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| 1 | Coalbed methane enrichment model of low-rank coals in multi-coals superimposed regions: a case study in the middle section of southern Junggar Basin显示文摘The Middle Jurassic Xishanyao Formation in the central section of the southern Junggar Basin has substantial amounts of low-ranked coalbed methane(CBM)recourses and is typically characterized by multi superimposed coal seams.To establish the CBM enrichment model,a series of experimental and testing methods were adopted,including coal maceral observation,proximate analysis,low temperature nitrogen adsorption(LTNA),methane carbon isotope determination,porosity/permeability simulation caused by overburden,and gas content testing.The controlling effect of sedimentary environment,geological tectonic,and hydrogeological condition on gas content was analyzed in detail.The results demonstrate that the areas with higher gas content(an average of 8.57 m3/t)are mainly located in the Urumqi River-Santun River(eastern study area),whereas gas content(an average of 3.92 m3/t)in the Manasi River-Taxi River(western study area)is relatively low.Because of the combined effects of strata temperature and pressure,the gas content in coal seam first increases and then decreases with increasing buried depth,and the critical depth of the inflection point ranges from 600 m to 850 m.Affected by the changes in topography and water head height,the direction of groundwater migration is predicted from south to north and from west to east.Based on the gas content variation,the lower and middle parts of the Xishanyao Formation can be divided into three independent coalbearing gas systems.Within a single gas-bearing system,there is a positive correlation between gas content and strata pressure,and the key mudstone layers separating each gas-bearing system are usually developed at the end of each highstand system tract.The new CBM accumulation model of the multi-coals mixed genetic gas shows that both biological and thermal origins are found in a buried depth interval between 600 m and 850 m,suggesting that the coals with those depths are the CBM enrichment horizons and favorable exploration regions in the middle section of the southern Junggar Basin.An in-depth discussion of the low-rank CBM enrichment model with multi-coal seams in the study region can provide a basis for the optimization of CBM well locations and favorable exploration horizons. | Haihai HOU Guodong LIANG Longyi SHAO Yue TANG Guangyuan MU | 2021 | Frontiers of Earth Science2021，15，2： | 2 |
| 2 | Net primary productivity and its control of the Middle Jurassic peatlands: An example from the southern Junggar coalfield显示文摘The Jurassic is an important period of global coal formation, including the development of several large coalfields in central Asia and northern China. Individual seams within these peatlands represent sustained periods of terrestrial carbon accumulation and a key environmental indicator attributed to this record is the rate of carbon accumulation. Determining the rate of carbon accumulation requires a measure of time contained within the coal and this study aimed at determining the rate via the identification of Milankovitch orbital cycles using spectral analysis. Spectral analyses of geophysical data from two thick coal seams, No. 43(35.9 m) and No. 3(13.2 m), of the Middle Jurassic of the southern Junggar coalfield were conducted to identify significant signals of variations in ash content. The results showed that the variations in ash content of the coal showed spatial cycles at 0.2, 0.7 and 1.1 m^(-1), which were interpreted to represent 123 ka(eccentricity), 37.1 ka(obliquity), and 21.2 ka(precession) orbital periodicities, respectively. Using this timeframe, the depositional time of the No. 43 and No. 3 coal seams were calculated to be 876–970 and 322–357 ka, respectively. In combination with an understanding of carbon loss during coalification, the carbon accumulation rates of these Middle Jurassic peatlands were calculated to be 58.6–64.9 and60.3–66.8 g C m^(-2) a^(-1) for the No. 43 and No. 3 coal seams, respectively. Given that the net primary productivity(NPP) was 4.3 times the value of the carbon accumulation in a mid-latitude region of 40°–45°N, an NPP of 251.8–279.1 and259.1–287.1 g C m^(-2) a^(-1) was calculated for the No. 43 and No. 3 coal seams, respectively. In the context of the same