不同煤阶煤层气选区评价参数的研究与应用

目前,国外煤层气开发主要以中低煤阶为主,而我国则以中高煤阶为主;不同煤阶具有不同的煤层气地质特点与选区评价标准。为此,通过对国内外重点煤层气盆地的煤层气评价参数对比研究,提出了不同煤阶的煤层气选区评价参数,包括:煤层气资源规模及丰度、煤层厚度、煤层含气量、煤层气吸附饱和度、煤层原始渗透率、有效地应力、地解比、构造发育状况及水文地质条件。在此基础上,通过对重点煤层气区的类比分析,初步建立了我国煤层气选区评价标准,并优选出煤层气有利富集区16个:其中Ⅰ类最有利富集区6个,包括沁水盆地南部、阜新盆地刘家区块、鄂尔多斯盆地东部、宁武盆地南部、准噶尔盆地东南部、二连盆地霍林河地区;Ⅱ类有利富集区4个,包括沁水盆地北部、鄂尔多斯盆地乌审旗地区、黔西盘关地区、川南古蔺—叙永地区;Ⅲ类较有利富集区6个。

Research and application of appraisal variables for the prioritizing of coalbed methane areas featured by different coal ranks

At present, the development of coalbed methane (CBM) abroad is dominated by the medium and low coal ranks while that by the medium and high coal ranks at home. Meanwhile, different coal ranks represent distinct geological characteristics and appraisal criteria of different CBM areas. Therefore, a comparison study is made on the appraisal parameters of major CBM basins at home and abroad and the optimized appraisal variables for the prioritizing of CBM areas are presented hereby, including scale and abundance of CBM resources, thickness of coal seam, gas content of coal seam, adsorption saturation of CBM, original coal seam permeability, effective earth stress, the ratio between critical desorption pressure and initial formation pressure, the status of tectonic development, and hydrogeological conditions. Moreover, through an analogy analysis of key CBM gas areas, an appraisal criterion is established for the prioritizing of CBM areas in China and 16 favorable target areas are prioritized as follows:①6 type Ⅰregions, including the southern Qinshui Basin, the Liujia Block of the Fuxin Basin, the eastern Ordos Basin, the southern Ningwu Basin, the southeastern Junggar Basin, the Huolinhe area of the Erlian Basin, ②4 type Ⅱ regions, including the Qinshui Basin, the Wushenqi area of the Ordos Basin, the Panguan area of the western Guizhou, and the Gulin Xuyong area of the southern Sichuan, and ③6 type Ⅲ regions, including the Sanjiang Mulenghe area of North East China, the Yili Yanqi area of Xinjiang, the Pingle area of Jiangxi, the Huhehu area of Haila'er in the Inner Mongolia, the Sha'erhu area of the Tuha Basin, and the Dacheng area of North China. This gives directions for the CBM development in China.