水文地质条件对低煤阶煤层气成藏的控制作用

低煤阶煤层气富集成藏具有自身独特的特点。为了研究水文地质条件对低煤阶煤层气成藏的控制作用，对美国粉河盆地和我国准噶尔盆地进行了对比研究。结果发现：在影响低煤阶煤层气富集成藏的因素中，水文地质条件是其中最为重要的因素之一，它主要通过影响低煤阶二次生物气来影响煤层气富集程度。粉河盆地的甲烷风化带由于受到第四纪冰期以及二次生物气的影响，变得很浅；而中国西北地区由于干旱，二次生物气少，煤层甲烷风化带却很深。进一步分析还发现，正是进入第四纪以来的气候演化差异造成了不同的水文地质条件，最终导致了中、美两国在低煤阶煤层气富集成藏方面的巨大差异。

CONTROL OF HYDROGEOLOGICAL CONDITIONS ON ACCUMULATION OF COALBED METHANE IN LOW RANK COAL

Enrichment and accumulation of coalbed methane in low rank coal have their own unique characteristics. In order to understand the control of hydrogeological conditions on accumulation of coalbed methane in low rank coal, a comparison study is carried out between the Powder River basin in America and the Juggar basin in China. It is found that among the factors influencing the enrichment and accumulation of coalbed methane in low rank coal, hydrogeological condition is one of the most important factors and it influences the enrichment of coalbed methane through affecting the secondary biogas in low rank coal. The weathered zone containing coalbed methane is very shallow in the Powder River basin due to the influences of the Quaternary glaciation and secondary biogas. In contrast, the weathered zone containing coalbed methane in Northwest China is very deep due to the dry weather and less secondary biogas. Further analysis shows that it is the difference of climate evolution since the Quaternary that results in the variation of hydrogeological conditions, and finally causing the great difference of coalbed methane accumulation in low rank coal between China and America.