Figure
1.
Structure outline, section map and stratigraphic column of Enhong syncline.
| Citation: | Fengjuan Lan, Yong Qin, Ming Li, Yucheng Lin, Aikuan Wang, Jian Shen. Abnormal Concentration and Origin of Heavy Hydrocarbon in Upper Permian Coal Seams from Enhong Syncline, Yunnan, China. Journal of Earth Science, 2012, 23(6): 842-853. doi: 10.1007/s12583-012-0294-x
|
The molecular compositions of coalbed gas (CBG) mainly are CH4, heavy hydrocarbon (C2+), N2, and CO2, which can be classified into dry gas (concentration of C2+ < 5%) and wet gas (concentration of C2+ > 5%). CBG in China is generally characterized by dry gas. However, in some cases, the concentration of C2+ is up to 5% to 25% and even greater than the concentration of methane (Wu, 1994), which we call abnormal concentration of C2+, such as in some parts of eastern Yunnan Province, western Guizhou Province, Chongqing City, central Jiangxi Province, southern Jiangsu Province, northern Zhejiang Province, and western Liaoning Province (He and Qin, 2007; Zhang et al., 2002). In the Enhong syncline of eastern Yunnan Province, the concentration of ethane in CBG varies from 4.38% to 33.90%, with an average value of 16%, and that of propane ranges from 0.7% to 5.88%, generally less than 3% (Wu et al., 2003).
Discussion on the origin of abnormal high concentration of heavy hydrocarbon in CBG is very valuable to understand the CBG source, to optimize CBG utilization, and to prevent gas disasters in coalmines. Previous interpretations have suggested the gas-generating parent material, exogenous oil and gas mixture, contact metamorphism, and coalification stage (Qin et al., 1998; Rice, 1993; Yu and Li, 1981).
Wu (1994) suggested that hydrocarbon displacement effects (larger molecules take up the available pore to accumulate and make the smaller ones migrate), different adsorption of coal to various gas components (adsorption ability of coal to C2+ is larger than CH4), and molecular sieving effects of micropore in coal (larger molecules are controlled in the pores for their sizes and smaller molecules are easier to migrate) could account for the abnormal composition. However, although abnormal concentration of heavy coalbed hydrocarbons in Enhong syncline has received growing attention for many years, detailed studies on its origin have been very limited thus far.
Enhong syncline is located in eastern Yunnan Province, South China, where the Upper Permian coal-bearing strata are included in the Xuanwei Formation (Fig. 1). The thickness of the strata varies from 205 to 335 m, averaging 250 m, and total thickness of the coal seams ranges from 15.99 to 67.68 m, with an average of 18.04 m. Lithologies of lower Xuanwei Formation are gray siltstone and fine sandstone with wave bedding, those of middle section mainly are shallow sandy mudstone with horizontal bedding, and those of upper section are green gray sandy mudstone, fine sandstone, siltstone, and coal. Enhong syncline is a large synclinorium whose main axis extends in a near NNE to SN direction, with numerous secondary folds separated by the major faults and cut by numerous associated and/or induced fractures (Fig. 1).
Data in this article come from coalmines and CBG wells in the Enhong syncline. Basic information on the coals in this area was derived from data from 1 208 boreholes drilled in the coal geological exploration. Coal samples for the basic experiments are from boreholes with monolayer coal thickness equal to or greater than 0.6 m. Petrographic, proximate, and ultimate analyses of the coal samples and molecule composition and gas content of gas samples are carried out in laboratories of exploration teams. Table 1 summarizes the 1 208 borehole data and Tables 2 and 3 show the statistics of 118 borehole data of gases containing abnormal heavy hydrocarbon.
|
DownLoad:
CSV
|
DownLoad:
CSV
|
DownLoad:
CSV
Data in Table 4 were derived from CBG in SJ-01 well. Three gas samples were taken from each sample desorption canister for compositional analysis. The gas content measurements were executed following the Xi'an Branch's specification for gas content measuring and referring to the direct method of American Mining Bureau's standards. The analysis of gas composition follows the National Standard GB/T 13610-1996. Proximate analysis follows the National Standard GB/T 212-1991. The ultimate analysis measuring follows the National Standard GB/T 476-2001. The maceral composition determination follows the National Standard GB/T 8899-1998. The vitrinite reflectance determination follows the National Standard GB/T 6948-1998.
