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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在改革中前进的环境地质——西安地质矿产研究所环境地质开发研究工作概述     

董发开 《西北地质科学》1992,(2)

为了使科研工作适应于经济建设的需要,我所于1985年10月建立了环境地质开发研究组,1987年扩充成为环境地质开发研究室,专业技术人员由初建时的3人增加到18人。1985-1991年承担环境影响评价、三废治理、综合利用项目以及大型实验合计52项;已完成的有42项,其中有8项获地矿部科技成果3、4等奖。又于1989年获得国家环保局首批颁发的《环境影响评价》甲级证书,有资格参加国家各种规模建设项目和区域环境影响评价工作。现在,环境地质开发研究专业已成为我所3大特色专业之一。  相似文献   

限差内水准测量成果异常的判别     

易法楷 《武汉大学学报(信息科学版)》1986,(4)

如何更合理完善地制定一种判别测量成果质量的标准,是一个很有研究价值的课题。本文对在水准测量中用控制图表充实现行的固定限差法判别测量成果质量作了初步尝试,在统计检验原理的基础上,提出了判别限差内水准测量成果的三条准则。用极其简单、直观的控制图表,能对限差内的成果可能出现的异常及时作出判断。若以此监控水准测量生产,不仅方便可行,且能收到较好的经济效益,更重要的是对提高成果质量也大有裨益。  相似文献