内蒙古黑山煤田煤层气资源潜力评价

Evaluation on resource potential of CBM, Heishan coalfield, Inner Mongolia

为了推进内蒙古黑山煤田煤层气资源勘查开发工作、尽快取得煤层气资源勘查突破,以该煤田主力煤层为研究对象,分析了黑山煤田煤层气的基础地质条件,主要包括煤层厚度和埋藏深度、煤岩煤质特征、煤储层物性特征及保存条件等;进而根据煤层气勘查规范及前人的研究成果,制定了黑山煤田煤层气资源选区评价标准。研究结果表明:①黑山煤田主力煤层厚度大,分布广,煤变质程度合适,宏观煤岩类型以光亮—半亮型为主,镜质组含量高,有良好的生烃潜力;②整体处于相对滞留的水动力环境中,煤层顶底板岩性以泥岩、粉砂岩为主,厚度大,封盖能力强,有利于煤层气的富集和保存;③煤层埋深一般在600~1 000 m,并且孔隙性较好,裂隙系统较发育,有利于煤层气的经济开发;④依据评价标准确定了黑山煤田煤层气资源远景区、有利区、目标区位置和范围,预测煤层气资源量约810×10~8m^3,资源丰度约0.98×108m^3/km^2。建议在优选目标区内部署参数井,以进一步获得实测含气量、储层压力、压力梯度、含气饱和度、煤储层渗透性等关键参数。

In order to make a demonstrative exploration breakthrough of coalbed methane (CBM) resources in coal-bearing basins, western Inner Mongolia, this paper took the principal coal bed of Heishan coalfield as an example to analyze its basic geologic conditions. Then, some standards to select and evaluate CBM resource areas in this field were formulated based on exploration norms. Results show that (1) the principal coal bed is thick and extensive. Its coal metamorphic degree is moderate, rock types are mainly bright coal and semi-bright coal, and vitrinite content is high, all presenting strong hydrocarbon-generating potential;(2) on the whole, it's in a hydrodynamic environment which is relatively detained. Both top and bottom coal bed is mainly composed of thick mudstone and siltstone with strong sealing capacity available for CBM accumulation and preservation;(3) the coal bed is generally 600~1000 m deep with better porosity and developed fracture systems, which is favorable for a cost-effective development;and (4) the position and range of plays and the favor able targets of CBM resources in Heishan coalfield are defined according to these evaluation standards. The predicted CBM resources and abundance are 810×108 m3 and 0.98×108 m3/km2, individually. In conclusion, the key parameters of gas content, reservoir pressure, pressure gradient, gas saturation, and permeability can be measured further by deploying param eter wells in the selected target areas.