羌塘盆地温泉地区天然气水合物地球化学异常及其成藏地质条件分析

The Geochemical Anomaly of Gas Hydrate in Wenquan Region of Qiangtang Basin and Its Implications of Accumulated Geological Conditions

温泉地区冷泉气中CH4的平均含量较高,具有极高的地球化学异常,同时发现有天然气水合物渗漏的证据——冷泉碳酸盐的存在。研究表明:研究区布曲组(J2b)泥岩及碳酸盐岩为好的烃源岩,有机质丰度高、类型好、成熟度高,具有较好的生烃潜力,为优质的供烃层;J2b中的鲕粒灰岩、生屑灰岩以及J2b和夏里组中的砂岩,孔隙及裂缝发育,是良好的储集层;卷入侏罗系的温泉背斜,J2b上部的泥岩、钙质泥岩、泥晶灰岩等致密岩性层以及温泉地区多年冻土带等,形成了研究区良好的圈闭和盖层;研究区具备天然气水合物聚集成藏的基本地质要素和良好的勘探前景。

The geochemical anomaly of gas hydrate was found in Wenquan Region.The average content of CH4 was high in cold spring gas,it had very high geochemical anomaly.As evidence of gas hydrate leakage,cold seep carbonate was found in Wenquan Region.Studies showed that as good hydrocarbon source rock,the mudstone and carbonate rocks in Buqu Formation were rich in organic matter with favorable organic matter type and high thermal maturity,there existed better hydrocarbon generation potential with good hydrocarbon source.The pores and fractures were developed in oolitic limestone,bioclastic limestone in Buqu Formation and sandstone in Xiali Formation,they were good reservoirs.Wenquan anticline,the regionally distributed mudstone,calcareous mudstone,micrite and permafrost in Wenquan,formed a good trap and cap in the study area.The study area has good basic geological factors for accumulation of gas hydrate,which is considered as a potential exploration target after integrated geological evaluation.