Table 1 shows the organic composition, proximate, and ultimate data of the coal seams studied. The ash yields of the samples vary from 4.76% to 49.59%, with an average value of 22.81%, which suggest medium-high ash coals. The ash yields in the middle part of the formation are lower than in the top and bottom parts (coal seams below No. 21 and above No. 7-1). No. 9 coal seam has the lowest ash yield, with an average value of 16%.
Total sulfur content of the samples varies from 0.06% to 28.00%, with an average of 1.88%, which indicates very low to high sulfur coals. In vertical profile, total sulfur decreases significantly from base to top, whereas, in horizontal distribution, the northwestern part of the syncline is obviously higher than the southeastern part. Volatile yield of the samples varies from 18.84% to 24.83%, with an average of 21.11% and increases from bottom to top in vertical profile and from southeast to northwest in horizontal distribution.
Lithotypes of the coal seams in Enhong syncline are dominated by clarain and durain. The main maceral component is vitrinite and ranges from 50.3% to 97.8%, averaging 74%. The content of inertinite varies between 1.0% and 41.4%, averaging 18%. Liptinite content is very low, usually less than 1%. Inorganic components are dominated by clay minerals (12%) and secondly by quartz (1%–20%) and sulfide (0–3.6%).
Coal rank changes regularly in Enhong syncline with a coal rank increase from northwest to southeast. In vertical profile, the deeper the coal seam buried, the higher coal rank is.
Characteristics of content and concentration of heavy hydrocarbon in CBG, in Enhong syncline, are summarized according to desorption data of 118 coal cores, about 224 samples (Table 2). The mean values of the concentration of heavy hydrocarbon in these samples vary from 1.94% to 14.95%. The minimum mean value is from No. 4+1 coal seam, whereas the maximum is from No. 15 coal seam. The maximum values of heavy hydrocarbon's concentration of these samples vary from 2.90% to 36.98%, the minimum and maximum of which are from Nos. 3 and 13 coal seams, respectively. Coal seams whose concentration is larger than 30% are Nos. 6, 7, 9, 13, and 23 coal seams. The mean value of heavy hydrocarbon's content of these samples varies from 0.10 to 1.03 m3/t and shows the minimum value in No. 4+1 coal seam and the maximum value in No. 15 coal seam. The maximum value of heavy hydrocarbon's content varies from 0.16 to 2.86 m3/t, the minimum and maximum of which are from Nos. 4+1 and 7 coal seams, respectively.
Minefields appearing abnormal heavy hydrocarbon in Enhong syncline include Laoshuzhuo minefield, Zhongduannanbu minefield, Zhengji coalmine, Bumu coalmine, Dahe coalmine, Daping exploration area, Wudeli minefield, and Shidongshan exploration area (Fig. 2). Concentrations of C2+ are between 2.92% and 34.6% in Laoshuzhuo minefield, with an average of 18.04% (Table 3); 1.06% and 30.72% in Shidongshan exploration area, with an average of 10.99%; 0.75% and 36.98% in Daping exploration area, with an average of 10.79%; 0.30% and 25.51% in Bumu coalmine, with an average of 10.37%; 0.12% and 24.99% in Dahe coalmine, with an average of 9.94%; 0.25% and 27.34% in Zhongduannanbu minefield, with an average of 8.42%; 0.26% and 12.05% in Zhengji coalmine, with an average of 4.90%.
Coal seams with high abnormal heavy hydrocarbon are (Fig. 3) Nos. 5, 4+1, 6, 7, 7-1, 8, 8+1, 9, 11, 12, 13, 14, 15, 15a, 15b, 16, 17+1, 18, 19, 19a, 19b, 21, 23, and 23b coal seams, which indicate that abnormal high heavy hydrocarbon is not limited to few coal seams. Among them, No. 9 coal seam has the most samples that contain abnormal concentrations of heavy hydrocarbon, and the concentrations are also high. The No. 7 coal seam takes second place, and the maximum value happened in No. 13 coal seam.
