渤海南部明化镇组下段源?汇体系及其对大面积岩性油气藏的控制作用

近年来，在渤海南部新近系钻遇了大量大面积砂体，并发现了多个亿吨级油田，表明明化镇组下段勘探潜力巨大。该类砂体发育形成源?汇要素不清，严重制约了明下段的岩性油气藏勘探。文章利用古生物、重矿物、地震、钻井等资料，探讨了渤海南部浅层明下段源?汇体系及其对大面积岩性油气藏的控制。结果表明:渤海南部明下段沉积期发育多个方向的源?汇体系，其中，燕山?辽西隆起方向距离研究区最远，辽东隆起次之，鲁西隆起和胶东隆起较近，鲁西隆起和辽东隆起对研究区源?汇系统影响较大，燕山?辽西隆起对源?汇系统影响较弱；研究区明下段沉积期主要发育河流、河湖交互和湖泊这三种沉积体系，其中，河湖交互和湖泊浅水三角洲形成的砂体面积较大；研究区明下段沉积期具备形成大面积砂体的有利源?汇条件，其中，温带?亚热带气候、充足的降雨量、发达的古水系、长英质变质岩和岩浆岩母岩、湖泊范围频繁的扩大和缩小有利于大面积砂体的发育；河道砂?席状砂?河道砂的连通导致研究区明下段发育大面积的岩性圈闭，与单独的河道砂相比，河湖交互和浅水三角洲具有形成大面积岩性油气藏的潜力。该认识可为渤海海域新近系大型油气藏的勘探提供帮助。 

The source-sink system and its control on large-area lithologic reservoirs of the lower Minghuazhen Formation in the southern Bohai Sea

In recent years, a large number of large-area sand bodies have been drilled in the Neogene in the southern Bohai Sea, and several 100-million-ton oilfields have been discovered, indicating that the lower member of the Minghuazhen Formation has enormous exploration potential. The source-sink elements of the development of such sand bodies are unclear, which seriously restricts the exploration of lithologic reservoirs in the lower member of the Minghuazhen Formation. Using paleontology, heavy minerals, seismic, drilling and other data, this paper explores the source-sink system and its control on large-area lithologic reservoirs in the lower member of the Minghuazhen Formation of the southern Bohai Sea. The results show that: The Yanshan-Liaoxi uplift, the Liaodong uplift, the Luxi uplift and the Jiaodong uplift mainly develop source-sink systems in four directions in the study area’s lower member of the Minghuazhen Formation. Next, the Luxi uplift and the Jiaodong uplift are relatively close. The Luxi uplift and the Liaodong uplift significantly impact the source-sink system in the study area’s lower part of the Minghuazhen Formation. In contrast, the Yanshan-Liaoxi uplift has a weaker impact on the source-sink system. Three sedimentary systems, including rivers, river-lake interactions and lakes, are mainly developed in the study area’s lower member of the Minghuazhen Formation. Among them, the sand bodies formed by river-lake interactions and lake shallow water deltas are larger. The study area’s lower member of the Minghuazhen Formation has favorable source-sink conditions for creating large-scale sand bodies. Among them, temperate-subtropical climate, sufficient rainfall, developed paleo-water system, felsic metamorphic rocks and magmatic parent rocks, and frequent expansion and shrinkage of lakes are beneficial to the development of large-area sand bodies. The connection of channel sand–sheet sand–channel sand leads to the development of large-scale lithologic traps in the study area’s lower member of the Minghuazhen Formation. Compared with channel sand alone, river-lake interactions and shallow water deltas have the potential to form large-area lithologic reservoirs. This understanding can help explore large Neogene oil and gas reservoirs in the Bohai Sea.