Sampling Methane-Bearing Coal Seams by Freezing Method: Coalbed Methane Desorption and Inhibition Characteristics Under Freezing Temperature     

Wang  Fakai  Luo  Yongjiang  Liang  Yunpei  Peng  Jianming  Li  Baijun 《Natural Resources Research》2020,29(2):1351-1360

Methane content in coal seam is an essential parameter for the assessment of coalbed gas reserves and is a threat to underground coal mining activities. Compared with the adsorption-isotherm-based indirect method, the direct method by sampling methane-bearing coal seams is apparently more accurate for predicting coalbed methane content. However, the traditional sampling method by using an opened sample tube or collecting drill cuttings with air drilling operation would lead to serious loss of coalbed methane in the sampling process. The pressurized sampling method by employing mechanical-valve-based pressure corer is expected to reduce the loss of coalbed methane, whereas it usually results in failure due to the wear of the mechanical valve. Sampling of methane-bearing coal seams by freezing was proposed in this study, and the coalbed gas desorption characteristics under freezing temperature were studied to verify the feasibility of this method. Results show that low temperature does not only improve the adsorption velocity of the coalbed gas, but also extend the adsorption process and increase the total adsorbed gas. The total adsorbed methane gas increased linearly with decreasing temperature, which was considered to be attributed to the decreased Gibbs free energy and molecular average free path of the coalbed gas molecular caused by low temperature. In contrast, the desorption velocity and total desorbed gas are significantly deceased under lower temperatures. The process of desorption can be divided into three phases. Desorption velocity decreases linearly at the first phase, and then, it shows a slow decreases at the second phase. Finally, the velocity of desorption levels off to a constant value at the third phase. The desorbed coalbed gas shows a parabolic relation to temperature at each phase, and it increases with increasing temperature at the first phase, and then, it poses a declining trend with increasing temperature at the rest phases. The experimental results show that decreasing the system temperature can restrain desorption of coalbed methane effectively, and it is proven to be a feasible way of sampling methane-bearing coal seams.

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Characterization and Quantification of Mining-Induced Fractures in Overlying Strata: Implications for Coalbed Methane Drainage     

Zhang  Bichuan  Sun  Haitao  Liang  Yunpei  Wang  Kequan  Zou  Quanle 《Natural Resources Research》2020,29(4):2467-2480

Natural Resources Research - Coalbed methane (CBM) production in the overlying strata of coal reservoirs is often hampered by the unknown distribution of the mining-induced fractures....  相似文献   

一种基于改进克里金法的地面气温质量控制算法     

叶小岭  沈云培  熊雄 《气候与环境研究》2016,21(5):614-620

依据气温间的空间相关性,将地统计学中的普通克里金法(Ordinary Kriging,OK)引入地面气温资料的质量控制。考虑气温在空间上的连续性,提出一种基于高斯模型改进的普通克里金(Improved Ordinary Kriging,IOK)质量控制方法。为评估该方法的性能,运用IOK法对江苏省67个台站2008年地面日平均气温资料进行质量控制,并与OK法以及反距离加权法(Inverse Distance Weighted,IDW)进行比较。试验结果表明,IOK法的检验效果优于OK法与IDW法,且稳定性与适用性较高,能有效地标记出气温观测数据中的可疑数据。  相似文献   

厦门湾瘦枝珊瑚属空间分布及新记录种          下载免费PDF全文

阳静  刘佳英  王云沛  施宜佳 《应用海洋学学报》2023,42(4):604-612

厦门湾是一个集河口、红树林、浅海湿地等多种典型生态系统的海湾，生物多样性高，曾报道有28种八放珊瑚栖息，但未见瘦枝珊瑚属(Carijoa)的相关报道。为了解厦门湾内瘦枝珊瑚属资源现状，本研究于2014—2021年期间在厦门湾内的大佰屿、小佰屿、白哈礁、角屿、上屿、黄厝、鼓浪屿、火烧屿、青屿以及浯屿附近海域通过潜水调查采集珊瑚样本，其中有25株是瘦枝珊瑚属样本。对样本进行形态学鉴定及基因片段[细胞色素C氧化酶亚单位Ⅰ(COⅠ)、NADH脱氢酶第二亚基(ND2)]定序技术研究。结果显示，采集的25株瘦枝珊瑚属样本全部都是Carijoa riisei，这是该种在厦门湾的首次记录。C. riisei分布在厦门湾的小佰屿、白哈礁、上屿、角屿、鼓浪屿和火烧屿附近海域，而大佰屿、黄厝、青屿和浯屿站位未见该物种分布。本研究结果既丰富了厦门湾的珊瑚物种记录，也增加了C. riisei的世界地理分布信息，可为全球Carijoa属珊瑚生物地理信息研究提供数据支撑。  相似文献   