The reason for abnormal high concentration of heavy hydrocarbon can be discussed from the aspects of origin and evolution of heavy hydrocarbons. The abnormal concentrations may originate from the coal seam itself due to its gas-generating parent material or from exogenous reservoirs outside the coal seam, which could be organic gas (petroliferous gas) or inorganic gas. Evolution is reflected in the generation of heavy hydrocarbon changing orderly along with the rising of coal rank. The reason of abnormal high heavy hydrocarbon in Enhong syncline will be analyzed from the aspects of carbon isotope, coal petrography, and coal rank.
Research shows that the carbon isotope composition of CBG is inherited from the characteristics of the parent material. It is also related to the degree of thermal evolution of the organic matter, biological actions, exchange equilibrium effects between CH4 and CO2, and fractionation effects in the process of desorption-diffusion-migration (Shen et al., 2007; Gao et al., 2002; Zhang and Tao, 2000; Qin et al., 1998; Dai et al., 1986; Qi, 1985). Carbon isotopes have become an indispensable part to study the origin of CBG. Characteristics of carbon isotopes of CBG in the Enhong syncline are (Table 4): δ13C1 is between -50.1‰ and -47.0‰, with an average of -48.43‰; δ13C2 is between -25.9‰ and -24.5‰, with an average of -25.1‰; δ13C3 is between -22.3‰ and -16.9‰, with an average of -19.6‰; and δ13CO2 is between -10.8‰ and -2.5‰, with an average of -6.53‰.
|
DownLoad:
CSV
The carbon isotope distribution pattern of alkane gases can be divided into three types by Dai et al.: organic genetic alkane gas characterized by normal carbon isotopic distribution, inorganic alkane gas characterized by negative carbon isotopic distribution, and secondary modified gas characterized by reversal trend of alkane gas carbon isotope (Dai et al., 2008). Carbon isotope in Enhong syncline belongs to the normal carbon isotopic distribution (δ13C1 < δ13C2 < 13C3), which indicates that heavy hydrocarbon in it is organic gas and not inorganic gas.
Organic gas can be divided into coal-type gas (gas generated by humic organic matter) and oil-type gas (gas generated by sapropelic organic matter) according to parent material. Many scholars think that δ13C2 is a very important indicator to recognize the origin of organic gas. Wang thought that δ13C2 higher than -29‰ is a mark of coal-type gas (Wang, 1994). Dai et al. indicated that natural gas has δ13C2 higher than -27.5‰ and δ13C3 higher than -25.5‰ is coal-type gas (Dai et al., 2002). Fu et al. summarized predecessors' discriminant indexes: when Ro, max is between 0.5% and 2.5%, gas whose δ13C1 is greater than -30‰ is classified as coal-type gas, whereas, if lighter than -30‰, it is classified as oil-type gas; gas whose δ13C2 and δ13C3 greater than -25.1‰ and -23.2‰, respectively, is coal type, and gas whose δ13C2 and δ13C3 lighter than -28.8‰ and -25.5‰, respectively, is oil type (Fu et al., 2007). δ13C2 of CBG in Enhong syncline is between -25.9‰ and -24.5‰, with an average of -25.1‰; δ13C3 is between -22.3‰ and -16.9‰, with an average of -19.6‰. Judging from δ13C2 and δ13C3, gas in Enhong syncline belongs to coal type. However, δ13C1 varying from -50.1‰ to -47.0‰, with an average of -48.43‰, is obviously lighter compared with δ13C1 of thermogenic coal gas (> -30‰). From these results, it can be supposed that CBG in Enhong syncline is coal-type gas, and there is no oil-type gas coming from reservoir outside the coal seam. The reason why δ13C1 becomes obviously lighter may be that the coal has been influenced by microorganism.
