煤层气富集高产区富集机理和地质评价方法对煤层气勘探选区至关重要,以往的研究主要集中在资源富集区形成机理和预测方面,但煤层气勘探开发实践表明资源富集区并不一定是高产区,如何在煤层气资源富集区中寻找高产区即煤层气富集高产区是国内外煤层气勘探面临的难题。通过国内外典型煤层气富集高产区的剖析,结合我国中高煤阶富集区地质特点,以沁水盆地南部、鄂尔多斯盆地东缘和两淮矿区为研究对象,采用地质统计、实验验证和生产数据分析相结合的研究方法,揭示了基于含气量-渗透率耦合控制的煤层气富集高产区形成机理,提出了3种中高煤阶煤层气富集高产区形成模式;围绕煤层含气量和渗透率两个核心要素,利用层次分析法和主成分分析法确定了包含7大地质参数的评价指标体系,建立了基于产能分析的煤层气富集高产区方法体系。这些认识对我国中高煤阶煤层气区带、区块、目标的优选具有重要的指导作用。
Enrichment mechanism and geological evaluation method of coalbed methane (CBM) enrichment and high production areas is crucial for CBM successful exploration. Previous studies have mostly focused on the formation and forecast of CBM resource enrichment areas. However, CBM production practice in a few decades shows that the source enrichment area is not necessarily a high production area. Therefore, a facing challenge in CBM exploration is how to confirm a CBM high production zone in a resource enrichment area. In this paper, considering the geological characteristics of the middle to high rank coal bearing basins in China, three different middle to high coal rank CBM production fields including the south of Qinshui Basin, the east of Ordos Basin and Lianghuai coal mines were chosen as the study fields. Combining the analysis of geological factors statistics, and the experimental and production data, the results indicate that the coupling of gas content and permeability of coal reservoir determine the formation of enrichment and high production area. Three formation models of CBM enrichment and high production area were proposed. Geological evaluation indicator including seven geological parameters of CBM enrichment and high production area were established by analytic hierarchy process and principal component analysis. CBM production capacity based evaluation method for CBM enrichment and high production area was developed. The above understandings will play an important guiding role in optimizing beneficial CBM exploration target.