Formation Conditions and Geological Significance of Large Archean Buried Hill Reservoirs in Bohai Sea

In recent years, many large oil and gas fields of the Archaean buried hills in the Bohai Sea have been discovered, among which, the natural gas reserves of Bozhong 19-6 structure exceed 100 billion cubic meters, showing the huge exploration potential in this field. The scale of buried hill reservoirs is the key factor restricting the exploration of metamorphic rock. It is of great theoretical and practical significance to study the formation conditions of large-scale buried hill reservoirs. Based on the experimental data of cores, thin sections, scanning electron microscopy and seismic data, in this paper it systematically analyzes the formation conditions of several large metamorphic buried hill reservoirs in the Bohai Sea area. The results show follows: (1) The brittle felsic minerals are the important material basis for the development of large buried hill reservoirs of Archean metamorphic rocks in Bohai Sea area, which are not only conducive to the development of fractures, but also provide favorable conditions for weathering leaching and dissolution of deep fluids. (2) The multiple types of compressive structures control the formation of large fractured reservoirs. (3) Weathering and leaching is an important factor in the vertical zonation of Archean buried hill reservoir, which obviously controls the vertical development of Archean buried hill reservoirs. (4) The deep fluid plays an important role in improving the Archean buried hill reservoirs, expanding the scale of fractures. Under the guidance of the above formation conditions, the genetic model of Archean large buried hill reservoirs is established.