Coal-type gas can be divided into thermogenetic gas and biogenic gas. δ13C1 of biogenic gas is usually about -55‰ to -90‰, and δ13C1 of thermogenetic gas is usually greater than -50‰ (Fu et al., 2007). δ13C1 in Enhong syncline is between -50.1‰ and -47.0‰, with an average of -48.43‰, greater than -55‰, which meets the standards of thermogenetic gas. In natural gas research, it is generally acknowledged that the origin of CO2 could be divided into biogenic (organic) or abiogenic (inorganic) origin. δ13CCO2 is also a very important indicator that can reflect the origin of CBG. Dai et al.'s (1993) research showed that δ13CCO2 of organic CO2 is usually between -39‰ and -8‰. Kotarba's study showed that δ13CCO2 produced by pyrolysis of humic organic is usually between -25‰ and -5‰ (Kotarba, 2001). δ13CCO2 of CBG in Enhong syncline is between -10.89‰ and -2.59‰, with an average of -6.54‰, which can be ascribed to the thermogenic gas. The reasons of some δ13CCO2 being greater than -5‰ will be discussed later.
Concentrations of CO2 and δ13CCO2 in Enhong syncline are positively correlation (Fig. 4). Both of them are the highest and two to four times higher than other coal seams in No. 9 coal seam. Origin of CO2 can be known by discussing the relationship between CDMI value (also called CO2-CH4 coefficient, which is CO2/(CO2+CH4)×100%) and δ13CCO2. Figure 5 shows that CO2 of CBG in Enhong syncline belongs to category of thermogenic gas produced by humic material, except CO2 in No. 9 coal seam, which is biogenic gas. The reason may be that No. 9 coal seam is easier affected by microorganisms due to its shallow burial depth. That may also be the reason why δ13CCO2 in No. 9 coal seam is greater than 5‰. δ13CCO2 became greater because of the reducing action of microorganisms, which is in agreement with Fig. 4 showing that No. 9 coal seam contains associated CO2 of microorganism methane.
According to the analysis above, it is thought that CBG in Enhong syncline is organic thermogenic gas. Shallow coal seam is affected by microorganism, making δ13C1 in it lighter and δ13CCO2 heavier, with characteristic of secondary biogenic gas.
The ability of coals to generate hydrocarbons strongly depends on their maceral composition, and as a general rule, liptinite-rich coals are oil-prone, whereas vitrinite-rich coals are gas-prone (Alsaab et al., 2007; Petersen and Nytoft, 2006). Predecessors had different opinions on relationship on maceral and concentration of heavy hydrocarbon. Some authors consider that a high content of heavy hydrocarbons is related to higher liptinite content (Alsaab et al., 2008). Some authors (Killops et al., 1998; Bertrand, 1984) did not observe any clear relationship between the liptinite content and the capability for oil generation and found that coal poor in liptinite may possess the capacity to generate oil. Some other authors (Suggate, 2002; Wilkins and George, 2002; Killops et al., 2001; Rice, 1993; Bertrand, 1984) consider that some vitrinite group macerals, such as desmocollinite, are more and more recognized to have the potential for oil generation.
Concentrations of heavy hydrocarbon have a close connection with contents of vitrinite and inertinite in Enhong syncline. The concentrations increase with the increase of vitrinite and decrease with the increase of inertinite (Fig. 6a). The relationship between concentration of heavy hydrocarbon and the content of liptinite is not obvious, with a weakly positive correlation (Fig. 6b).
Inertinite is carbon-rich and oxygen-rich, whereas vitrinite is carbon-rich and hydrogen-rich. Correlations between hydrogen in vitrinite and the concentration of heavy hydrocarbons will be investigated by separately discussing the relationships between heavy hydrocarbons and vitrinite/inertinite ratio (V/I) and the hydrogen/carbon ratio (H/C). Figure 7 shows that the concentration of heavy hydrocarbons increases with the increase of V/I and H/C. From the above analysis, the heavy hydrocarbon in Enhong syncline has a positive correlation to hydrogen-rich degree of vitrinite, demonstrating that to a large extent heavy hydrocarbon comes from hydrogen-rich vitrinite.
