赵官煤田煤层气赋存特征及其控制因素研究
Study on occurrence characteristics and controlling factors of coalbed methane in Zhaoguan Coalfield
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摘要: 基于岩浆活动对煤层气赋存的影响,为得出丰富岩浆活动对煤层气富集作用机理的控制规律,在对赵官煤田煤层气资料、构造条件、煤层灰分、顶底板岩性、煤层埋深、水文地质条件和岩浆活动分析之上,对赵官煤田煤层气赋存特征及其控制因素进行了研究。结果表明:上组煤(7煤、10煤)煤层气含量、含气饱和度明显大于下组煤(11煤、13煤);煤层气赋存影响不明显;煤层灰分与煤层含气量呈负相关;上组煤顶底板岩性致密,完整性好,利于煤层气保存,下组煤顶板受岩浆岩侵入,完整性相对较差,利于煤层气逸散;煤层含气量与煤层埋藏深度正相关,上、下组煤含气量梯度分别为3.67、0.53 m~3/(t·hm);地下水滞水区矿化度高,利于煤层气的保存;岩浆岩附近煤层中煤层气逸散严重,是导致上下煤层含气量相差较大的根本原因。Abstract: Based on coal bed methane(CBM)information,tectonic condition,coal ash,lithology of the roof and floor,seam depth,hydrogeological condition and magmatic activity,this paper had a study on occurrence characteristics and controlling factors of CBM in Zhaoguan Coalfield.The results showed that the CBM content and gas saturation of upper group coal seams (No.7 and No.9)were obviously larger than that of lower group coal seams (No.11 and No.13).The geological structure of this area had no obvious influence on the occurrence of CBM.The ash content of coal seam was negatively correlated with CBM content.The top and bottom plates of the upper group coal seams had dense lithology and good integrity,which was beneficial to preservation of CBM.The roof of lower group coal seams was intruded by magmatic rock and had relatively poor integrity,which was propitious to emission of CBM.The CBM content was positively related to the buried depth of coal seam.The CBM content of upper and lower group coal seam respectively increased 3.67 m3/t and 0.53 m3/t by each hundred meters.Stagnant groundwater area had high salinity groundwater,that was favorable for the preservation of CBM.CBM in coal seam near magmatite diffused seriously.It was the basic reason of the lager difference of CBM content between the upper and lower coal seams.