桂中坳陷下石炭统鹿寨组页岩气成藏条件和有利区预测

以桂中坳陷野外考察和岩心观察为基础，结合地球化学、扫描电镜、全岩X射线衍射和低温气体吸附等数据，分析了下石炭统鹿寨组的泥页岩分布、有机地球化学参数、储层特征和含气性等页岩气成藏的地质条件。研究表明，桂中坳陷下石炭统鹿寨组页岩以深水陆棚相沉积为主，富有机质页岩的分布面积广，沉积厚度一般在50~300 m，埋深适中；页岩的有机碳含量大于1.5%，有机质成熟度达到高成熟-过成熟阶段；储层中脆性矿物较多，孔隙空间发育较好，气体吸附性能好，具备页岩气聚集成藏的有利地质条件。结合桂中坳陷剥蚀厚度较大、经历断裂和岩浆活动较多、页岩气保存环境较差等问题综合分析，认为柳州-鹿寨和河池-宜州地区一带为桂中坳陷下石炭统鹿寨组页岩气勘探的有利区。

Shale gas accumulation conditions and prediction of favorable areas for the Lower Carboniferous Luzhai Formation in Guizhong depression

Based on field investigation and cores observation,in combination with the data of geochemistry,scanning electron microscopy,X-ray diffraction and low-temperature gas adsorption,this study analyzes the geological conditions of shale gas accumulation such as mud shale distribution,geochemical parameters,reservoir characteristics and gas-bearing characteristics in the Lower Carboniferous Luzhai Formation in Guizhong depression. The study shows that the shale from the Lower Carboniferous Luzhai Formation in Guizhong depression is dominated by deep-water continental shelf sediments. The organic-rich shale is distributed widely,generally with the sedimentary thickness from 50m to 300m and moderate buried depth. The organic carbon content in shale is above 1.5%,and the organic matter reaches the high mature or over mature stage. That brittle minerals,pore spaces and gas adsorption performances are well developed in the reservoir indicate favorable geological conditions for shale gas accumulation. In combination with the comprehensive information that Guizhong depression has large erosion thickness,experiencing multi-stage faults and magmatism and poor shale gas preservation environment,it is believed that the Liuzhou-Luzhai area and the Hechi-Yizhou area are favorable areas for shale gas exploration in the Lower Carboniferous Luzhai Formation,Guizhong depression.