Based on analysis of a large data set and supplementary sampling and analysis for hazardous trace elements in coal samples from the Huainan Coalfield,a generalized contrast-weighted scale index method was used to esta...Based on analysis of a large data set and supplementary sampling and analysis for hazardous trace elements in coal samples from the Huainan Coalfield,a generalized contrast-weighted scale index method was used to establish a model to evaluate the grade of coal cleanliness and its regional distribution in the main coal seam(No.13-1)The results showed that:(1)The contents of Cr,Mn and Ni in the coal seam are relatively high and the average values are greater than 20μg/g.The contents of Se and Hg are at a high level while most other trace elements are at normal levels.(2)The cleanliness grade of the coal seam is mainly grade III-IV,which corresponds to a relatively good-medium coal cleanliness grade.However,some parts of the seam are at grade V(relatively poor coal cleanliness).(3)Coal of relatively good cleanliness grade(grade III)is distributed mainly in the regions corresponding to the Zhuji-Dingji-Gubei coal mines and in the eastern periphery of the Panji coal mine.Coal of medium cleanliness(grade IV)is distributed mainly in the regions of the Panji-Xiejiaji and Kouzidong coalmines.Relatively poor grade coal(grade V)is distributed in the southwest regions of the coalfield and the contents of Cr,As and Hg in coal collected from the relatively poor coal cleanliness regions often exceed the regulatory standards for the maximum concentration limits.展开更多
HN-1#is the first fully working coring well of the Taiyuan Formation(Ty)in the Huinan Coalfield and exploration studies are currently underway on the associated resources of the coal-bearing strata.The HN-1#well is lo...HN-1#is the first fully working coring well of the Taiyuan Formation(Ty)in the Huinan Coalfield and exploration studies are currently underway on the associated resources of the coal-bearing strata.The HN-1#well is located in the Fufeng thrust nappe structural belt in the south of the Huainan Coalfield.Three coal samples from the Ty were collected from HN-1#and inductively-coupled plasma mass spectrometry and inductively-coupled plasma atomic emission spectrometry were used to determine the Ge content of each sample.Based on proximate and ultimate analyses,microscopy data,and analyses of the ash products,some important findings were made.The Ty coal samples had a relatively high total sulfur(Sud)content(4.24%),thus the coal was considered to be a lower ranked coal(high volatility bituminous coal),which also had a low coal ash composition index(k,1.87).Collodetrinite was the main submaceral of the Ty coal.Small amounts of pyrite particles were found in the coal seams of the Ty,while the contents of pyrite and algae in the top and bottom sections of the coal seam were relatively high,which meant that the swampy peat conditions which existed during the formation of the coal seams were affected by seawater;also the degree of mineralization of the coal seam was relatively high,which is consistent with reducing conditions in a coastal environment setting.Atomic force microscopy(AFM)experiments showed that the modes of occurrence of Ge in the Ty coal were mainly those for organic-bound and adsorbed Ge species.The organic carbon isotope values for the Ty coal ranged from-24.1‰to-23.8‰,with an average value of-24.0‰,which is equivalent to the value for terrestrial plants(average value-24.0‰).The Ge content of the Ty coal was 13.57 mg/kg.The Ge content was negatively correlated with volatile matter and the ash yield.展开更多
Coalbed methane (CBM) is a kind of burgeoning and enormously potential clean energy resource, and the temperature of the thermogenic CBM generation is close to that of the partial annealing zone (PAZ) of apatite fissi...Coalbed methane (CBM) is a kind of burgeoning and enormously potential clean energy resource, and the temperature of the thermogenic CBM generation is close to that of the partial annealing zone (PAZ) of apatite fission tracks (AFT). In this study the thermo-tectonic history of the Huainan Coalfield and the potential CBM resource were studied and discussed by using the AFT method. The AFT data indicate that the apparent ages of AFT vary from 45.5 to 199.1 Ma. They are younger than the ages of their host strata (255–1800 Ma) except one sample, and the single-grain ages of AFT can be classified as a single age group for each sample. In combination with the geological setting, modeling results of the AFT ages, average lengths, and the thermal history based on the AFT single-grain ages and length distributions, some preliminary conclusions can be drawn as follows: (1) at least three thermo-tectonic events (in the periods of ～240, 140 and 80 Ma, respectively) have occurred in the study area since the Late Paleozoic. The occurrence of both the first (during 240–220 Ma) and second (during 160–120 Ma) thermo-tectonic events is possibly responsible for the establishment of the patterns of gas generation and reservoir formation. The second thermo-tectonic event also led to slight accumulation of hydrocarbons and generation of thermogenic gas; (2) the AFT ages of most coal-bearing strata lie between 50 and 70 Ma. They should represent the cooling ages and the ages of inferred uplift and denudation, as well as the possible CBM release history. Therefore, the maximum burial depth of coal-bearing strata and the denudation thickness of the overlying strata are over 3000 and 2000 m in the Upper Cretaceous and Paleogene series, respectively; and (3) subsequently, a spot of secondary biogenic and scarcely thermogenic gas generation occurred due to negligible sedimentation during the Neogene and Quaternary periods. Thus, it can be presumed that subsequent tectonism would destroy the CBM reservoir after its formation in the Huainan Coalfield, especially in its structural development region. These AFT data may be helpful for a better understanding of the thermo-tectonic history of the Huainan Coalfield, as well as of CBM generation, storage and release in the Huainan Coalfield.展开更多
