Geological factors on gas entrapment mechanism and prediction of coalbed methane of the no. 6 coal seam in the Jungar coalfield, northeast Ordos Basin, China

2014 ◽  
Vol 8 (4) ◽  
pp. 449 ◽  
Author(s):  
Yongkai Qiu ◽  
Dameng Liu ◽  
Derek Elsworth ◽  
Yanbin Yao ◽  
Yidong Cai ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coalbed Methane ◽  
Ordos Basin ◽  
Geological Factors ◽  
Gas Entrapment ◽  
Jungar Coalfield

scholarly journals Geological conditions of coalbed methane accumulation in the Hancheng area, southeastern Ordos Basin, China: Implications for coalbed methane high-yield potential

2019 ◽  
Vol 37 (3) ◽  
pp. 922-944 ◽  
Author(s):  
Chen Guo ◽  
Yucheng Xia ◽  
Dongmin Ma ◽  
Xueyang Sun ◽  
Gelian Dai ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coalbed Methane ◽  
Hot Spot ◽  
Ordos Basin ◽  
Yield Potential ◽  
High Yield ◽  
Tectonic Deformation ◽  
Critical Depth ◽  
Geological Conditions ◽  
High Yield Potential

The Hancheng area is a hot spot for coalbed methane exploration and exploitation in China. Structure is a key factor affecting coalbed methane accumulation and production in the Hancheng area. For a better understanding of the coalbed methane accumulation conditions and high-yield potential, this study investigates the structural patterns and evolution, the hydrogeological conditions, and the geothermal field in the coal-bearing strata in the Hancheng area. Then, the spatial distribution of the coalbed methane content and the tectonic deformation of the coal seam are evaluated. Finally, the critical depth for coalbed methane enrichment and a high-yield potential are revealed, and the favorable areas for coalbed methane development are predicted. The following conclusions are obtained: (1) Under the Yanshanian SE–NW trending maximum principle stress, the Hancheng overturned anticline was formed and subsequently subjected to uplift and erosion along its axis, which led to the NW limb of the anticline forming the current uniclinal structure of the Hancheng area; (2) Four degrees of tectonic deformation in the coal seam are identified based on structural curvature analysis. The moderately deformed area shallower than 800 m would benefit coalbed methane production with higher permeability. Most of the locations of coal and gas outburst events that occur during coal mining were distributed along the highly and very highly deformed areas; (3) The gas content gradually increases along the NW-trending inclination of the coal seam. 400 m and 800 m are discriminated as the critical depth levels for controlling coalbed methane accumulation and a high yield. Secondary biogenic methane was generated in the shallow formations; and (4) The Hancheng area is divided into four ranks for determining coalbed methane development potential. From high to low, they are ranked A, B-1, B-2, and C. Most of the high-yield wells are located in the areas ranked A and B-1.

Analysis of Distribution of Coalbed Methane and Geological Controlling Factors in Huanghebei Mining Area

2013 ◽  
Vol 448-453 ◽  
pp. 3757-3761
Author(s):  
Yan Ru Meng ◽  
Zeng Xue Li ◽  
Hai Yan Liu ◽  
Nan Jiang ◽  
Juan Liu
Keyword(s):  
Coal Seam ◽  
Coalbed Methane ◽  
Mining Area ◽  
Controlling Factors ◽  
Methane Content ◽  
Burial Depth ◽  
Distribution Characteristics ◽  
Deep Well ◽  
Hydrogeological Conditions ◽  
Geological Factors

Distribution characteristics of coalbed methane in Huanghebei mining area were studied and influence of geological factors such as faults, lithology of coal seam roof and floor, magmatic activities, burial depth and upper bedrock thickness of coal seam and hydrogeological conditions on occurrence of coalbed methane were deeply discussed in this paper. Coalbed methane content of mining area increased gradually from southeast to northwest. Coalbed methane in deep well points of mining area is dominated by methane and that in shallow parts contained higher content of nitrogen.

scholarly journals Productivity subarea of CBM field and its key controlling factors: A case study in the Hancheng pilot test area, southeastern Ordos Basin, China

2018 ◽  
Vol 37 (1) ◽  
pp. 102-124 ◽  
Author(s):  
Yanfei Liu ◽  
Dazhen Tang ◽  
Song Li ◽  
Hao Xu ◽  
Shu Tao ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Ordos Basin ◽  
Gas Production ◽  
Test Area ◽  
Gas Content ◽  
Pilot Test ◽  
Coal Seams ◽  
Geological Factors ◽  
Drop Rate

The Hancheng block in the southeastern Ordos Basin is one of the earliest and the most important areas for coalbed methane exploration and development in China. However, there are significant production variations in different wells or even some adjacent wells in the Hancheng block. To reveal the reasons of production differences in such a small scale, further detailed studies of coalbed methane productivity in the Hancheng pilot test area, a precursor trial area in Hancheng block with mature, well-characterized coalbed methane reservoirs and long-term production database, were conducted. The influence of nine factors (including engineering and geological factors) on gas production was analyzed. By introducing the rough set theory, which is applicable to the vague, imprecise, and incomplete information system, this paper presents a method for quantitative evaluation of the influencing factors on gas production. The results indicate that there are certain distribution characteristics of productivity in Hancheng pilot test area, which can be partitioned into four zones. The degressive order of the influencing degree of these nine factors is (i) the distance between the well and the fault, (ii) the structure curvature of the coal seams, (iii) the gas content, (iv) the critical reservoir ratio, (v) the volume of the fracturing liquids per meter, (vi) the volume of the fracturing sand per meter, (vii) the dynamic liquid level drop rate, (viii) the depth, and (ix) the thickness. Geological factors, especially the influence of fault, structural curvature of the coal seams and gas content, play a major role in controlling long-term gas production. Engineering factors (effect of fracturing and dynamic liquid level drop rate) have always been integral parts of coalbed methane development.

