Interpretation Of Gravity And Magnetic Anomalies In The Bohai Sea And The North Yellow Sea

Bohai is the shallowest semi-closed inner sea in China,Located in the northern-most part of eastern China,Covering the northeast of Bohai Bay Basin.The oil and gas exploration results and potential is huge.It is an important succession battlefield for oil and gas exploration in the eastern China.The North Yellow Sea is located between the Shandong Peninsula,the Liaodong Peninsula,and the Korean Peninsula,it is also the semi-closed sea,The North Yellow Sea Basin develops in it,The structure of the area is complex,it is an unexploited oil and gas prospect.Bohai Bay Basin and the North Yellow Sea Basin both are Cenozoic fault basin.The occurrence of tectonic movement evolution changes the lithology,basin properties,structural features such as faults,etc.Using the high-anomaly,aeromagnetic anomaly,aeromagnetic anomaly data and obtained topographic and sedimentary data from the study area.Analyze the geological and geophysical data of the study area and establish a brief geological stratigraphic model for the distribution of the subsurface density distribution.Applying the variable density interface forward and inversion methods to qualitative and quantitati-ve constraints,based on seismic,logging,geological and other data,We separat bouguer gravity anomalies to obtain regional anomalies and residual anomalies,based on the theory of “separating layer by layer”,Combined with the regularization filtering equipotential field separation method.And then use the regional anomaly to get the depth of Moho in the area using inversion.By the method of border identification,such as processing of various derivatives,extensions,etc.Conbine with the magnetic anomaly data of the measurement area,perform magnetization pole and separation,and analyze the signal and so on.We get the study area boundary and structural fault and the distribution of rock mass in the area.Coming the inferred fracture interpretation and the existing formation thickness and density information in the survey area,the inversion of sediment thickness in the survey area is carried out.Based on this,Performing 2.5D gravity inversion of major oil and gas potential areas,Then performing comprehensive interpretation combined with inferred fracture characteristics.Based on the analysis and study of the basic theory and application of constraint forward and interface inversion with variable density model,it is further proved that the constraint forward and interface inversion with variable density model can provide more accurate and reliable method reference for research in other exploration areas in sedimentary interface inversion and deep structural research.The paper is based on the above theory,Combining previous research results,Analyzing the rock properties and stratigraphic characteristics and tectonic movements,magmatic activities in the study area and its surroundings,Performing explanation to the results of gravity and magnetic anomaly processing.And making redivision to the boundary of the extension of the Bohai Bay Basin in the Bohai Sea,And the boundary adjustment of the Bozhong depression and the extension of the Huanghua depression and the Lower Liaohe depression,and the Jiyang depression.The analysis of re-staged concave and bulge structure,such as Bozhong sag and Shijiutuo bulge,Further inferred the division of secondary structural units in the North Yellow Sea Basin of the boundary.Combined with the results of the sea-earth seismic survey in the Bohai Sea,performing inversion study to obtain Moho depth,Joint inversion of profiles to further study the distribution characteristics of sedimentary layers in the survey area.Advance the development of the research on the combination of mantle and crust in the area and the macroscopic distribution of the inner stratum,analyzing the magnetic anomalies and their processing results,Adjusting the Tantalum fault zone and Zhangjiakou Penglai Fault in Bohai Sea and North Yellow Sea Fault System,Newly delineated the distribution of rock masses,Enrich the underStanding of geological structure in the area.