The Basament Lithology Magnetic Seismic Joint Interpret Of Ancient Central Uplift Belt Of Songliao Basin

The deep-seated gas exploration has made a breakthrough in volcanic gas reservoir and dense Glutenite reservoir.Then the expansion of the natural gas exploration and scale necessitates a further exploration on new strata and new fields.The paleo-central uplift belt of Songliao basin has become one of the key areas where to explore new fields at present since it has been found with natural gas though has not formed industrial scale yet.Based on the materials about field outcrops around the west,east and south of the basin,this article sets up the basement strata as well as the stratigraphic sequence,and also establishes the types of basement rocks.The basement of Songliao basin mainly consists of carboniferous-permian.Rocks developed in the base is composed of tuff,andesite,granite,mudstone,sandstone,conglomerate,schist,slate,phyllite,mylonite,fractured porphyry,etc.By testing abundant geophysical parameters of field rock samples and drilling core samples,the article exposes geophysical characteristics of various types of rock in the basement,and classifies four rock associations,which are mylonite and phyllite of high density,andesite,granite and diorite of medium density,fractured granites of low density and low magnetism,along with glutenite,slate and schist of low density respectively.A lithological gravitational magnetic simultaneous inversion has been conducted,under the help of the deep viewing density and visual magnetic ratio maps of 3500-4000 m,4000-4500 m and 4500-5000 m underground,and then the corresponding lithology prognostic maps have been drawn.The final analysis concludes the lithologic distribution characteristics of the basement.The sedimentary rock coverage area is relatively larger 3500-4000 m underground,and the basement grows continuously throughout the north and the south.The basement lithologics mainly includes the combination of andesite,granite and diorite which assemble in central and southern regions.Besides,in the areas of 4000-4500 m,4500-5000 m below ground,the group of sandstone,conglomerate,slate and schist is wildly developed,followed by the group of Mylonite and phyllite which develops together with the group of granite,andesite and diorite.The development area of fractured granites is the smallest.Such granites only scatters throughout parts of the region.The research results will provide a scientific basis for a further oil-gas exploration and the selection of beneficial exploration target areas.