Influence Of Basalt From Shahejie Formation In Dongying Depression On The Development And Hydrocarbon Generation Of Source Rocks

A large number of research results indicate that igneous rocks have an important impact on the development and hydrocarbon generation of source rocks.Igneous rocks are widely developed in Dongying Depression.,and a large amount of basalt is distributed in the source rocks of Shahejie Formation,which has an important impact on the development and hydrocarbon generation of source rocks.The paper takes the basalt of the Shahejie Formation as research object,and discusses the impact of basalt on the development and hydrocarbon-generation of the source rocks in the Shahejie Formation on the basis of clarifying the development characteristics and environment of the basalt through core（cuttings）,logging data,thin section and scanning electron microscope observation,major and trace element testing,organic geochemistry experiments,and hydrocarbon generation simulation experiments.The basalt of Shahejie Formation in Dongying Depression is mainly distributed in Binnan area and Gaoqing-Jinjiazhuang area on the plane,and is distributed in the first to fourth members of Shahejie Formation,characterized by multiple eruptions.Basalts in Binnan area developed in underwater preservation environment of underwater spout,and basalts in Gaoqing area developed in underwater preservation environment of onshore eruption.The basalt is mainly alkaline sequence,enriched Pb elements in trace elements,seriously depleted K and P elements,enriched light rare earth elements and depleted heavy rare earth elements in rare earth elements.During volcanic eruption,deep fluids upwelled into sedimentary strata with large amounts of nutrients,resulting in biogenesis and conducive to the enrichment of organic matter.Reducing gases such as H₂S and CO can cut off the air,making water maintain a reducing environment.It is conducive to the preservation of organic matter and laying a foundation for the formation of high-quality source rock.Basalt contains a large number of plagioclase,olivine and other rock-forming minerals and transitional metal elements.Mineral alteration produces a large amount of H₂,and hydrocarbon generation is a process of H consumption,so basalt plays a hydrogenation role for hydrocarbon generation of nearby source rocks.As catalyst,transitional metal elements are activated in the basalt and migrate to the source rock,which plays a catalytic role in generating hydrocarbon from the source rock.Low temperature gas-hydrothermal alteration often occurs in basalt under the condition of abundant CO₂,forming carbonates such as calcite,which can also catalyze the generation of hydrocarbons.