-hole fluid pressure is called initial gas production pressure (IGPP) in the development practice of coalbed methane wells. This paper, which has taken Changzhi-Anze block in the central-southern part of Qinshui basin as the study object, addresses the distribution characteristic and control factors of IGPP of coalbed methane wells and then explores the key factors affecting IGPP using grey correlation analysis theory. The results indicate that IGPP varies from 1.09 MPa to 6.57 MPa, showing a distribution law with high in the middle and low in the west and east of the study area, which presents a similar distribution characteristic with burial depth, thickness, coal rank, gas content, original reservoir pressure, and in-situ stress. Further, through grey correlation analysis, it concludes that the correlation degrees of control factors affecting IGPP of coalbed methane wells in the descending order are decline rate of working fluid level, water yield before gas production, reservoir pressure, coal thickness, coal rank, minimum horizontal principal stress, burial depth, and gas content. Among these factors, engineering factors, including decline rate of working fluid level and water yield before gas production, present a key controlling effect, because they can determine the smooth migration pathway directly during initial water production. And another key factor, original reservoir pressure also builds strong and positive correlation with IGPP under the interaction of other geology and reservoir factors, revealing the capability of gas desorption and the transmission of pressure drops.

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.

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.

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