内蒙古黑城子矿区煤层气资源条件分析

CBM resource condition in Heichengzi coalfield,Inner Mongolia

为了评价内蒙古自治区黑城子矿区煤层气成藏条件、初步估算其煤层气资源潜力、给该矿区煤层气资源勘探开发部署提供地质依据,以黑城子矿区主力煤层为研究对象,分析了矿区煤层空间发育、煤岩类型、灰分、煤变质程度、顶底板岩性分布和水文地质条件等特征。研究结果表明:①黑城子矿区含煤性好,5煤组和6煤组煤层厚度大、分布稳定,煤岩类型以半亮煤为主,腐殖组含量高,灰分较低,为煤层气成藏提供了良好的生气基础;②主力煤层顶板岩性以泥岩、粉砂岩为主,厚度一般大于10 m,有很强的封盖性能,并且具备水力封堵条件,有利于煤层气的保存;③矿区西部煤层埋深500~1000 m的区域为煤层气有利区,通过类比霍林河煤田的煤层气基础地质条件,估算其潜在煤层气资源量为8.0×10^(8)m^(3),资源丰度约为1.82×10^(8)m^(3)/km^(2)。结论认为:①黑城子矿区煤层气资源条件良好,具备进一步勘探开发工作的前景;②下一步应优先在矿区西部进行工作部署,以获取实测含气量、煤储层吸附性、煤体结构、储层压力、压力系数、渗透性等参数。

In order to evaluate the accumulation condition of coalbed methane(CBM)in Heichengzi coalfield,Inner Mongolia,estimate CBM resource potential,and provide geological basis for exploration and development,the main coal beds in this field were analyzed in terms of spatial development characteristics,coal petrology and quality,degree of coal metamorphism,lithologic distribution of roof and floor,and hydrogeologic condition.Results show that(1)in Heichengzi coalfield with better coal-bearing property,both No.5 and No.6 coal beds are featured by large thickness and stable distribution.Semibright coal,as the dominant coal type with rich huminite and poor ash,may provide favorable gas-generating base for CBM accumulation;(2)dominated by mudstone and siltstone,the roof and floor of the main coal bed(most thickness more than 10 m)have strong sealing capacity with hydraulic sealing condition,which is conducive to CBM preservation;(3)some coal beds at the burial depth of 500-1000 m in the western field are favorable targets,and by comparing with the basic geological conditions in Huolinhe coalfield,its CBM resource volume and abundance are estimated to be 8.0×10^(8)m^(3) and 1.82×10^(8)m^(3)/km^(2),respectively.In conclusion,Heichengzi coalfield is good in CBM resource condition and has an exploration and development prospect.What's more,the next step shall be arranged preferentially in the western field so as to obtain such parameters as gas content,reservoir adsorbability,coal texture,reservoir pressure,pressure coefficient,and permeability.