Hydrogen-rich vitrinite as an important parent material of coal-formed oil has attracted many people's attention (Petersen and Rosenberg, 1998; Cheng and Zhang, 1994; Bertrand, 1984). The main contributors for oil generation by coal in the typical coal-formed oil basin Tuha basin are desmocollinites (which belong to hydrogen-rich vitrinite) and suberinite (Cheng and Zhang, 1994). Although the hydrocarbon generation potential of vitrinite is lower than that of liptinite, quantity can compensate quality. For most humic coals, the hydrocarbon potential depends not only on the content of liptinite plus sapropelinite but also on the type and content of vitrinite, which may be the more important factor, especially the content of hydrogen-rich vitrinite (Li et al., 1997). The coal maceral composition in Enhong syncline is dominated by vitrinite, with little liptinite, and heavy hydrocarbon has a strong positive correlation with the extent of hydrogen-rich vitrinite, so the parent material is a very important factor to explain the origin of abnormal concentration of heavy hydrocarbons in Enhong syncline, especially the effect of vitrinite and its submacerals on the generation of heavy hydrocarbon.
Thermal simulation experiment of lignite indicates that the peak stage of heavy hydrocarbon generation is in the middle coalification bituminous stage, especially in the fat coal to coking coal stage in which concentration of heavy hydrocarbons could reach 10% (Fu et al., 2007; Petersen, 2006). Ro, max of coal seams in Enhong syncline is between 1.14% and 1.88%, equal to the coking coal to lean coal stage. Figure 8 shows that the concentration of heavy hydrocarbons increases with increasing Ro, max. Ro, max of coal seams is between 1.34% and 1.88% in Laoshuzhuo minefield in which concentration of heavy hydrocarbon is the most abnormal. This relationship indicates that coalification may be one of the factors resulting in abnormal concentration of heavy hydrocarbon.
This article describes the characteristic of abnormal high concentration of heavy hydrocarbons in Enhong syncline and analyzed its reasons from the aspects of origin and evolution of heavy hydrocarbon by carbon isotope, coal petrography, and coal rank.
1. Carbon isotopes of methane, ethane, and propane of coal gas in Enhong syncline have a normal carbon isotopic distribution, which displays the characteristics of organic gas. According to the characteristic of concentration of CO2 and carbon isotope and the relationships among them, coal gas in Enhong syncline is classified as thermogenetic gas produced by humic material, with characteristic of secondary biogenic gas in shallow coal seam.
2. The concentration of heavy hydrocarbons in Enhong syncline increases with the increase of vitrinite and decreases with the increase of inertinite and also increased with the increase of V/I and H/C, so hydrogen-rich vitrinite may be a very important factor resulting in the abnormal concentration of heavy hydrocarbon.
3. The degree of coalification of coal in Enhong syncline is in the coking coal to lean coal stage in which abundant heavy hydrocarbons are generated. Concentration of heavy hydrocarbon increases with the increase of Ro, max. Therefore, coalification may be one of the factors that resulted in abnormal concentration of heavy hydrocarbon.
In conclusion, high concentration of heavy hydrocarbons originates from the coupling effect of higher contents of hydrogen-rich vitrinite in the coal and the coal rank of coking to lean coals during which the peak of heavy hydrocarbon generation is reached.
This study was supported by the National Natural Science Foundation of China (No. 40730422), the National Science and Technology Key Special Project of China (No. 2011ZX05034), and the Fundamental Research Funds for the Central Universities of China (No. 2010QNA51).
