不同方法测试煤层气含量时重烃浓度的比较分析

摘要

To study heavy hydrocarbon concentration difference and its impacting on the vacuum degassing method and natural desorp⁃tion method to test CBM content, taking the Jurassic Yanan Formation coal No.3 in the Changwu coalfield as the subject investigated, compared different heavy hydrocarbon concentrations in CBM samples using the two method to test CBM content of coal core samples from same borehole and same coal seam. The tested result has shown that the heavy hydrocarbon concentrations in the vacuum degas⁃sing method before and after the sample crushing are larger than those in natural desorption method 1.97 and 2.63 times respectively. Taking coal core samples from 9 boreholes as example, using vacuum degassing method test, compared heavy hydrocarbon concentra⁃tions tested from a same coal core under different temperatures and grain-sizes have found that the heavy hydrocarbon concentration is larger when the temperature higher and grain-size smaller, thus temperature and coal core grain-size are the major impacting factors on heavy hydrocarbon concentration in gas samples.%为研究瓦斯脱气法和自然解吸法测试煤层气含量时气样中重烃浓度的差异及影响因素，以陕西长武煤田侏罗系延安组3煤层为对象，比较了两种方法测试同一钻孔、同一煤层的煤心样品时气样中的重烃浓度，测试结果显示，瓦斯脱气法粉碎前和粉碎后重烃浓度分别为自然解吸法的1.97倍和2.63倍；以9个钻孔的煤心样品为例，采用瓦斯脱气法测试，将同一煤心样品在不同温度、不同粒度所得重烃的浓度进行比较，实验温度高、煤心粒度小时，重烃浓度较大，即温度和煤心粒度是影响气样中重烃浓度大小的主要因素。