玛湖凹陷风云1井陆相深层页岩气勘探突破及其油气地质意义

Exploration breakthrough and geological significance of continental deep shale gas in Well Fengyun 1 in Mahu Sag

二叠系风城组是玛湖凹陷主力烃源岩和勘探层系,落实深层—超深层页岩油气潜力对玛湖凹陷勘探具有重要指导意义。基于风云1井风城组页岩气发现及前风城组油气勘探成果,系统分析该井的岩性发育特征、烃源岩成烃条件和储层条件,明确玛湖凹陷风城组页岩油气系统中页岩油、气分布序列特征及油气地质意义。研究表明,风云1井风城组岩性主要为盐岩、页岩与粉—细砂岩等;风城组烃源岩有机质丰度总体较低,其中风一段烃源岩最为发育,平均有机碳含量达1.06%;储层整体致密,孔隙度平均为4.65%,其中云质页岩和灰质砂岩储集性能较好。此外,随深度增大玛湖凹陷风城组具有完整的由页岩油、页岩油气到页岩气的演化规律。前风城组油气来源于超深层的另一油气系统,应是下一步勘探的重要领域之一。

The Permian Fengcheng Formation is the main source rock and exploration target in Mahu Sag,and the identification of shale oil and gas potential in deep formations has important guiding significance for further exploration activities.Based on shale gas discoveries in Fengcheng Formation in Well Fengyun 1 and exploration achievements in the underlying pre-Fengcheng Formation,the lithologic characteristics,hydrocarbon generation conditions of source rock,and reservoir conditions in Well Fengyun 1 have systematically been analyzed,and the distribution sequence of shale oil and gas in Fengcheng Formation in Mahu Sag has been determined,showing great geological significance.The study results show that Fengcheng Formation in Well Fengyun 1 is mainly composed of salt rock,shale,and silty-fine sandstone;Fengcheng Formation source rock has a relatively low organic matter abundance,and that in the first member has the best quality,with an average TOC of 1.06%;The reservoir is generally tight with an average porosity of 4.65%,and the dolomitic shale and limy sandstone have relatively better physical properties.With the increasing depth,a complete hydrocarbon distribution pattern from shale oil,to shale oil and gas,and to shale gas occurs in Fengcheng Formation in Mahu Sag.In addition,pre-Fengcheng Formation shows good resource potential with hydrocarbon source supplied by the ultra-deep oil and gas system,which is a major field for further exploration.