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 Prediction of high-quality coalbed methane reservoirs based on the fuzzy gray model: An investigation into coal seam No. 8 in Gujiao, Xishan, North China

2020 ◽  
Vol 38 (4) ◽  
pp. 1054-1081
Author(s):  
Huang Bo ◽  
Qin Yong ◽  
Wanhong Zhang ◽  
Qiming Zheng ◽  
Songlin Shi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Coal Seam ◽  
Coalbed Methane ◽  
Low Permeability ◽  
Gray Model ◽  
High Quality ◽  
The North ◽  
Reservoir Permeability ◽  
Geological Factors ◽  
Coalbed Methane Production

Coalbed methane (CBM) resources are abundant in the Gujiao block, Xishan coalfield, China. However, few studies have been conducted on the coalbed methane geology of the Gujiao block. In the present study, based on logging responses and numerical simulations, the coal structures of coal seam No. 8 of this block were identified, and the mechanical properties of the coal and its roof/floor were calculated. The geological factors influencing the coalbed methane reservoir were quantitatively characterized according to the fuzzy gray model. High-quality coalbed methane reservoirs in the No. 8 coal were predicted and classified using the model, and some suggestions on rational exploitation were determined. Reservoirs of the No. 8 coal are dominated by the III-type, followed by the II- and IV-types. The III-type reservoirs are the most common, and primarily developed at the Xiqu, Zhenchengdi, Malan, and Tunlan coal mines in the north of the studied area. The III-type reservoirs represent low coalbed methane contents, high thickness proportions of granulated-mylonitized coal, and low burial depths. The II-type reservoirs are primarily developed close to the axis of the Malan syncline and in the south and northwest of the studied area, and have low permeability, less significant differences between the mechanical properties of coals and their roofs and floors, and low reservoir pressure gradients. The IV-type reservoirs have a scattered development, dominance of granulated-mylonitized coal, and low permeability, indicating low potential to improve reservoir permeability. Targeted exploitation technology and drainage systems corresponding to the different types of coal reservoirs should be proposed to improve coalbed methane production.

scholarly journals Quantify Coal Macrolithotypes of a Whole Coal Seam: A Method Combing Multiple Geophysical Logging and Principal Component Analysis

Energies ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 213
Author(s):  
Chao Cui ◽  
Suoliang Chang ◽  
Yanbin Yao ◽  
Lutong Cao
Keyword(s):  
Principal Component Analysis ◽  
Coal Seam ◽  
Coalbed Methane ◽  
Principal Component ◽  
Component Analysis ◽  
Gas Production ◽  
Index Model ◽  
Geophysical Logging ◽  
The Relationship ◽  
Observation Results

Coal macrolithotypes control the reservoir heterogeneity, which plays a significant role in the exploration and development of coalbed methane. Traditional methods for coal macrolithotype evaluation often rely on core observation, but these techniques are non-economical and insufficient. The geophysical logging data are easily available for coalbed methane exploration; thus, it is necessary to find a relationship between core observation results and wireline logging data, and then to provide a new method to quantify coal macrolithotypes of a whole coal seam. In this study, we propose a L-Index model by combing the multiple geophysical logging data with principal component analysis, and we use the L-Index model to quantitatively evaluate the vertical and regional distributions of the macrolithotypes of No. 3 coal seam in Zhengzhuang field, southern Qinshui basin. Moreover, we also proposed a S-Index model to quantitatively evaluate the general brightness of a whole coal seam: the increase of the S-Index from 1 to 3.7, indicates decreasing brightness, i.e., from bright coal to dull coal. Finally, we discussed the relationship between S-Index and the hydro-fracturing effect. It was found that the coal seam with low S-Index values can easily form long extending fractures during hydraulic fracturing. Therefore, the lower S-Index values indicate much more favorable gas production potential in the Zhengzhuang field. This study provides a new methodology to evaluate coal macrolithotypes by using geophysical logging data.

scholarly journals Classification of coal seam outburst hazards and evaluation of the importance of influencing factors

2017 ◽  
Vol 9 (1) ◽  
Author(s):  
Xianzhi Shi ◽  
Dazhao Song ◽  
Ziwei Qian
Keyword(s):  
Coal Seam ◽  
Multivariate Regression ◽  
Multivariate Regression Analysis ◽  
Scientific Basis ◽  
Prevention Measures ◽  
Coal Seam Gas ◽  
Geological Factors ◽  
Hazard Level ◽  
Outburst Hazard

AbstractCoal and gas outbursts are the result of several geological factors related to coal seam gas (coal seam gas pressureTo classify the outburst hazard level of a coal seam by means of statistical methods, this study considered the geological parameters of coal seam gas and statistical data on the amount of material involved in coal outbursts. Through multivariate regression analysis, a multivariate regression equation between the outburst coal quantity andUsing a significance evaluation of the aforementioned factors, the relative contributions of the gas-related geological parameters to the outburst hazard level of a coal seam were found to follow the orderThis work provides a scientific basis for evaluating the outburst hazard level of a coal seam and adopting feasible and economical outburst-prevention measures.

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