地学前缘 ›› 2010, Vol. 17 ›› Issue (5): 325-335.

• 论文 • 上一篇    下一篇

不同变质变形煤储层孔隙特征与煤层气可采性

范俊佳,琚宜文,侯泉林,谭静强,卫明明   

  1. 中国科学院 研究生院 地球科学学院, 北京 100049
  • 收稿日期:2010-04-16 出版日期:2010-09-15 发布日期:2010-10-22
  • 作者简介:范俊佳(1984—)，女，硕士，构造地质学专业，现从事构造地质与煤层气地质方面研究。E-mail: fanjunjia07@mails.gucas.ac.cn
  • 基金资助:

    国家重点基础研究发展计划“973”项目(2009CB219601,2006CB202201);国家自然科学基金项目(40772135,40972131,40172058);国家科技重大专项(2009ZX05039003,2009ZX05039004)

Pore structure characteristics of different metamorphicdeformed coal reservoirs and its restriction on recovery of coalbed methane.

  1. College of Earth Science, Graduate University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2010-04-16 Online:2010-09-15 Published:2010-10-22

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摘要：

煤储层孔隙是煤层气的主要聚集场所和运移通道,煤储层孔隙结构不仅制约着煤层气的含气量,而且对其可采性也有重要影响。文中选取淮北煤田和沁水盆地不同矿区有代表性的煤样,通过对研究区不同变质与变形煤样的宏微观构造观测、镜质组反射率与孔隙度测试以及压汞实验分析,研究了不同变质变形煤储层孔隙结构特征及其对煤层气可采性的制约。研究结果表明,按照不同的变质变形特征将研究区煤储层主要划分为5类,即:高变质较强至强变形程度煤储层(Ⅰ类)、高变质较弱变形程度煤储层(Ⅱ类)、中变质较强变形程度煤储层(Ⅲ类)、中变质较弱变形程度煤储层(Ⅳ类)及低变质强变形程度煤储层(Ⅴ类)。不同变质变形煤储层的孔隙结构具有以下特征:Ⅰ类和Ⅱ类煤储层吸附孔占主导,Ⅰ类煤储层孔隙连通性差,Ⅱ类煤储层因后期叠加了构造裂隙,孔隙连通性变好;Ⅲ类煤储层中孔、大孔增多,但有效孔隙少,孔隙连通性变差;Ⅳ类煤储层吸附孔较多,中孔、大孔中等,且煤储层内生裂隙发育,孔隙具有较好的连通性,渗透性明显变好;Ⅴ类煤储层吸附孔含量较低,中孔较发育,大孔不太发育,有效孔隙少,孔隙连通性差。由此,变质程度高且叠加了一定构造变形的煤储层(Ⅱ类)以及中等变质程度变形较弱且内生裂隙发育的煤储层(Ⅳ类),其煤层气有较好的渗透性,可采性较好。

关键词: 变质变形类型, 煤储层, 镜质组反射率, 孔隙结构, 煤层气, 可采性

Abstract:

In the coal reservoir, the pore of coal is the main accumulation area and migration pathways of coalbed methane. The pore structure not only controls the gas content but also has significant influence on the coalbed methane recovery. On the basis of macromicro observation, vitrinite reflectance and porosity testing, and mercury injection experiment of different metamorphicdeformed coal samples collected from the Huaibei coalfield and Qinshui basin, we studied the pore structure characteristics and its restriction on the recovery of coalbed methane. According to  analysis of experiment data and field observation of representative coal samples in the study area, the coal reservoirs are mainly classified under five different metamorphicdeformed types: the high grade metamorphic and medium deformed to strongly deformed coal reservoir (typeI); the high grade metamorphic and comparatively weakly deformed coal reservoir (typeII); the medium grade metamorphic and comparatively strongly deformed coal reservoir (typeIII); the medium grade metamorphic and comparatively weakly deformed coal reservoir (typeIV); and the low grade metamorphic and strongly deformed coal reservoir (typeV). Furthermore, pore structure characteristics are different among these different types of coal reservoirs. There are more adsorption pores in the coal reservoir of typeI than that in other types; however, the pore connectivity is better in the typeII than that in typeI because of tectonic fractures formed by tectonic action in coal reservoirs of typeII. And there are less adsorption pores in reservoir of typeIII than that in coal reservoir of typeI and typeII, and the pore connectivity is unfavorable. The coal reservoir of typeIV is characterized by better gas content and good pore connectivity caused by a large number of cleats and adsorption pores in coals. As for coal reservoir of typeV, the pore connectivity is worse than other types because of the existence of a large number of thinneck bottle type pores. In conclusion, the coal reservoirs of typeII and typeIV are favorable for the recovery of coalbed methane because of the better absorptive capability and permeability.

Key words: metamorphicdeformed type, coal reservoir, vitrinite reflectance, pore structure, coalbed methane, recovery

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