The geothermal history and the tectonic subsidence history of the Huaibei-Huainan coalfields were reconstructed by using the vitrinite reflectance data, and their correlative restriction on coalbed gas generation of H...The geothermal history and the tectonic subsidence history of the Huaibei-Huainan coalfields were reconstructed by using the vitrinite reflectance data, and their correlative restriction on coalbed gas generation of Huaibei-Huainan coalfields and Qinshui coal basin was discussed. The burial, thermal, and maturity histories of are similar between Huaibei coalfield and Huainan coalfield, obviously different from those of Qinshui coal basin. Based on the tectono-thermal evolution characters of Huaibei-Huainan coalfields and Qinshui basin, the process of coalbed gas generation can be divided into three stages： （1） Dur- ing Early Mesozoic, both in Huaibei-Huainan and Qinshui, the buried depth of Permian coal seams increased rapidly, which resulted in strong metamorphism and high burial temperature of coal seams. At this stage, the coal rank was mainly fat coal, and locally reached coking coal. These created an environment favoring the generation of thermogenic gas. （2） From Late Ju- rassic to Cretaceous, in the areas of Huaibei-Hualnan, the strata suffered from erosion and the crust became thinning, and the Permian coal-bearing strata were uplifted to surface. At this stage, the thermogenic gas mostly escaped. Conversely, in Qinshui basin, the cover strata of coal seams kept intact during this stage, and the thermogenic gas were mostly preserved. Furthermore, with the interaction of magmatism, the burial temperature of coal seams reached higher peak value, and it was suitable for the secondary generation of thermogenic gas. （3） From Paleogene onward, in area of Huainan-Huaibei, the maturity of coal and burial temperature were propitious to the generation of secondary biogenic gases. However, in Qinshui basin, the maturity of coal went against genesis of second biogenic gas or thermogenic gas. By comparison, Huaibei-Huainan coalfields are dominated by thermogenic gas with a significant biogenic gas and hydrodynamic overprint, whereas Qinshui basin is dominated mainly by thermogenic gas.展开更多
The secondary biogenic gas is an important original type of the coalbed methane (CBM) in China. Based on the analyses of sedimentary and burial history of the Permian coal-bearing strata, combined with thermal history...The secondary biogenic gas is an important original type of the coalbed methane (CBM) in China. Based on the analyses of sedimentary and burial history of the Permian coal-bearing strata, combined with thermal history and gas generation process of coals, the CBM reservoir-forming dynamic system with mixed secondary biogenic and thermogenic gases in the Huainan Coalfield is subdivided into four evolutionary stages as follows: (i) shallowly-buried peat and early biogenic gas stage; (ii) deeply buried coal seams and thermogenic gas stage; (iii) exhumation of coal-bearing strata and adsorbed gas lost stage; and (iv) re-buried coal-bearing strata and secondary biogenic gas supplement stage. The Huainan CBM reservoir-forming model has the features of the basin-centered gas accumulation. The evolution of the reservoir-forming dynamic system proves that the thermogenic gas is not the main gas source for the Huainan CBM reservoir. Only the secondary biogenic gases as an additional source replenish into the coal bed after basin-uplift, erosional unroofing and subsequent scattering of thermogenic gases. Then this kind of mixed CBM reservoirs can be formed under suitable conditions.展开更多
The coalbed methane (CBM) reservoir is the basic geological unit of CBM storing and CBM resource developing. The forming conditions of the CBM reservoir include coal thickness, coal rank, seam buried depth, caprock, a...The coalbed methane (CBM) reservoir is the basic geological unit of CBM storing and CBM resource developing. The forming conditions of the CBM reservoir include coal thickness, coal rank, seam buried depth, caprock, and geological structure. The division of a CBM reservoir in the Huainan coalfield is mainly based on the geological structure form and seam buried depth. According to the Fufeng nappe and the secondary structures of Huainan syn-clinorium, seven CBM reservoirs are divided in the Huainan Coalfield, such as Caijiagang, and the dynamic mechanism of CBM forming is analyzed. The structural position where the CBM reservoir is located has the important controlling role on the features of CBM reservoir.展开更多
基金the Key Research and Development Projects in Anhui Province(201904a07020071)the Science and Technology Project of the Department of Land and Resources of Anhui Province(2016-K-16)the Key Research and Development Projects in Anhui Province(1804a0802198).