| Alsaab, D., Elie, M., Izart, A., et al., 2008. Comparison of Hydrocarbon Gases (C1–C5) Production from Carboniferous Donets (Ukraine) and Cretaceous Sabinas (Mexico) Coals. International Journal of Coal Geology, 74: 154–162 doi: 10.1016/j.coal.2007.11.006 |
| Alsaab, D., Suarez-Ruiz, I., Elie, M., et al., 2007. Comparison of Generative Capacities for Bitumen and Gas between Carboniferous Coals from Donets Basin (Ukraine) and a Cretaceous Coal from Sabinas-Piedras Negras Basin (Mexico) during Artificial Maturation in Confined Pyrolysis System. International Journal of Coal Geology, 71: 85–102 doi: 10.1016/j.coal.2006.09.006 |
| Bertrand, P., 1984. Geochemical and Petrographic Characterization of Humic Coals Considered as Possible Oil Source Rocks. Organic Geochemistry, 6: 481–488 doi: 10.1016/0146-6380(84)90071-8 |
| Cheng, K. M., Zhang, C. F., 1994. Research of Coal-Formed Oil in Tulufan-Hami Basin. Science in China (Series B), 24(11): 1216–1222 (in Chinese) |
| Dai, J. X., Qi, H. F., Song, Y., et al., 1986. Coalbed Methane Composition and Carbon Isotope Types in China and Their Cause and Significance. Science in China (Series B), 12: 1317–1326 (in Chinese) |
| Dai, J. X., 1993. Carbon and Hydrogen Isotope Characteristics of Natural Gas and Authentication of Various Natural Gases. Natural Gas Geoscience, 2–3: 1–40 (in Chinese) |
| Dai, J. X., Xia, X. Y., Hong, F., 2002. Natural Gas Geology Accelerated the Growth of Natural Gas Reserve in Large Scale in China. Xinjiang Petroleum Geology, 23(5): 357–365 (in Chinese with English Abstract) http://en.cnki.com.cn/Article_en/CJFDTOTAL-XJSD200205000.htm |
| Dai, J. X., Ni, Y. Y., Li, J., et al., 2008. Carbon Isotope Types and Significances of Alkane Gases from Junggar Basin and Tarim Basin. Xinjiang Petroleum Geology, 29(4): 403–410 (in Chinese with English Abstract) http://en.cnki.com.cn/Article_en/CJFDTOTAL-XJSD200804003.htm |
| Fu, X. H., Qin, Y., Wei, C. T., 2007. Coalbed Methane Geology. China University of Mining and Technology Press, Xuzhou (in Chinese) |
| Gao, B., Tao, M. X., Zhang, J. B., et al., 2002. Distribution Characteristics and Controlling Factors of δ13C1 Value of Coalbed Methane. Coal Geology and Exploration, 30(3): 14–17 (in Chinese with English Abstract) http://en.cnki.com.cn/Article_en/CJFDTOTAL-MDKT200203004.htm |
| He, T. C., Qin, Y., 2007. Exploration and Development of Coalbed Methane and Its Utilization Technology. China University of Mining and Technology Press, Xuzhou (in Chinese) |
| Kotarba, M. J., 2001. Composition and Origin of Coalbed Gases in the Upper Silesian and Lublin Basins, Poland. Organic Geochemistry, 32: 163–180 doi: 10.1016/S0146-6380(00)00134-0 |
| Killops, S. D., Funnell, R. H., Suggate, R. P., et al., 1998. Predicting Generation and Expulsion of Paraffinic Oil from Vitrinite-Rich Coals. Organic Geochemistry, 29(1–3): 1–21 http://hal.upmc.fr/docs/00/15/69/51/PDF/KILLOPS.pdf |
| Killops, S., Walker, P., Wavrek, D., 2001. Maturity-Related Variations in the Bitumen Compositions of Coals from Tara-1 and Toko-1 Wells. New Zealand Journal of Geology and Geophysics, 44: 157–169 doi: 10.1080/00288306.2001.9514932 |
| Li, X. Q., Ma, A. L., Zhong, N. N., 1997. Research Method and Application of Organic Petrology of Source Rock. Chongqing University Press, Chongqing (in Chinese) |
| Petersen, H. I., Rosenberg, P., 1998. Reflectance Retardation (Suppression) and Source Rock Properties Related to Hydrogen-Enriched Vitrinite in Middle Jurassic Coals, Danish North Sea. Journal of Petroleum Geology, 21(3): 247–263 doi: 10.1111/j.1747-5457.1998.tb00781.x |