paleolatitude(40°–45°N) and peat type, the NPP values of the Middle Jurassic strata in the study area were higher than those of the peatlands of the Holocene and Permian, and were similar to the NPP values of Early Cretaceous peatlands. Considering the NPP of a peatland is predominantly controlled by atmospheric CO_2 and O_2 levels and temperature, the lower content of CO_2 and an excessive O_2 level in the temporal atmosphere would lead to a decrease in peatland NPP. Therefore, it is inferred that the CO_2 level during the Middle Jurassic was higher than that of the icehouse Permian and Holocene periods, and it was similar to the CO_2 level of the greenhouse Cretaceous period. The results are consistent with the global CO_2 variation curve of Berner. In conclusion, Milankovitch orbital cycles calculated from geophysical logs can be used to infer the NPP of temporal peatlands during different geological periods, based on which the deep-time paleoclimates can be analyzed. | Yanan LI Longyi SHAO Zhiming YAN Haihai HOU Yue TANG David J.LARGE | 2018 | Science China Earth Sciences2018，61，11： | 2 |
| 3 | Repeated Wildfires in the Middle Jurassic Xishanyao Formation(Aalenian and Bajocian Ages) in Northwestern China显示文摘The coal-bearing strata in the southern Junggar Basin in northwestern China have recently attracted the attention of coal geologists. Its abundance of coal resources is of great interest as there is a potential of unlocking details about the palaeoclimatic information. Coal deposits have the capacity to record wildfire events, even those with inefficient combustions. To characterize wildfire events and palaeoclimatic history of the Middle Jurassic Xishanyao Formation(Aalenian and Bajocian ages), 22 coal samples from borehole cores and coal mines in the southern Junggar Basin were collected and their macerals were analyzed. The results indicated that fusinite and semi-fusinite were the dominant components of inertinite with proportions of 35.27% and 54.67%, respectively. The presence of inertinite is an indicator that wildfires occurred at the time of peat land development, and the widespread occurrence suggests large scale wildfires during the Middle Jurassic. This study proposes a new parameter for the evaluation of wildfire features by combining burning frequency and burning temperature. The comprehensive evaluation index(CEI) was influenced by the lacustrine basin level and ancient plant types from a sequence framework. During the Middle Jurassic, most wildfires were surface fires with low level and ground fire with high level. High oxygen levels were estimated in the lower, middle, and upper members of the Xishanyao Formation with corresponding to 26.78%, 24.55%, and 23.55%, respectively. The high oxygen levels would be the primary cause of repeated wildfires in the Middle Jurassic. These results are helpful for understanding palaeoclimatic changes in the Middle Jurassic. | HOU Haihai SHAO Longyi LIANG Guodong TANG Yue ZHANG Huajie ZHANG Jiaqiang | 2022 | Acta Geologica Sinica(English Edition)2022，96，5： | 1 |
| 4 | Effect of heat-treatment on the surface properties of gallium phosphide nanosolids by Raman spectroscopy显示文摘Raman spectra of gallium phosphide (GaP) nanosolids (unheated and heat-treated at 598 and 723 K, respectively) were investigated. It was observed that both the longitudinal optical mode (LO) and the transverse optical mode (TO) dis-played an asymmetry on the low-wavenumber side. The scattering bands were fitted to a sum of four Lorentzians which were assigned to the LO mode, surface phonon mode, TO mode, and a combination of Ga?O?P symmetric bending and sum band formed from the X-point TA + LA phonons, respectively. Analysis of the characteristic of surface phonon mode revealed that the surface phonon peak of the GaP nanosolids could be confirmed. In the infrared spectrum of the GaP nanoparticles, we observed the bands on account of symmetric stretching and bending of PO2, as well as stretching of Ga?O. The Raman scattering intensity arising from the Ga?O?P linkages increased as increasing the heat-treatment temperature. | ZHANG Zhaochun YUE Longyi GUO Jingkang | 2006 | Rare Metals2006，25，3： | 1 |