文摘Based on analysis of a large data set and supplementary sampling and analysis for hazardous trace elements in coal samples from the Huainan Coalfield,a generalized contrast-weighted scale index method was used to establish a model to evaluate the grade of coal cleanliness and its regional distribution in the main coal seam(No.13-1)The results showed that:(1)The contents of Cr,Mn and Ni in the coal seam are relatively high and the average values are greater than 20μg/g.The contents of Se and Hg are at a high level while most other trace elements are at normal levels.(2)The cleanliness grade of the coal seam is mainly grade III-IV,which corresponds to a relatively good-medium coal cleanliness grade.However,some parts of the seam are at grade V(relatively poor coal cleanliness).(3)Coal of relatively good cleanliness grade(grade III)is distributed mainly in the regions corresponding to the Zhuji-Dingji-Gubei coal mines and in the eastern periphery of the Panji coal mine.Coal of medium cleanliness(grade IV)is distributed mainly in the regions of the Panji-Xiejiaji and Kouzidong coalmines.Relatively poor grade coal(grade V)is distributed in the southwest regions of the coalfield and the contents of Cr,As and Hg in coal collected from the relatively poor coal cleanliness regions often exceed the regulatory standards for the maximum concentration limits.
基金the Public Welfare Geological Work Project of Anhui Province(2016-g-3-33)National Natural Science Foundation of China(No.41502152)the Anhui Postdoctoral Science Foundation(2015M571940).
文摘HN-1#is the first fully working coring well of the Taiyuan Formation(Ty)in the Huinan Coalfield and exploration studies are currently underway on the associated resources of the coal-bearing strata.The HN-1#well is located in the Fufeng thrust nappe structural belt in the south of the Huainan Coalfield.Three coal samples from the Ty were collected from HN-1#and inductively-coupled plasma mass spectrometry and inductively-coupled plasma atomic emission spectrometry were used to determine the Ge content of each sample.Based on proximate and ultimate analyses,microscopy data,and analyses of the ash products,some important findings were made.The Ty coal samples had a relatively high total sulfur(Sud)content(4.24%),thus the coal was considered to be a lower ranked coal(high volatility bituminous coal),which also had a low coal ash composition index(k,1.87).Collodetrinite was the main submaceral of the Ty coal.Small amounts of pyrite particles were found in the coal seams of the Ty,while the contents of pyrite and algae in the top and bottom sections of the coal seam were relatively high,which meant that the swampy peat conditions which existed during the formation of the coal seams were affected by seawater;also the degree of mineralization of the coal seam was relatively high,which is consistent with reducing conditions in a coastal environment setting.Atomic force microscopy(AFM)experiments showed that the modes of occurrence of Ge in the Ty coal were mainly those for organic-bound and adsorbed Ge species.The organic carbon isotope values for the Ty coal ranged from-24.1‰to-23.8‰,with an average value of-24.0‰,which is equivalent to the value for terrestrial plants(average value-24.0‰).The Ge content of the Ty coal was 13.57 mg/kg.The Ge content was negatively correlated with volatile matter and the ash yield.
基金supported by the National Natural Science Foundation of China (Grant No 40572124)
文摘Coalbed methane (CBM) is a kind of burgeoning and enormously potential clean energy resource, and the temperature of the thermogenic CBM generation is close to that of the partial annealing zone (PAZ) of apatite fission tracks (AFT). In this study the thermo-tectonic history of the Huainan Coalfield and the potential CBM resource were studied and discussed by using the AFT method. The AFT data indicate that the apparent ages of AFT vary from 45.5 to 199.1 Ma. They are younger than the ages of their host strata (255–1800 Ma) except one sample, and the single-grain ages of AFT can be classified as a single age group for each sample. In combination with the geological setting, modeling results of the AFT ages, average lengths, and the thermal history based on the AFT single-grain ages and length distributions, some preliminary conclusions can be drawn as follows: (1) at least three thermo-tectonic events (in the periods of ～240, 140 and 80 Ma, respectively) have occurred in the study area since the Late Paleozoic. The occurrence of both the first (during 240–220 Ma) and second (during 160–120 Ma) thermo-tectonic events is possibly responsible for the establishment of the patterns of gas generation and reservoir formation. The second thermo-tectonic event also led to slight accumulation of hydrocarbons and generation of thermogenic gas; (2) the AFT ages of most coal-bearing strata lie between 50 and 70 Ma. They should represent the cooling ages and the ages of inferred uplift and denudation, as well as the possible CBM release history. Therefore, the maximum burial depth of coal-bearing strata and the denudation thickness of the overlying strata are over 3000 and 2000 m in the Upper Cretaceous and Paleogene series, respectively; and (3) subsequently, a spot of secondary biogenic and scarcely thermogenic gas generation occurred due to negligible sedimentation during the Neogene and Quaternary periods. Thus, it can be presumed that subsequent tectonism would destroy the CBM reservoir after its formation in the Huainan Coalfield, especially in its structural development region. These AFT data may be helpful for a better understanding of the thermo-tectonic history of the Huainan Coalfield, as well as of CBM generation, storage and release in the Huainan Coalfield.