Acoustic Emission and Energy Dissipation Characteristics of Gas-Bearing Coal Samples Under Different Cyclic Loading Paths     

Li  Qingmiao  Liang  Yunpei  Zou  Quanle  Li  Quangui 《Natural Resources Research》2020,29(2):1397-1412

Natural Resources Research - Cyclic loading widely exists in coal mining activities, and it can significantly change the mechanical and seepage characteristics of coal. In this study, raw...  相似文献   

Radiocarbon age anomalies of land snail shells in the Chinese Loess Plateau     

Bing Xu  Zhaoyan Gu  Jingtai Han  Qingzhen Hao  Yanwu Lu  Luo Wang  Naiqin Wu  Yunpei Peng 《Quaternary Geochronology》2011,6(3-4):383-389

In the Chinese Loess Plateau, land snail shells are often the only material available for dating in paleoenvironmental and archaeological research. However, the geochronological suitability of land snail shells is limited because of poor knowledge about their deposition dynamics, particularly with regards to the incorporation of inorganic carbonate and the resulting age anomalies. To evaluate the factors controlling these age anomalies, radiocarbon and stable carbon analyses were carried out on surface soils, as well as the shells and organic bodies of different modern snail species from different ecological habitats. The results showed that all specimens were depleted in ¹⁴C, indicating the influence of inorganic, radiocarbon-free carbonate on the ¹⁴C-activity of the snail shells. The apparent ¹⁴C-deficiencies and the resultant age anomalies of both the Cathaica and the Bradybaena snail shells were within close ranges across the Chinese Loess Plateau, indicating that the shells of these species could, after corrections for radiocarbon anomalies, provide reliable age estimates. The apparent ¹⁴C-deficiencies were closely associated with the ecological habitats of the snails. The shells of the ground-dwelling Bradybaena had the smallest age offsets (533 ± 150 a), followed grass-dwelling Cathaica (1107 ± 138 a) and Cathaica living on trees (1550 ± 345 a). These results suggest that the availability of calcium in the respective ecological habitats is an important factor in explaining the apparent ¹⁴C-deficiencies. The influence of carbonate on the stable carbon isotope composition of shells is overwhelmed by the organic diets of snails, making δ¹³C unsuitable for identifying and correcting shell age anomalies. The radiocarbon activities of surface soils (A_calc) increase with weathering intensity. Thus, a significant uncertainty could be caused by assuming that A_calc is zero when estimating the proportions of different carbon sources in shells, as has been the case in most previous studies.  相似文献   

PSO-PSR-ELM集成学习算法在地面气温观测资料质量控制中的应用   总被引：1，自引：0，他引：1  

张颖超  姚润进  熊雄  沈云培 《气候与环境研究》2017,22(1):59-70

针对台站密度低、新建台站以及特种单要素站等无法获得有效邻站或内部参考资料情况下的质量控制问题,从气温时间序列的混沌特性出发,考虑气温在短时间内的连续性和稳定性,提出一种基于粒子群(Particle Swarm Optimization,PSO)改进的相空间重构法(Phase Space Reconstruction,PSR)和极限学习机(Extreme Learning Machine,ELM)的集成学习算法的地面逐时气温观测资料的单站质量控制方法,实现气温资料的质量控制。为检验该方法的适用性,运用该方法对江苏省八市2007~2009年的地面气温观测资料进行质量控制,并与传统单站方法及切比雪夫多项式内插法(Tshebyshev Polynomial Interpolation,TPI)进行对比。实验结果表明,该方法相比较于TPI和传统方法可以更有效地标记出可疑数据,具有检错率高、地区和气候适应性、可控性强等优点。  相似文献