| 5 | Coal Seam Correlation in Terrestrial Basins by Sequence Stratigraphy and Its Implications for Paleoclimate and Paleoenvironment Evolution显示文摘Coal correlation cannot only guide coal and coalbed methane exploitation,but may also provide valuable information for the evolution of the paleoclimate and paleoenvironment during coalaccumulation periods.It is difficult to undertake coal correlation in a terrestrial basin due to multiple superimposed coal seams and a lack of effective marker beds.In this study,based on the analyses of coal-bearing sedimentary environments and the observations of field outcrops and drilling cores,three key sequence surfaces of the Middle Jurassic Xishanyao Formation were identified in the middle part of the southern Junggar Basin.Three third-order sequences(S.Ⅲ1,S.Ⅲ2 and S.Ⅲ3)and ten fourth-order sequences were divided within the Xishanyao Formation.Regional coal correlation was finally identified,combined with the layered vertical pattern coal and its interval thickness,coal maceral,and coal quality data.In terms of the coal correlation within a specific sequence set,the interval of the B2–B3 coals was approximately three times thicker than that of the B3–B5 coals,which was the main marker for regional coal correlation in the Lower Xishanyao Formation.Furthermore,the phenomena of steadily developed B4 coal seam(2–3 m in thickness)across the Liuhuanggou coal mining area(eastern study region)and the large-small-large variation for intervals between the B8 and B9,B9 and B10,and B10 and B11 coal seams in the Manasi coal mining(western study region)were also an effective means for local coal correlation.Increasing vitrinite and sulphur content and decreasing inertinite content in a third-order sequence were found,which were likely to be closely related to lake level fluctuations.Based on the variation of coal macerals,the wildfire frequency gradually decreased from the bottom to the top of the Xishanyao Formation.The predicted O2level of the S.Ⅲ1,S.Ⅲ2,and S.Ⅲ3 of the Xishanyao Formation was 26.36%,24.22%,and 22.51%,respectively.Except for global paleoclimate effects,the provenance direction changes caused by the Bogda Mountains uplifts would result in a regular variation of coal maceral and coal quality across the study region. | Haihai Hou Longyi Shao Yue Tang Yanan Li Guodong Liang Yilin Xin Jiaqiang Zhang | 2023 | Journal of Earth Science2023，34，2： | 0 |
| 6 | Fractal characterization of pore structure and its influence on CH_(4) adsorption and seepage capacity of low-rank coals显示文摘The pore structures of coal can directly affect the adsorption and seepage capacity of coalbed methane(CBM),which therefore is an important influence on CBM exploration and development.In this study,the pore structures of low-rank coals from the Middle Jurassic Xishanyao Formation in the southern Junggar Basin were analyzed,and the fractal dimensions(D1,D2,D3 and D4 corresponding to pore sizes of 0-5 nm,5-100 nm,100-1000 nm and 1000-20000 nm,respectively)were calculated to quantitatively describe these coal pore structures.The results show that Xishanyao coal is characterized by open pore morphology,good pore connectivity and well-developed seepage pores and microfractures,which is beneficial to CBM seepage.The D1 and D2 can be used to characterize the pore surface and structure of adsorption pores respectively.The D3 and D4 can be used to represent the pore structure of seepage pores.Compared with adsorption pores,the structure of seepage pores is more affected by the change of coal rank.The D1 is better than D2 in characterizing the methane adsorption capacity.When D1>2.2,D1 is positively correlated with Langmuir volume(VL)and negatively correlated with Langmuir pressure(PL),while D2 shows a weak opposite trend.The coals with the higher D1 and lower D2 are associated with a higher VL,indicating the coal reservoir with more complex pore surfaces and simpler pore structures has stronger methane adsorption capacity.D4 is better than D3 in characterizing the methane seepage capacity.The porosity and permeability of coal reservoirs increase with the increase of D4,while D3 displays an opposite trend,which is mainly related to the well-developed microfractures.The well-developed fracture system enhances the seepage capacity of the Xishanyao coal reservoir.This study reveals the fractal characteristics of pore structure and its significant influence on adsorption and seepage capacity of low-rank coal. | Guangyuan MU Haihai HOU Jiaqiang ZHANG Yue TANG Ya-nan LI Bin SUN Yong LI Tim JONES Yuan YUAN Longyi SHAO | 2022 | Frontiers of Earth Science2022，16，4： | 0 |
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