基金supported by National Natural Science Foundation of China (Grant Nos. 41030422, 40772135, 40972131, 40940014)National Basic Research Program of China (Grant No. 2009CB219601)
文摘The geothermal history and the tectonic subsidence history of the Huaibei-Huainan coalfields were reconstructed by using the vitrinite reflectance data, and their correlative restriction on coalbed gas generation of Huaibei-Huainan coalfields and Qinshui coal basin was discussed. The burial, thermal, and maturity histories of are similar between Huaibei coalfield and Huainan coalfield, obviously different from those of Qinshui coal basin. Based on the tectono-thermal evolution characters of Huaibei-Huainan coalfields and Qinshui basin, the process of coalbed gas generation can be divided into three stages： （1） Dur- ing Early Mesozoic, both in Huaibei-Huainan and Qinshui, the buried depth of Permian coal seams increased rapidly, which resulted in strong metamorphism and high burial temperature of coal seams. At this stage, the coal rank was mainly fat coal, and locally reached coking coal. These created an environment favoring the generation of thermogenic gas. （2） From Late Ju- rassic to Cretaceous, in the areas of Huaibei-Hualnan, the strata suffered from erosion and the crust became thinning, and the Permian coal-bearing strata were uplifted to surface. At this stage, the thermogenic gas mostly escaped. Conversely, in Qinshui basin, the cover strata of coal seams kept intact during this stage, and the thermogenic gas were mostly preserved. Furthermore, with the interaction of magmatism, the burial temperature of coal seams reached higher peak value, and it was suitable for the secondary generation of thermogenic gas. （3） From Paleogene onward, in area of Huainan-Huaibei, the maturity of coal and burial temperature were propitious to the generation of secondary biogenic gases. However, in Qinshui basin, the maturity of coal went against genesis of second biogenic gas or thermogenic gas. By comparison, Huaibei-Huainan coalfields are dominated by thermogenic gas with a significant biogenic gas and hydrodynamic overprint, whereas Qinshui basin is dominated mainly by thermogenic gas.
文摘The secondary biogenic gas is an important original type of the coalbed methane (CBM) in China. Based on the analyses of sedimentary and burial history of the Permian coal-bearing strata, combined with thermal history and gas generation process of coals, the CBM reservoir-forming dynamic system with mixed secondary biogenic and thermogenic gases in the Huainan Coalfield is subdivided into four evolutionary stages as follows: (i) shallowly-buried peat and early biogenic gas stage; (ii) deeply buried coal seams and thermogenic gas stage; (iii) exhumation of coal-bearing strata and adsorbed gas lost stage; and (iv) re-buried coal-bearing strata and secondary biogenic gas supplement stage. The Huainan CBM reservoir-forming model has the features of the basin-centered gas accumulation. The evolution of the reservoir-forming dynamic system proves that the thermogenic gas is not the main gas source for the Huainan CBM reservoir. Only the secondary biogenic gases as an additional source replenish into the coal bed after basin-uplift, erosional unroofing and subsequent scattering of thermogenic gases. Then this kind of mixed CBM reservoirs can be formed under suitable conditions.
文摘The coalbed methane (CBM) reservoir is the basic geological unit of CBM storing and CBM resource developing. The forming conditions of the CBM reservoir include coal thickness, coal rank, seam buried depth, caprock, and geological structure. The division of a CBM reservoir in the Huainan coalfield is mainly based on the geological structure form and seam buried depth. According to the Fufeng nappe and the secondary structures of Huainan syn-clinorium, seven CBM reservoirs are divided in the Huainan Coalfield, such as Caijiagang, and the dynamic mechanism of CBM forming is analyzed. The structural position where the CBM reservoir is located has the important controlling role on the features of CBM reservoir.
