淮南煤田连塘李井田煤层气地质特征

CBM Geological Features in Liantangli Minefield,Huainan Coalfield

为了查明连塘李井田煤层气赋存及开发地质条件,在井田内实施了两口煤层气探井,并开展了系统的分析测试工作。结果表明:连塘李井田主要煤层压汞孔隙比表面积平均为3.43m 2/g,压汞总孔容平均为0.11ml/g,煤层试井渗透率分布在0.05~0.08mD,孔隙系统发育一般,渗透性较差;主要煤层兰氏压力(空气干燥基)平均为3.12MPa,兰氏体积(空气干燥基)平均为6.84m 3/t,吸附能力较低;两口井气测录井异常次数较多,16-12井共发现16次异常显示,23-3井共发现41次异常显示,两口井全烃含量最大值分别为8.21%和8.23%,气测录井解释煤层含气性一般;主要煤层的实测含气量平均1.09m 3/t,含气饱和度最大为20.84%,具有低含气量和低饱和度的特征。综合分析认为,连塘李井田位于阜凤逆冲推覆构造前锋部位,构造复杂,煤层渗透率低,含气量及含气饱和度低,煤层气地面开发难度大,具有较高的勘探风险。

To find out CBM hosting and exploitation geological condition in the Liantangli minefield,two CBM exploration wells have been drilled and systematic analysis and testing works implemented.The results have shown that the minefield main coal seams mean pore specific surface area is 3.43m 2/g,mean total pore volume 0.11ml/g from mercury intrusion porosimetry,testing well coal seam permeability between 0.05~0.08mD,pore system development is fairly general with poorer perviousness.Main coal seams Langmuir pressure(air dried basis)average is 3.12MPa,Langmuir volume(air dried basis)average 6.84m 3/t,with rather low adsorptivity.Gas logging has found more anomalies in two wells,in well 16-12 has 16 anomalies,in well 23-3 has 41 anomalies,maximum total hydrocarbon content of the two wells is 8.21%and 8.23%respectively.Thus,coal seam gas-bearing property from gas logging is fairly general.Main coal seams measured average gas content is 1.09m 3/t,maximum gas saturation 20.84%,thus has low gas content and saturation features.Comprehensive analysis has considered that the minefield is situated on the front of Fufeng thrust nappe structure with complicated structures;coal seams have low permeability,gas content and gas saturation low.Thus,CBM surface exploitation is rather difficult with higher exploration risks.