| Petersen, H. I., 2006. The Petroleum Generation Potential and Effective Oil Window of Humic Coals Related to Coal Composition and Age. International Journal of Coal Geology, 67: 221–248 doi: 10.1016/j.coal.2006.01.005 |
| Petersen, H. I., Nytoft, H. P., 2006. Oil Generation Capacity of Coals as a Function of Coal Age and Aliphatic Structure. Organic Geochemistry, 37: 558–583 doi: 10.1016/j.orggeochem.2005.12.012 |
| Qi, H. F., 1985. Preliminary Comment on the Variation of Carbon Isotopic Composition of Methane in Coal Measure Gas and Seam Gas, and Its Controlling Factor. Experimental Petroleum Geology, 7(2): 81–84 (in Chinese with English Abstract) http://www.sysydz.net/EN/Y1985/V7/I2/81 |
| Qin, Y., Tang, X. Y., Ye, J. P., 1998. Stable Carbon Isotope Composition and Desorption Diffusion Effect of the Upper Paleozoic Coalbed Methane in North China. Geological Journal of China Universities, 4(2): 127–132 (in Chinese with English Abstract) http://en.cnki.com.cn/Article_en/CJFDTOTAL-GXDX802.001.htm |
| Rice, D. D., 1993. Composition and Origins of Coalbed Gas. In: Law, B. E., Rice, D. D., eds., Hydrocarbons from Coal. Halifax, N1S, Canada. AAPG Special Publication, 159–184 |
| Shen, B. J., Huang, Z. L., Liu, H. W., et al., 2007. Advances in the Study of Gas and Source Rock Correlation. Natural Gas Geoscience, 18(2): 269–274 (in Chinese with English Abstract) https://www.oalib.com/paper/1417841 |
| Suggate, R. P., 2002. Application of Rank (Sr), a Maturity Index Based on Chemical Analyses of Coals. Marine and Petroleum Geology, 19: 929–950 doi: 10.1016/S0264-8172(02)00117-4 |
| Wang, S. Q., 1994. Geochemical Characteristics of Jurassic-Sinian Gas in Sichuan Basin. Natural Gas Industry, 14(6): 1–5 (in Chinese with English Abstract) http://www.trqgy.cn/EN/Y1994/V14/I6/1 |
| Wilkins, R. W. T., George, S. C., 2002. Coal as a Source Rock for Oil: A Review. International Journal of Coal Geology, 50: 317–361 doi: 10.1016/S0166-5162(02)00134-9 |
| Wu, G. Q., Lin, Y. C., Li, Y. B., 2003. Occurrence Characteristic of Coalbed Methane Resouse in Enhong and Laochang Mine Area. Jiangsu Coal, (3): 26–27 (in Chinese) |
| Wu, J., 1994. Theory and Applications of Coal-Derived Hydrocarbon in China. China Coal Industry Publishing House, Beijing (in Chinese) |
| Yu, L. C., Li, W. F., 1981. Study on Composition of Hydrocarbons in Coal Seams Liable to Outbursts. Journal of China Coal Society, 4: 1–8 (in Chinese with English Abstract) http://www.cnki.com.cn/Article/CJFDTotal-MTXB198104000.htm |
| Zhang, J. B., Tao, M. X., 2000. Geological Significances of Coal Bed Methane Carbon Isotope in Coal Bed Methane Exploration. Acta Sedimentologica Sinica, 18(4): 611–614 (in Chinese with English Abstract) |
| Zhang, X. M., Zhuang, J., Zhang, S. A., 2002. Coalbed Methane Geology and Resource Evaluation in China. Science Press, Beijing (in Chinese) |
Figures(8) / Tables(4)
Copyright © 2013-2020 Journal of Earth Science 鄂ICP备15021562号-2
Tel: +86-27-67885075 Fax: +86-27-67885075 E-mail: xbb@cug.edu.cn
Address: Editorial Office of Journal, China University of Geosciences, Yujiashan, Wuhan, Hubei 430074, P. R. China
Supported by:
Beijing Renhe Information Technology Co. Ltd
E-mail:
info@rhhz.net
Fengjuan Lan, Yong Qin, Ming Li, Yucheng Lin, Aikuan Wang, Jian Shen. Abnormal Concentration and Origin of Heavy Hydrocarbon in Upper Permian Coal Seams from Enhong Syncline, Yunnan, China. Journal of Earth Science, 2012, 23(6): 842-853. doi: 10.1007/s12583-012-0294-x
|
|
DownLoad:
CSV
|
|
DownLoad:
CSV
|
|
DownLoad:
CSV
|
|
DownLoad:
CSV
DownLoad:
DownLoad:
